Chiari-like Malformation (CM) and Syringomyelia (SM)  in the
Cavalier King Charles Spaniel

Page 3 – Veterinary Resources

Veterinary Resources

This is a list of citations and summaries of veterinary research journal articles which are applicable to Chiari-like malformation (CM) and syringomyelia (SM) and cavalier King Charles spaniels.

This list is in chronological order, from 1974 to the present, with the most recent additions added at the bottom of this page. Hyper-linked titles are linked to the actual articles which are available on-line. 

1974 - 2002

The hitch-hiking effect of a favourable gene. John Maynard Smith, John Haigh. Genetics Res. February 1974; doi: 10.1017/S0016672300014634. Quote: When a selectively favourable gene substitution occurs in a population, changes in gene frequencies will occur at closely linked loci. In the case of a neutral polymorphism, average heterozygosity will be reduced to an extent which varies with distance from the substituted locus. The aggre- gate eifect of substitution on neutral polymorphism is estimated; in populations of total size 106 or more (and perhaps of 104 or more), this eifect will be more important than that of random fixation. This may explain why the extent of polymorphism in natural populations does not vary as much as one would expect from a consideration of the equilibrium between mutation and random fixation in populations of different sizes. For a selectively maintained polymorphism at a linked locus, this process will only be important in the long run if it leads to complete fixation. If the selective coefficients at the linked locus are small compared to those at the substituted locus, it is shown that the probability of complete fixation at the linked locus is approximately exp (— Nc), where c is the recombinant fraction and N the population size. It follows that in a large population a selective substitution can occur in a cistron without eliminating a selectively maintained polymorphism in the same cistron.

Mechanism of the decrease in intracranial pressure as affected by furosemide. Pinegin LE, Dolzhenko DA, Natochin IuV. Biull Eksp Biol Med 1984;98:682–685.

Furosemide lowers intracranial pressure by inhibiting CSF production. Lorenzo AV, Hornig G, Zavala LM, et al. Z Kinderchir 1986;41(Suppl 1):10–12.

Dorsal notch of foramen magnum due to incomplete ossification of supraoccipital bone in dogs. Watson, A.G., De Lahunta, A., and Evans, H.E. J. Small Anim. Prac. 1989 30:666-673.

Effect of histamine H2 receptor antagonists on the secretion of cerebrospinal fluid in the cat. Naveh Y, Kitzes R, Lemberger A, Ben-David S, Feinsod M. J Neurochem. 1992 Apr;58(4):1347-52.

Occipital dysplasia and associated cranial spinal cord abnormalities in two dogs. Rodney S. Bagley, Michael L. Harrington, Russell L. Tucker, Ronald D. Sande, Charles R. Root, Robert W. Kramer. Vet. Rad. & Ultra. Sept 1996; 37(5): 359. Quote: "Occipital dysplasia was found in association with cervical spinal cord abnormalities in two dogs. One dog presented for tetraparesis and cervical hyperesthesia, the other [a Yorkshire terrier] for historical cervical hyperesthesia and mild paraparesis. In dog 1, a midline cervical spinal cord defect consistent with a communicating syrinx was found. In the other dog, a presumptive syringo/hydromyelia of the cervical spinal cord was found on magnetic resonance imaging. While occipital dysplasia alone is not thought to cause any clinical abnormalities, the dogs of this report suggest that intramedullary central nervous system abnormalities may be present concurrently with occipital dysplasia and should be considered as a possible cause of the clinical signs. The relationship between occipital dysplasia and syringo/hydromyelia in these dogs remains unclear, however, similar associated abnormalities are occasionally found in humans with Chiari malformation."

Hydromyelia in the dog. Robert M. Kirberger, Linda S. Jacobson, Jeremy V. Davies, Jean Engela. Vet. Radiology & Ultrasound. January 1997;38(1):30-38. Quote: "Hydromyelia is a dilation of the spinal cord central canal. In man this may be due to congenital malformations such as Dandy-Walker syndrome and Chiari malformations or may be acquired as result of infection, trauma or neoplasia. In dogs hydromyelia may be accidentally diagnosed during routine cisterna magna myelography. Hydromyelia, and its possible etiology, may be confirmed by means of computed tomography or magnetic resonance imaging. Three dogs with hydromyelia {two Maltese poodles and one King Charles spaniel] due to differing etiologies are described."

Persistent scratching in Cavalier King Charles spaniels.  Rusbridge C. Vet Rec. Aug 1997;141(7):179.

Different effects of omeprazole and Sch 28080 on canine cerebrospinal fluid production. Javaheri S., Corbett W. S., Simbartl L. A., Mehta S., Khosla A. Brain Research 1997; 754(1-2); 321-324. Quote: "We investigated the effects of omeprazole and Sch 28080, a more specific and a more potent inhibitor of K+,H+-ATPase than omeprazole, in canine cerebrospinal fluid (CSF) production. ... [T]he percent decreases in CSF production in the omeprazole treated group were ... significantly more than the respective values in the control group. ... We conclude that in the canine model, physiological doses of omeprazole decrease CSF production by about 26. However, the effect is independent of the K+,H+-ATPase activity, since Sch 28080 which is more potent than omeprazole did not significantly affect CSF production."

A syndrome of syringomyelia in the cavalier King Charles spaniel, and its treatment by syringo-subarachnoid shunting. Skerritt GC, Hughes D:  In Proceedings from the 12th Annual Symposium of the European Society of Veterinary Neurology, Vienna, 23: 1998.

Syringohydromyelia in Cavalier King Charles spaniels.  Rusbridge C, MacSweeny JE, Davies JV, Chandler K, Fitzmaurice SN, Dennis R, Cappello R, Wheeler SJ. J Am Anim Hosp Assoc. 2000 Jan-Feb;36(1):34-41.

Chiari 1/syringomyelia complex in a King Charles Spaniel.  Churcher RK, Child G. Aust Vet J. 2000 Feb;78(2):92-5. Quote: "A 9-year-old King Charles Spaniel presented with a history of progressive forelimb weakness and paroxysmal involuntary flank scratching over a 2-year period. Neurological examination suggested a myelopathy of C1 to C4 spinal cord segments. Advanced imaging studies revealed hydrocephalus, caudal herniation of part of the caudal lobe of the cerebellum through the foramen magnum and marked syrinx formation to the level of the caudal thoracic spine, resembling Arnold-Chiari malformation with secondary hydromyelia in humans. Mechanical obstruction at the craniocervical junction, altering CSF flow dynamics, may lead to syrinx formation. Response to diuretic therapy was moderate but surgical decompression may offer better long term prognosis."

Dorsal dens angulation and a Chiari type malformation in a Cavalier King Charles Spaniel.  Bynevelt M, Rusbridge C, Britton J. Vet Radiol Ultrasound. 2000 Nov-Dec;41(6):521-4.

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2003

Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases.  Stern-Bertholtz W.; Sjöström L.; Wallin Håkanson N.  J Small Anim. Prac., June 2003, 44(6): 253-256(4).

Hereditary aspects of occipital bone hypoplasia and syringomyelia (Chiari type I malformation) in cavalier King Charles spaniels.  Rusbridge C, Knowler SP. Vet Rec. Jul 2003;153(4):107-12.

Neurological signs and results of magnetic resonance imaging in 40 cavalier King Charles spaniels with Chiari type 1-like malformations.  Lu D, Lamb CR, Pfeiffer DU, Targett MP. Vet Rec. Aug 2003;153(9):260-3. Quote: In human beings a Chiari type 1 malformation is a developmental condition characterised by cerebellar herniation and syringohydromyelia. Abnormalities compatible with such a malformation were identified by magnetic resonance imaging in 39 cavalier King Charles spaniels with neurological signs and in one neurologically normal cavalier King Charles spaniel that was examined postmortem. The dogs with these abnormalities had a wide variety of neurological signs, but there was no apparent correlation between the neurological signs and the severity of cerebellar herniation, syringohydromyelia or hydrocephalus.

Suboccipital Craniectomy and Cranial Dorsal Laminectomy as a Treatment Option for Chiari Type I Malformation Malformation In the Cavalier King Charles Spaniel. K. Vermeersch; L. Van Ham; J. Caemaert; M. Tshamala; O. Taeymans; S. Bhatti; I. Polis1. ESVN 2003 Symposium Abstract 14, J.Vet.Int.Med. 19(2). Quote: "Syringohydromyelia combined with cerebellar tonsil herniation, known as Chiari type I malformation (CIM) is known to occur in Cavalier King Charles spaniels in many countries. The dogs either have progressive cranial (eg, facial deficits, seizures, vestibular syndrome) or spinal (eg, hyperesthesia with persistent scratching of shoulder and neck region) symptoms. Diagnosis is best made by magnetic resonance imaging (MRI): fluid-filled cavity within the spinal cord and cerebellar tonsil herniation. As therapeutic options medical treatment with corticosteroids, acetazolamide, NSAIDs or oral opioids may give an improvement but most often not a resolution of signs. It is thought that syrinx formation in humans and dogs with CIM occurs secondary to partial obstruction of CSF flow at the cranio-cervical junction. Therefore, in human medicine, a suboccipital craniectomy and cranial dorsal laminectomy with opening of the dura mater is the procedure of choice for surgical treatment of CIM. This surgical technique was performed on 4 Cavalier King Charles spaniels diagnosed with Chiari type I malformation by symptoms (scratching of neck region) and by MRI. The dogs were evaluated neurologically 24 hours, 1 month and 3 months postoperatively. Control MRI took place 3 months postoperatively. Three dogs recovered uneventfully from anesthesia. The fourth dog was euthanized within 24 hours after surgery at owners request due to progressive seizures and decreased capability of oxygen saturation. Neurologically, the 3 dogs did worse 24 hours after surgery (neck pain, neck weakness and head tilt), improved gradually and by 3 months postoperatively, achieved the same neurological state as before surgery. Control MRI of the 3 dogs at that time showed no regression of syrinx size. The results of this study indicate that there is no improvement on short term basis in either syrinx size or clinical symptoms after surgical intervention with a suboccipital craniectomy and cranial dorsal laminectomy with opening of the dura. Seen the progressive nature of the disorder, follow-up over a longer period of time is necessary to see if this surgical technique may influence the progression of syrinx formation and clinical signs in Cavalier King Charles spaniels with Chiari type I malformation."

Sound Wave Therapy Not So Shocking. Kate Chope, José M. García-López. Tufts Vety School,  Dec 2003 Case Report. http://www.tufts.edu/vet/vet_common/pdf/petinfo/dvm/case_dec2003.pdf

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2004

Gabapentin is a first line drug for the treatment of neuropathic pain in spinal cord injury. Levendoglu F, Ogun CO, Ozerbil O, et al. Spine 2004;29:743–751.

Amantadine, an N-methyl-d-aspartate antagonist, for treatment of chronic neuropathic pain in a dog. Madden M, Gurney M, Bright S. Vet. Anaesthesia & Analgesia. March 2014;41:440–1.

Suboccipital craniectomy, dorsal laminectomy of C1, durotomy and dural graft placement as a treatment for syringo-hydromyelia with cerebellar tonsil herniation in Cavalier King Charles spaniels.  Vermeersch K, Van Ham L, Caemaert J, Tshamala M, Taeymans O, Bhatti S, Polis I. Vet Surg. 2004 Jul-Aug;33(4):355-60. Quote: "Objective— To evaluate retrospectively the efficacy of the suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft for treatment of syringohydromyelia (SHM) because of cerebellar tonsil herniation in Cavalier King Charles spaniels (CKCS). This technique is used with great success in human medicine. Study Design— Four CKCS diagnosed by Magnetic resonance imaging (MRI) of SHM because of cerebellar tonsil herniation and not responsive to medical therapy underwent a suboccipital craniectomy and dorsal laminectomy of C1 (2 dogs) and of C1 and partial C2 (2 dogs) with durotomy and placement of a dural graft. Three dogs were evaluated neurologically 24 hours, 1 month, and 3 months postoperatively and evaluations were compared with preoperative neurological examination. Repeat MRI took place 3 months postoperatively. Results— Neurological examinations showed neither improvement nor progression of clinical signs 3 months postoperatively. MRI showed no regression of syrinx size 3 months postoperatively. Conclusion— Improvement was not seen. Given the progressive nature of the disorder, evaluation over a longer period of time is necessary to detect if progression has stopped. Some modification to the surgical technique is needed to accomplish the same results as in human medicine. A study of a larger population is needed to attain more reliable information. Clinical Relevance— Suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft is a feasible technique in CKCS, but needs some modification to accomplish the same results as in human medicine."

Inheritance of occipital bone hypoplasia (Chiari type I malformation) in Cavalier King Charles Spaniels.  Rusbridge C, Knowler SP.  J Vet Intern Med. 2004 Sep-Oct;18(5):673-8.

Caudal occipital malformation syndrome in dogs.  Dewey CW, Berg JM, Stefanacci JD, et al. Compend. Contin. Educ. Pract. Vet. November 2004;26(11):886-896. Quote: "Chiari type 1 malformation in humans is a congenital abnormality of the caudal occipital bone, resulting in overcrowding of the caudal fossa and compression at the level of the cervicomedullary junction. Both direct bony compression and progressive meningeal hypertrophy at the level of the posterior (dorsal) cervicomedullary junction are believed to lead to abnormalities of cerebrospinal fluid flow dynamics. Central nervous system dysfunction often develops in patients with Chiari type 1 malformation, with a variety of possible neurologic manifestations. A disorder similar to human Chiari type 1 malformation occurs in dogs, but characteristic disease features have not been thoroughly described. Most of the literature pertaining to the canine form of the disease is from the United Kingdom, and almost all affected dogs have been cavalier King Charles spaniels. Most reports describe patients with cervical myelopathy due to syringohydromyelia. Forty cavalier King Charles spaniels from the United Kingdom were recently described with Chiari type 1 malformations; these dogs displayed a wide variety of neurologic presentations, including central vestibular dysfunction, seizure activity, and cervical myelopathy. We have reviewed 30 cases of canine Chiari type 1 malformations diagnosed via MRI at our hospitals from 2001 to 2002. This article reviews the pathophysiology, clinical features, available treatment options, and prognosis for canine Chiari type 1 malformations. Aspects of the human disorder and information from previously published canine cases are discussed. However, the focus is on the 30 recently reviewed cases. Results of this study suggest that caudal occipital malformation syndrome is relatively common in small-breed dogs and has many clinical similarities to Chiari type 1 malformation in humans."

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2005

Hindbrain decompression in a dog with scoliosis associated with syringomyelia. Takagi S, Kadosawa T, Ohsaki T, Hoshino Y, Okumura M, Fujinaga T.  JAVMA, 2005 Apr.; 226 (8).

Neurological diseases of the Cavalier King Charles spaniel.  Rusbridge, C. J.  Small Anim. Prac., June 2005, 46(6): 265-272.

Treatment of Caudal Occipital Malformation Syndrome in Dogs by Foramen Magnum Decompression. CW Dewey, JM Berg, G Barone, DJ Marino, JD Stefanacci. J Vet Intern Med; May/June 2005;19(3) (ACVIM 23rd Ann. Vet. Med. Forum Abstract Program: Abstract 71). Quote: "Caudal occipital malformation syndrome (COMS) is the canine analog of human Chiari I malformation. As with human Chiari I malformation, dogs with COMS can display a variety of clinical signs; these include cerebellovestibular dysfunction, myelopathy (usually cervical), and seizure activity. Foramen magnum decompression (FMD) is usually performed for humans with symptomatic Chiari I malformation; results are favorable, with better outcomes being attained with early surgical intervention. The purpose of this study was to describe clinical results of a FMD procedure in 16 dogs with COMS. Cases were restricted to dogs with MRI evidence of COMS and no other neurologic disorders. All dogs underwent a FMD procedure that included either meningeal resection or marsupialization to the surrounding musculature. Fifteen of 16 dogs were receiving medical therapy for COMS prior to surgery. Breeds included Cavalier King Charles spaniel (9), Maltese (2), Yorkshire terrier (1), and Pomeranian (1). Mean age was 3.86 yrs. Neuroanatomic localization included multifocal CNS dysfunction (7), isolated cervical myelopathy (6), isolated cerebellovestibular dysfunction (2), and L4-S1 myelopathy (1). All dogs with multifocal CNS signs had evidence of both cerebellovestibular and cervical spinal cord disease. Other specific abnormalities included cervical hyperesthesia (13), diminished menace responses (7), positional strabismus (7), excessive scratching behavior (6), torticollis (3), abnormal mentation (2), “fly-biting” episodes (2), head tilt (2), chewing at the paws (2), excessive licking (1), eye rubbing (1), and generalized seizures (1). Mean duration of clinical signs prior to surgery was 32.19 wks (1-208 wks). Syringohydromyelia was evident on MRI in 15/16 dogs (93.75%). No intraoperative complications occurred. Postoperative complications occurred in two dogs. One dog had worsening of a head tilt, which resolved in three weeks. Another dog experienced neck pain after the initial FMD (resolved in four wks), and was nonambulatory tetraparetic following repeat FMD. Resolution of clinical signs occurred in seven dogs (43.75%), and improvement occurred in six dogs (37.5%), for an overall positive result of 81.25%. One dog did not improve, one dog worsened and was euthanized, and one dog died nine days following repeat FMD (the tetraparetic dog), due to a suspected ruptured viscus. Repeat surgery was performed in 4 dogs (25%), due to constrictive scar tissue formation at the original FMD site. Drugs were discontinued in all dogs with resolution of signs. Four of the 6 improved dogs remained on medical therapy. Five of 6 dogs with scratching behavior prior to FMD continued to do so postoperatively; two of these five dogs required medical therapy to control scratching. Mean duration of signs prior to FMD was 3.8 wks for the resolved group, and 78.08 wks for the improved group. Results suggest that FMD is often an effective treatment for COMS, especially if performed early in the disease course."

CSF flow abnormalities in caudal occipital malformation syndrome. PA March, CJ Abramson, M Smith, and J Murakami. J Vet Intern Med 2005;19:418 (ACVIM 23rd Annual Veterinary Medical Forum Abstract Program: Abstract 72). Quote: "The pathogenic factors responsible for the progression of signs in the caudal occipital malformation syndrome (COMS) are not well understood. The development of secondary syringohydromyelia appears to coincide with the onset of clinical neurologic deficits but the CSF flow abnormalities that lead to syrinx formation have not been described in dogs with COMS. The purpose of this study was to characterize and compare CSF flow dynamics in normal dogs and in dogs with COMS using cine phase contrast MRI. Dogs with COMS were grouped according to severity of syrinx formation. Cine flowMRI imaging was performed in the mid-sagittal and axial planes using a 1.5 Tesla MR scanner (GE Medical Systems®) equipped with a retrospectively graded phase contrast sequence to measure CSF flow velocity throughout the cardiac cycle. Velocity encoding was cranial to caudal. Sixteen image frames per cardiac cycle were evaluated for cranial and caudal flow velocities using a GE Medical Systems® software program. Regions of interest were drawn manually to encompass specific areas of subarachnoid space, syrinx cavities, and cord parenchyma. CSF velocities, ratios of diastolic to systolic flow times, and parenchymal movements were measured. Cine flow MRI was successfully performed on 30 dogs. Flow determinations in the axial plane were more reproducible and reliable than those in the mid-sagittal plane. Axial and sagittal flow was significantly impaired in the region of the cisterna magna and foramen magnum in dogs with COMS compared to normal dogs. In severely affected dogs, reversal of CSF flow was observed during diastole. Caudal movement of the caudal brainstem and cerebellum was significantly greater and more prolonged in dogs with COMS. CSF flow in the ventral subarachnoid compartment was minimally affected. Increased flow gradients were found between more cranial and caudal dorsal subarachnoid spaces in dogs with COMS. In the areas of syrinx formation, flow of CSF in the dorsal subarachnoid space was less impaired but exhibited a longer duration of caudal versus cranial flow. In dogs with moderate to severe COMS, caudal and cranial CSF flow within the syrinx was marked and was equal to flow velocities in adjacent subarachnoid spaces. This study demonstrated that non-invasive cine flow MRI measurements can be performed in dogs and that dogs with COMS have abnormalities of CSF flow and neural tissue shifts during systole and diastole. Magnitudes of some of these changes were correlated with the degree of syrinx formation. This imaging tool may be useful in predicting progression of disease in dogs with COMS and further studies are planned to investigate the role of cine flow MRI in monitoring CSF flow dynamics before and after foramen magnum decompression surgery."

The Use of Ultrasonography to Diagnose “Caudal Occipital Malformation Syndrome” in Dogs – a Prospective Study in 12 Dogs. B Levitin, JJ McDonnell, D Faissler, AS Tidwell. J Vet Intern Med; May/June 2005;19(3) (ACVIM 23rd Ann. Vet. Med. Forum Abstract Program: Abstract 209).

Inherited Occipital Hypoplasia/Syringomyelia in the Cavalier King Charles Spaniel: Experiences in Setting Up a Worldwide DNA Collection.  Rusbridge C., Knowler P., Rouleau G. A., Minassian B. A., and Rothuizen J.  J.Heredity, Jun 2005; 10:1093.

Surgical Management of Combined Hydrocephalus, Syringohydromyelia, and Ventricular Cyst in a Dog.  Hasegawa T., Taura Y., Kido H., Shibazaki, and Katamoto H. J. Am. Anim. Hosp. Assoc., July/August 2005; 41: 267 - 272.

Foramen magnum decompression for treatment of caudal occipital malformation syndrome in dogs. Dewey C.W., Berg J.M., Barone G., Marino D.J., and Stefanacci J.D.  JAVMA, Oct. 2005 ; 227 (8): 1270-1275.

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2006

Syringomyelia and genetic challenges [in Cavalier King Charles Spaniels].  Dunn, T.J., Jr. Dog World, Apr. 2006; 91(4): 14-15.

Bakre skallgropens form hos hund: en studie av occipital hypoplasi hos hund. Spångberg, Camilla. Dept. of Small Animal Clinical Sciences, Swedish University of Agricultural Sciences. Examensarbete (Sveriges lantbruksuniversitet, Fakulteten för veterinärmedicin och husdjursvetenskap, Veterinärprogrammet) vol. 2006:51. Quote: "The aim of the study was to examine whether there is a difference in the shape of the caudal fossa between CKCS, small bred dogs with a similar head shape and dogs with a normal head shape and if occipital bone hypoplasia is related to a head shape with a steep back of the head. Other aims of the study were to examine the crowding of nervous tissue in the foramen magnum in each breed group, the extent of syringohydromyelia and to what extent the malformation had caused neurological signs. ... This study showed that there is a difference in the shape of the caudal fossa between dogs with a normal head shape and small bred dogs with a steep back of the head. This indicates that occipital bone hypoplasia is related to a head shape where the back of the head is steep and that the malformation is common in these breeds. The study also showed that occipital bone hypoplasia not inevitably causes syringohydromyelia. Only one of the dogs with occipital bone hypoplasia or possible bone hypoplasia had had neurological signs that with certainty were related to the malformation. This result gives further support to previous studies that have stated that occipital bone hypoplasia occurs asymptomatic." http://exepsilon.slu.se/archive/00000866/

Syringomyelia: Current Concepts in Pathogenesis, Diagnosis, and Treatment. Clare Rusbridge, Dan Greitz, and Bermans J. Iskandar. J Vet Intern Med; May/June 2006;20(3):469–479. Quote: "Syringomyelia is a condition that results in fluid-containing cavities within the parenchyma of the spinal cord as a consequence of altered cerebrospinal fluid dynamics. This review discusses the history and the classification of the disorder, the current theories of pathogenesis, and the advanced imaging modalities used in the diagnosis. The intramedullary pulse pressure theory (a new pathophysiologic concept of syringomyelia) also is presented. In addition, the current understanding of the painful nature of this condition is discussed and the current trends in medical and surgical management are reviewed."

Morphology of the Caudal Fossa in Cavalier King Charles Spaniels. S Cerda-Gonzalez, NJ Olby, TP Pease,S McCullough, N Massoud, R Broadstone. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 95); Vet. Radiology & Ultrasound, Jan/Feb 2009;50(1):37-46.

Characteristics of Cerebrospinal Fluid Flow in Cavalier King Charles Spaniels. S Cerda-Gonzalez, NJ Olby, TP Pease,S McCullough, N Massoud, R Broadstone. J Vet Intern Med; May/June 2006;20 (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 96).

Foramen Magnum Decompression with Cranioplasty for Treatment of Caudal Occipital Malformation Syndrome in Dogs. CW Dewey, KS Bailey, DJ Marino, G Barone, P Bolognese, TH Milhorat, DJ Poppe. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 267).

Brain Stem Auditory Evoked Response (BAER) Testing in Cavalier King Charles Spaniels with Caudal Occipital Malformation Syndrome. CW Dewey, KS Bailey, G Barone, J Stefanacci. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 270).

Intracranial Epidermoid Cyst and Syringohydromyelia in a Dog. Edward Mackillop, Scott J. Schatzberg, Alexander De Lahunta. Vet. Rad. & Ultra. July-Aug. 2006; 47:339.

Syringomyelia in Cavaliers. Bruce Fogle. Dogs Today, Aug 2006, pg. 56.

Association Between Spinal Cord Dorsal Involvement and Pain in Syringomyelia Secondary to Canine Chiari Malformation. C Rusbridge. H. Caruthers, Marie-Pierre Dube´, M Holmes, N.D. Jeffery. 2006 ESVN Symposium, Abstract #13. J.Vet.Intern.Med. 21(5). Quote: "This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is related to spinal cord dorsal horn damage. Syrinx dimensions and precise location within the spinal cord were determined by masked observers from magnetic resonance images of 55 cavalier King Charles spaniels (CKCS) with syringomyelia. After removal of masking, syrinx parameters were compared between the cohort of dogs that exhibited pain with those that did not. Maximum syrinx width was the strongest predictor of pain in dogs with syringomyelia. Syrinx width was also correlated with scratching behaviour and scoliosis. Syrinx width was strongly correlated with dorsal horn involvement. Dogs with pain were also more likely to have extensive dorsal grey column damage. Large syrinxes with dorsal horn damage are associated with persistent pain which may have implications for the success of surgical and medical management. Our results suggest that the pain behaviour expressed by this group of patients is likely to be ‘neuropathic pain’, resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective."

Coexistence of occipital dysplasia and occipital hypoplasia/syringomyelia in the cavalier King Charles spaniel. C. Rusbridge and S. P. Knowler. J. Small Anim. Prac. Oct. 2006, 47(10):603-606. Quote: "Concurrent occurrence of occipital dysplasia and occipital hypoplasia in two dogs is described in this report. Occipital hypoplasia results in reduced volume of the caudal fossa, leading to overcrowding of the neural structures and, in severe cases, development of syringomyelia. In occipital dysplasia, there is a failure of complete ossification of the supraoccipital bone. When the two conditions occur concurrently, it is possible that syringomyelia may develop more slowly, resulting in presentation with clinical signs in middle to old age. This has implications for screening tests for early detection of syringomyelia, with a view to using the dog for breeding purposes, as dogs with an apparently mild phenotype for occipital hypoplasia/syringomyelia may actually have a more severe genotype. ...  [On post-mortem examination of CKCS and other small breed dogs that the supraoccipital bone overlying the cerebellar vermis is remarkably thin and sometimes eroded so that the foramen magnum is enlarged dorsally]."

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2007

Chiari-like malformation and Syringomyelia in the Cavalier King Charles Spaniel. Clare Rusbridge. PhD. thesis. Utrecht University, Utrecht, The Netherlands. 2007.

New name agreed as international attention focuses on syringomyelia. Clare Rusbridge. Veterinary Times. Apr. 2007.

Association between frontal-sinus size and syringohydromyelia in small-breed dogs. Peter V. Scrivani, Margret S. Thompson, Kevin R. Winegardner, Curtis W. Dewey, Janet M. Scarlett. Am. J. Vet. Research, June 2007, Vol. 68, No. 6, Pages 610-613. Quote: "Our data do suggest, however, that the pathogenesis of syringohydromyelia in small-breed dogs may involve the supratentorial portion of the cranial cavity. We postulate that syringohydromyelia develops in many small-breed dogs and certain breeds in particular as a result of global malformation of the entire cranial cavity or supratentorial portion of the cavity and is not limited to the infratentorial portion of the cranial cavity. If this is true and results can be generalized to the target population, our understanding of the pathogenesis of syringohydromyelia in small-breed dogs and several aspects of clinical management (e.g., screening and diagnostic testing, breeding recommendations for dogs with dome-shaped heads, and treatments) will require further investigation."

Chiari-Like Malformation with Syringomyelia in the Cavalier King Charles Spaniel: Long-Term Outcome After Surgical Management. Clare Rusbridge. Veterinary Surgery 2007 Jul;36(5):396-405. "Cranial cervical decompression surgery is associated with low mortality and morbidity, and results in clinical improvement in most dogs. The procedure seemingly does not result in syrinx collapse and resolution. Clinical improvement may not be sustained and some dogs can be expected to deteriorate."

Report from the Chiari-Like Malformation and Syringomyelia Working Group Round Table. Rodolfo Cappello, organizer, Clare Rusbridge, chairman. Veterinary Surgery 2007 Jul;36 (5), 509–512.

Foramen Magnum Decompression with Cranioplasty for Treatment of Caudal Occipital Malformation Syndrome in Dogs. Curtis W. Dewey, Dominic J. Marino, Kerry S. Bailey, Catherine A. Loughin, Georgina Barone, Paolo Bolognese, Thomas H. Milhorat, Dorothy J. Poppe. Veterinary Surgery 2007 Jul;36 (5), 406–415. "Foramen Magnum Decompression (FMD) with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site."

It's Time. Richard A. LeCouteur. Veterinary Surgery 2007 Jul;36 (5), 390–395. "Medical history is replete with examples of invasive procedures and pharmacologic interventions that were widely accepted based on results of case studies, only to later be rejected based on results of controlled clinical trials. ... It’s time to adopt a more structured scientific approach to the study of the management of neurologic conditions that may benefit from surgical intervention. The randomized (preferably) double-blinded (preferably) placebo-controlled study is the gold standard for evaluating a new treatment intervention."

Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain. C Rusbridge, H Carruthers, M-P Dubé, M Holmes, N D Jeffery. J Small Anim. Pract. 2007 Aug;48(8):432-6. Quote: "Objectives: This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is dependent upon size and involvement of the dorsal part of the spinal cord. Methods: Masked observers determined syrinx dimensions and precise location within the spinal cord on magnetic resonance images of 55 cavalier King Charles spaniels with syringomyelia. After removal of masking, syrinx size and location were compared between the cohorts of dogs that exhibited pain with those that did not. Results: Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord. Clinical Significance: Large syrinxes associated with damage to the dorsal part of the spinal cord are associated with persistent pain suggesting that the pain behaviour expressed by this group of patients is likely to be 'neuropathic pain', resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective."

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2008

Amantadine in a multimodal analgesic regimen for alleviation of refractory osteoarthritis pain in dogs. B.D.X. Lascelles, J.S. Gaynor, E.S. Smith, S.C. Roe, D.J. Marcellin-Little, G. Davidson, E. Boland, J. Carr. J. Vet. Intern. Med. January 2008;22(1):53-59. Quote: Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) do not always provide sufficient pain relief in dogs with osteoarthritis (OA). Hypothesis: The use of amantadine in addition to NSAID therapy will provide improved pain relief when compared with the use of nonsteroidal analgesics alone in naturally occurring OA in dogs. Animals: Thirty-one client-owned dogs with pelvic limb lameness despite the administration of an NSAID. Methods: The study was randomized, blinded, and placebo controlled with parallel groups (days 21–42). On day 0, analgesic medications were discontinued. On day 7, all dogs received meloxicam for 5 weeks. On day 21, all dogs received amantadine (3–5 mg/kg once daily per os) or placebo for 21 days, in addition to receiving meloxicam. Assessments were performed before the study and on days 7, 21, and 42. Primary outcome measures were blinded owner assessments of activity using client-specific outcome measures (CSOM) on days 0, 7, 21, and 42. Data were analyzed by a mixed model approach. Results: For CSOM activity, there was a significant time by treatment effect (P 5.009). On the basis of the planned post hoc t-tests of postrandomization means, there was a significant difference between treatment groups on day 42 (P 5.030), with the amantadine group being more active. Conclusions and Clinical Importance: In dogs with osteoarthritic pain refractory to an NSAID, physical activity is improved by the addition of amantadine. Amantadine might be a useful adjunct therapy for the clinical management of canine osteoarthritic pain.

Radiographic morphology of the cranial portion of the cervical vertebral column in Cavalier King Charles Spaniels and its relationship to syringomyelia. Catherine E. Stalin, Clare Rusbridge, Nicolas Granger, and Nick D. Jeffery.. Am J Vet Res. 2008 Jan;69(1): 89-93. Quote: "Results suggested that radiographic morphology of the atlantoaxial region in CKCSs differs from morphology of that region in dogs of other breeds, but that these differences do not account for why some CKCSs develop syringomyelia and others do not."

Pathophysiology and treatment of neuropathic pain associated with syringomyelia. Clare Rusbridge and Nick D. Jeffery.  Vet. J. 2008 Feb; 175(2): 164-172. Quote: "The pain behaviour expressed by dogs with syringomyelia suggests that they experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication will be ineffective. In this review, physiological and pathological pain processing through the dorsal horn is summarised and mechanisms by which syringomyelia could result in a persistent pain state are discussed. Finally, current knowledge regarding treatment of Chiari malformation and syringomyelia is reviewed and possible drugs which may give improved pain relief in affected dogs are discussed."

A Practical Guide to Canine and Feline Neurology. Curtis W. Dewey. John Wiley & Sons; 2008; 4-6,129. Quotes: ""Breed-associated neurologic abnormalities of dogs and cats. ... Cavalier King Charles Spaniels ... Caudal occipital malformation syndrome (with syringohydromyelia) " pp. 4-6. ""Caudal occipital malformation syndrome is the canine analog of Chiari type I malformation of people. Although only recently described in dogs, COMS appears to be a very common neurologic disorder in this species. This disease is almost exclusive to small breed dogs, with the Cavalier King Charles Spaniel (CKCS) being the most overrepresented." p. 129.

Treatment of canine Chiari-like malformation and syringomyelia. Dewey, C., Rusbridge, C. In: Kirk’s Current Veterinary Therapy XIV, 14th Ed. Bonagura, J., Twedt, D. (Eds.),  Saunders, 2008 pp. 1102–1108.

Caudal Occipital Malformation Syndrome in Cavalier King Charles Spaniels. C.W. Dewey. ACVIM 2008.

Ultrasonographic Appearance of the Craniocervical Junction in Normal Brachycephalic Dogs and Dogs with Caudal Occipital (Chiari-like) Malformation. Martin J. Schmidt, Antje Wigger, Sebastian Jawinski, Tanja Golla, Martin Kramer. Vet. Radiology & Ultrasound. Aug 2008; 49(5): 472 - 476. Quote: "Ultrasonographic evaluation of the spine, especially of the spinal cord, has been rarely reported in dogs. The atlanto-occipital junction provides a small acoustic window through which examination of the craniocervical transition can be performed. Normal sonographic findings of this region in 10 normal brachycephalic dogs are presented and compared with sonographic findings from 25 Cavalier King Charles Spaniels with the caudal occipital malformation syndrome. Sonographic findings were compared with magnetic resonance imaging findings to determine the extent of cerebellar herniation and syringohydromyelia. Cerebellar displacement into the foramen magnum was clearly identified sonographically; however, syringohydromyelia was not discernable due to bone overlay."

Chiari-like malformation and syringomyelia in normal cavalier King Charles spaniels: a multiple diagnostic imaging approach. J. Couturier, D. Rault, L. Cauzinille. J Small Anim. Pract. 2008 Sept; 49(9):438-443.  Quote: "Results: Of the 16 [CKCS] dogs in the study, 7 had syringomyelia (43.7%). All dogs had cerebellar herniation, suggesting Chiari-like malformation and also a tendency to occipital dysplasia. Computed tomography measurements of the caudal fossa are reported. In one dog, a syrinx was identified by ultrasonography. The only difference between dogs with or without syringomyelia was that dogs with Chiari-like malformation/syringomyelia were statistically older. Clinical Significance: The incidence of Chiari-like malformation and syringomyelia may be high in an asymptomatic population of cavalier King Charles spaniel. Computed tomography measurements reported in this study should now be compared with those of a symptomatic population to evaluate the hypothesis that dogs with Chiari-like malformation/syringomyelia syndrome have a smaller caudal fossa. This study did not identify a smaller caudal fossa in an asymptomatic cavalier King Charles spaniel population with syringomyelia. Ultrasonography probably has a low sensitivity for diagnosis of Chiari-like malformation/syringomyelia."

Intermittent "greeting" due to Chiari-like malformation/syringomyelia (CM/SM) and occipital dysplasia in a Cavalier King Charles Spaniel. Balthen-Nothen, A., Bull, C., Fehr, M., Fork, M., Tipold, A. Tieraerztliche Praxis Ausgabe Kleintiere Heimtiere 2008; 36(2):119-125. Quote: "A 5.5-year-old male Cavalier King Charles Spaniel (CKCS) was presented with an intermittent gait abnormality of one front limb. During these episodes the dog flexed one front limb for some minutes like a kind of 'greeting'. Between these episodes the dog's gait was normal. Neurological examination the neuroanatomical localization was considered to be primarily in the upper motor neuron of the cervical spine. As a diagnostic imaging tool, a magnetic resonance imaging (MRI) of the brain, cervical and thoracic spinal cord was performed and the area of the foramen magnum was shown by computed tomography. Results: In this patient a moderate herniation of the cerebellum and severe syringohydromyelia of the cervical and thoracic spinal cord (Chiari-like malformation and syringomyelia; CM/SM) was diagnosed. The foramen magnum was dorsally widened in a keyhole shape. As therapy of the syringohydromyelia a dorsal laminectomy at the level of the first cervical vertebra with fenestration of the dura mater was performed. Up to a post surgery follow-up eight weeks later, the dog no longer showed 'greeting', although in a repeated MRI the dimensions of the syrinx still remained. Conclusion: Many neurologic signs are described in association with a syrinx. This is the first case report of a CKCS presenting intermittent 'greeting'. Furthermore the dog showed a combination of two anomalies: Chiari-like malformation and syringomyelia (CM/SM) and occipital dysplasia. Clinical relevance: It is recommended that the CKCS should be screened for breeding purposes not only for occipital hypoplasia but also for occipital dysplasia. A surgical decompression of the cerebrospinal fluid-filled space can result in resolution of clinical signs, whereas MRI failed to demonstrate an improvement of the syrinx. Further studies with advanced MRI techniques would be necessary in the future to diagnose morphologic as well as functional options of the cerebrospinal fluid-filled space and -flow."

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2009

Morphology of the Caudal Fossa in Cavalier King Charles Spaniels. Sofia Cerda-Gonzalez, Natasha J. Olby, Susan McCullough, Anthony P. Pease, Richard Broadstone, Jason A. Osborne. Vet. Radiology & Ultrasound, Jan/Feb 2009;50(1):37-46.  Quote: "Chiari malformations and syringohydromyelia are an important disease complex in Cavalier King Charles Spaniels. Although abnormalities in caudal fossa morphology are considered major contributors to the development of this disease, limited information exists on the range of morphologies in Cavalier King Charles Spaniels and on the relationship of these to clinically evident disease. Sixty-four Cavalier King Charles Spaniels were studied. Each underwent a neurologic examination and magnetic resonance imaging of the cervical spine and brain. T2-weighted sagittal images were used to determine both the morphologic characteristics and volume of the caudal fossa in each dog. This volume was also analyzed as a percentage of total cranial cavity volume. Each attribute was correlated with neurological grade and presence of syringohydromyelia. Fifteen dogs had neurologic signs, and 59 had morphologic abnormalities of the craniocervical junction. While 27 dogs had syringohydromyelia, 13 of these were clinically normal. Cerebellar herniation and occipital dysplasia were common findings but were not associated with syringohydromyelia. Dorsal compressive lesions were noted at the first and second cervical vertebral junction. Factors associated with the presence of neurologic signs included syringohydromyelia and the ratio of caudal fossa/total cranial cavity volume; dogs with signs had significantly larger syringohydromyelia than asymptomatic dogs. Caudal fossa size was not associated with syringohydromyelia. A positive association was identified between foramen magnum size and length of cerebellar herniation. The prevalence of craniocervical junction abnormalities is high in Cavalier King Charles Spaniels. While several factors are associated with neurologic signs, occipital hypoplasia appears to be the most important factor."

Clinical diagnosis and treatment of suspected neuropathic pain in three dogs. RG Cashmore, TR Harcourt-Brown, PM Freeman, ND Jeffery, N Granger. Australian Vet. J. January 2009;87(1&2):45-50. Quote: Three dogs were referred to The Queen’s Veterinary School Hospital at University of Cambridge for chronic behavioural or locomotor disorders associated with pain. All three had been unsuccessfully treated with conventional analgesics, including non-steroidal anti-inflammatory drugs, glucocorticoids and opiate agonists, prior to referral, with minimal or no response. They were investigated by neurological examination plus conventional ancillary diagnostic tests and therapeutic drug trials. Ruling out other causes of pain and applying previously well-described criteria, each case was diagnosed as consistent with neuropathic pain, a poorly recognised condition in domestic dogs. ... Apparent allodynia and dysaesthesia have been reported in Cavalier King Charles Spaniels suffering from Chiari-like malformation with syringomyelia. These animals often dislike contact of the skin on their necks and typically exhibit ‘phantom’ scratching, which are consistent with allodynia and dysaesthesia, respectively. Apparent mechanoallodynia, hyperalgesia, and dysaesthesia were prominent clinical features observed in all three dogs in this report. ... Treatment with the tricyclic antidepressant drug, amitriptyline, or the antiepileptic drug, gabapentin, resulted in either a dramatic improvement or full resolution of clinical signs in all cases.

Use of magnetic resonance imaging for morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels. Carrera I, Dennis R, Mellor DJ, Penderis J, Sullivan M. Am J Vet Res; 2009 Mar;70(3):340-5. Quote: "Objective-To perform morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels (CKCSs), to assess the relationship between caudal fossa dimensions and the frequency of magnetic resonance imaging (MRI) features of occipital abnormalities in CKCSs (with and without syringomyelia), and to compare caudal cranial fossa measurements in CKCSs with measurements of 2 groups of mesaticephalic dogs. Animals-70 CKCSs and 80 mesaticephalic (control) dogs. Procedures-Dogs were placed into 4 groups as follows: Labrador Retrievers (n = 40), spaniel-type dogs (40; English Springer Spaniels and Cocker Spaniels), CKCSs with syringomyelia (55), and CKCSs without syringomyelia (15). Multiple morphometric measurements (linear, angular, and area) were obtained from cranial midsagittalT2-weighted magnetic resonance images including the brain and cervical portion of the spinal cord. Several specific MRI findings were also recorded for CKCSs that appeared to affect the occipital bone and cervicomedullary junction. Results-No significant difference was identified among breeds in control groups and between sexes in any of the groups for all morphometric measurements. Significant differences were identified in CKCSs, compared with mesaticephalic dogs, in the area of the caudal cranial fossa and for several linear measurements that reflected the length of the ventral aspect of the occipital bone. These differences were greater in CKCSs with syringomyelia. All CKCSs had abnormalities in occipital bone shape. Conclusions and Clinical Relevance-CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."

Evaluation of the volumes of cranial cavities in Cavalier King Charles Spaniels with Chiari-like malformation and other brachycephalic dogs as measured via computed tomography. Schmidt MJ, Biel M, Klumpp S, Schneider M, Kramer M. Am J Vet Res. 2009 Apr;70(4):508-12. Quote: "Objective-To measure the absolute and relative volumes of cranial vaults of Cavalier King Charles Spaniels (CKCSs) and other brachycephalic dogs for the purpose of evaluating a possible association between the volume of the caudal fossa (fossa caudalis cerebri; CF) and existence of Chiari-like malformation (CLM) and syringohydromyelia in CKCSs. Animals-40 CKCSs and 25 brachycephalic dogs. Procedures-The intracranial vault of all dogs was evaluated via computed tomography followed by magnetic resonance imaging. Volumes of the CF and the rostral and medial fossa (fossa rostralis et medialis cerebri) were determined. The ratio of the absolute volumes was calculated as the volume index (VI). Results-All CKCSs had cranial characteristics consistent with CLM. There were no significant differences between CKCSs and brachycephalic dogs with respect to the VI and absolute volumes of the CF and rostral and medial fossas. The CKCSs without syringohydromyelia (n = 26) had a median VI of 0.1842, and CKCSs with syringohydromyelia (14) had a median VI of 0.1805. The median VI of other brachycephalic dogs was 0.1864. The VI did not differ among these 3 groups. Conclusions and Clinical Relevance-Results of this study suggested that descent of the cerebellum into the foramen magnum and the presence of syringohydromyelia in CKCSs are not necessarily associated with a volume reduction in the CF of the skull."

Imaging features of atlanto-occipital overlapping in dogs. Cerda-Gonzalez S, Dewey CW, Scrivani PV, Kline KL. Vet. Radiology Ultrasound. May 2009;50(3):264-268. Quote: "The imaging features of four dogs with atlanto-occipital overlapping are described. This malformation appeared to play a role in the development of neck pain, ataxia, variable cerebellar involvement, medullary kinking, and possibly syringomyelia. Using cervical radiographs, three of the four dogs were initially diagnosed with an atlanto-axial malformation. Because this disorder could not account for all clinical signs, magnetic resonance and computed tomography images were also acquired. These provided a more complete evaluation of the craniocervical junction, allowing detection of atlanto-occipital overlapping, medullary kinking, occipital dysplasia, abnormalities of the dens, and syringomyelia in these dogs. Head position during imaging affected the degree of atlanto-occipital overlap. These findings emphasize the need to modify the currently accepted imaging recommendations for dogs with head and neck pain and/or cranial cervical myelopathy. We suggest that the entire craniocervical junction be evaluated, even if atlanto-axial subluxation has already been detected. Moreover, we propose that atlanto-occipital overlapping is a perhaps underrecognized disorder that can influence the clinical signs and therapeutic outcome of dogs with anomalies of the craniocervical junction."

Muscular dystrophy in Cavalier King Charles spaniels. Piercy, Richard. J. and Walmsley, Gemma. Vet Rec. 2009 165 (2), p. 62. Quote: "We have recently identified the genetic cause of a form of muscular dystrophy in CKCS. The causative mutation is in the dystrophin gene and the X-linked disease is associated with weakness, muscle atrophy and exercise intolerance, detectable from a few months of age. Prominent signs in affected dogs are dysphagia [the symptom of difficulty in swallowing] and macroglossia (enlarged tongue)[tongue enlargement that leads to functional and cosmetic problems]. Serum creatine kinase is usually markedly elevated. Male dogs with the mutation [are] clinically affected and female dogs with the mutation are silent carriers. We are also keen to hear from veterinary surgeons who believe they may have seen an affected dog in their practice, in order to estimate the prevalence of this disease and limit its spread by genetic testing."  Contact Dr. Piercy at the Royal Veterinary College's Comparative Neuromuscular Diseases Laboratory at rpiercy@rvc.ac.uk

Does size matter? The continuing riddle of Chiari and syringomyelia. Simon R. Platt, Marc Kent, and Scott J. Schatzberg. J Small Anim. Pract. 2009 Aug; 50(8):383-384.

Association between cervical and intracranial dimensions and syringomyelia in the cavalier King Charles spaniel. H. Carruthers, C. Rusbridge, M.-P. Dubé, M. Holmes, and N. Jeffery. J Small Anim. Pract. 2009 Aug; 50(8):394-398. Quote: "Objectives: To investigate the possible association between caudal fossa area and cervical vertebral dimensions and the presence of syringomyelia in cavalier King Charles spaniels. Methods: From magnetic resonance imaging scans of 78 cavalier King Charles spaniels, measurements were made of the widest vertical spinal width at C1/C2, C2, C2/C3 and C3; angulation of the C2/C3 spine; and estimated caudal fossa area. A correlation between these measurements and syringomyelia was sought. Results: A total of 59 dogs with and 19 without syringomyelia were compared. Older dogs had a significantly higher incidence of syringomyelia. No difference in incidence was noted between genders. There was no significant difference in vertebral canal width at C1/C2 and C2, or angulation of C2/C3 between syringomyelia and non-syringomyelia groups. The width of the canal at C2/C3 and C3 was significantly increased in syringomyelia dogs. There was no significant difference in the caudal fossa area between groups. Clinical Significance: Although syringomyelia was shown to be more prevalent in older dogs, the age beyond which dogs were considered at greater risk was not deducible from the dataset. The association identified between wider spinal canal at C3, and C2/C3 and syringomyelia presence is of questionable clinical significance, as the difference between syringomyelia and non-syringomyelia groups is too small to be measured in a clinical setting."

Chiari-like malformation in the Griffon Bruxellois. C. Rusbridge, S. P. Knowler, L. Pieterse, and A. K. McFadyen. J Small Anim. Pract. 2009 Aug; 50(8):386-393.  Quote: "It should also be realised that although this study found a method of predicting CM in the [Griffon Bruxellois], this may not be transferable to other breeds. This may be especially true for the CKCS where CM is almost ubiquitous ... ."

Comparison of cerebral cranium volumes between cavalier King Charles spaniels with Chiari-like malformation, small breed dogs and Labradors. H. R. Cross, R. Cappello, and C. Rusbridge.  J Small Anim. Pract. 2009 Aug; 50(8):399-405  Quote: "Objectives: To ascertain whether cavalier King Charles spaniels (CKCSs) have a proportionately smaller caudal fossa compared with other small dogs and with Labradors.  ... Labradors were chosen as a 'control' group because their skull is relatively dolichocephalic and a large database of MRI scans was available. ... To evaluate if cerebellar herniation in CKCS correlates with caudal fossa volume. Methods: In this retrospective study, three-dimensional images were created from magnetic resonance imaging brain series of 117 dogs (split into three groups: CKCS, Labradors and small breeds) from which the volumes of the fossae and brain parenchyma were calculated. These volumes were transformed into percentages of total cranial cavity and parenchyma volumes, respectively. The percentages were statistically compared among the groups. The percentage of herniated cerebellum in the CKCS was compared using linear regression with the caudal fossa and parenchyma percentages. Results: ... When compared with Labradors, CKCS had proportionately the same volume of parenchyma in their caudal fossa, hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. This supports either theory of pathogenesis of CM as mesoderm insufficiency during embryology − causing insufficient scope for the mesoderm and ectoderm layers to develop ... − or alternatively premature growth plate closure. Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds. Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM. From this study, all CKCS are at an increased risk of showing cerebellar distortion visible on MRI scans due to caudal fossa overcrowding, but the volume measurements are unable to predict cerebellar herniation which may be influenced by other skull abnormalities like occipital dysplasia resulting in a wider FM ... . Furthermore, RI scans of young CKCS may not help to predict the development of SM in later life as a complication to CM. Therefore, it is necessary for further studies to be conducted in order to investigate correlations between cranium volumes and disease progression and clinical signs."

Characteristics of Cerebrospinal Fluid Flow in Cavalier King Charles Spaniels Analyzed Using Phase Velocity Cine Magnetic Resonance Imaging. Sofia Cerda-Gonzalez, Natasha J. Olby, Richard Broadstone, Susan McCullough, Jason A. Osborne. Vet. Rad. & Ultrasound, Sep/Oct 2009, 50(5):467-476. Quote: "Syringomyelia is an important morbidity source in Cavalier King Charles Spaniels. Although abnormal cerebrospinal fluid (CSF) flow secondary to Chiari malformations is thought to cause syringomyelia in humans, this relationship is unknown in dogs. We used phase-contrast magnetic resonance (MR) imaging to evaluate CSF flow in dogs. Fifty-nine Cavalier King Charles Spaniels were assigned a neurologic grade reflecting their neurologic status. Five normal control dogs of other breeding were imaged for comparison. The presence of syringomyelia was noted from sagittal MR images. The pattern and velocity of CSF flow were assessed using phase-contrast cine MRI at the foramen magnum, C2–C3 disc space, and within syrinxes. Flow was measured most easily with the neck flexed to mimic standing. CSF flow velocity in the dorsal aspect of the subarachnoid space at the foramen magnum was significantly higher in control dogs than Cavalier King Charles Spaniels. Flow was obstructed at the foramen magnum in 41 of 59 Cavalier King Charles Spaniels. Turbulent flow and jets were associated with syringomyelia presence and severity, and CSF flow velocity at C2/3 dorsally was inversely related to the presence of syringomyelia. Peak dorsal subarachnoid space CSF flow velocity at the foramen magnum and C2–C3 were together highly predictive of syringomyelia. CSF flow can be assessed in dogs using phase-contrast cine MRI. Obstruction to flow at the foramen magnum is common in Cavalier King Charles Spaniels and CSF flow pattern and velocity are related to the presence of syringomyelia."

Volumetric Analysis Of Brain Parenchyma Within The Caudal Fossae Of Cavalier King Charles Spaniels.  C Driver, C Rusbridge, H Cross, HA Volk. 22nd ECVN Annual Symposium, Sept. 2009; J Vet Intern Med, Jan/Feb 2010;24(1):242. Quote: "Chiari-like malformation (CM) and syringomyelia (SM) is a debilitating disease complex recognized in the Cavalier King Charles Spaniel (CKCS). Mesoderm insufficiency during embryogenesis has been suggested as the pathogenesis of Chiari type-I malformations in humans leading to a small posterior fossa but a normally developed hindbrain. No volumetric evidence exists regarding the role of hindbrain volume within the caudal fossa in the development of SM in dogs. Magnetic resonance (MR) images of 59 CKCS with CM and no other systemic disease were retrospectively reviewed. ... Volumes of hindbrain parenchyma were analyzed as percentages of caudal fossa volume and caudal fossa volume was analyzed as a percentage of total cranial cavity volume. The volume of the ventricular system was recorded as a percentage of total parenchymal volume. If SM was present, syrinx size was measured from T2 weighted MR images from the maximal dorsoventral dimension within the cervical spine. SM was present in 40/59 (68%) dogs. All data was normally distributed. There was no significant (t-test, p=5 0·702) age difference between dogs with (61.2 ± 33.8 months; 6.8–128.9) or without SM (57.4 ± 37.1 months; 3.9–122.8). Caudal fossa percentage of the total cranial cavity volume did not differ significantly (t-test, p=5 0·520) between dogs without (14.4 ± 1.5%) or with (14.9 ± 1.3%) SM. However, there was a significant difference (p=50·002) between the two groups looking at hindbrain parenchyma percentage of the caudal fossa (86.7 ± 4.1% and 89.9 ± 1.67% respectively). Furthermore, in the SM group a significant positive association was found between the hindbrain parenchyma percentage and syrinx size (spearman r=5 0·437). No significant difference (p=5 0·164) was found between the two groups for ventricular volume (5.30 ± 7.68% and 7.73 ± 5.36% respectively), however when a syrinx was present a strong positive correlation was found between ventricular and syrinx size (spearman r=5 0·500). This work supports recent evidence that caudal fossa size is not associated with SM, but that overcrowding of the caudal fossa leads to SM and may be caused by mesoderm insufficiency. The association between ventricle and syrinx dimensions supports the theory that SM develops as a result of altered CSF dynamics."

Anatomical Distribution of Syringomyelia in Cavalier King Charles Spaniel With Chiari.Like Malformation. S Loderstedt, L Benigni, K Chandler, C Lamb, C Rusbridge, HA Volk. 22nd ESVN Annual Symposium, Sept. 2009; J Vet Intern Med, Jan/Feb 2010;24(1):253. Quote: "The objective of this study was to evaluate the prevalence and anatomical distribution of syringomyelia (SM) in clinically-affected CKCS. It was hypothesised that (1) SM is not restricted to the cervical region of the spine, (2) the maximal syrinx diameter can occur anywhere along the spinal cord, (3) there is an association between cervical syrinx diameter and distribution and SM in other regions of the spinal cord. Thirty-seven CKCS with clinical evidence of SM were studied prospectively. Magnetic resonance (MR) imaging of the brain and the entire spinal cord of each dog were performed at 1.5 Tesla. ... SM was not limited to the cervical region. SM was present in the region of the C1-C4 vertebral bodies in all dogs (100%) however it often was not limited to that area being also found at C5- T1 in 31/37 (84%), T2-L2 in 29/37(78%) and L3-L6 in 21/37 (57%). Maximal SM diameter occurred at C1-C4 in 19/37 (51%) dogs, at C5- T1 in 2/37 (5%), at T2-L2 in 15/37 (41%) and at L3-L6 in 1/37(3%) dogs, respectively. There was no significant difference between the mean syrinx diameter at the region C1-C4, C5- T1 and T2-L2 but mean syrinx diameter was less in the region L3-L6. Mean syrinx diameter at C1-C4 was positively correlated with mean syrinx diameter at C5- T1, T2-L2 and L3-L6 respectively. Many CKCS with a cranial cervical syrinx also have a syrinx affecting more caudal regions of the spinal cord. Dogs with a large cranial cervical syrinx tend to also have a large syrinx more caudal. MR imaging restricted to the cervical region will underestimate the extent of the syrinx and the severity of the disease process in the majority of dogs."

Atlanto-Occipital OverlappingSurgical Stabilization of a Craniocervical Junction Abnormality With Atlanto-Occipital Overlapping in a Dog. Curtis W. Dewey, Sofia Cerda-Gonzalez, Peter V. Scrivani, Andrea. Looney, Gena M. Silver. Compendium Vet. October 2009. E1-E6, Quote: "A 3-year-old male neutered Pomeranian presented with severe, poorly localizable pain that was unresponsive to a combination of oral medications (gabapentin, tramadol, prednisone, and methocarbamol) and a fentanyl patch. A Chiari-like malformation with associate syringomyelia was evident on magnetic resonance imaging (MRI). In addition, overlapping of the dorsal arch of C1 and the dorsal aspect of the foramen magnum was suspected from the MRI scans and verified via computed tomography (see image at right), suggesting a condition similar to basilar invagination/impression in people. At surgery, a combination of foramen magnum decompression with cranioplasty and stabilization of the atlanto-occipital junction was performed. The atlanto-occipital junction was stabilized using an adaptation of a procedure used in people for basilar invagination/impression. Over the next several months, the dog's clinical signs improved dramatically, allowing substantial reduction of oral pain medications. This is the first report of surgical stabilization for atlano-occipital overlapping in a dog."

Foramen Magnum Decompression with Free Autogenous Adipose Tissue Graft for Treatment of Caudal Occipital Malformation Syndrome in Dogs. Erin Y. Akin, Nora H. Ortinau, Andy Shores, M. B. Carnes, Jill Narak. 2009 ACVS Vet. Symposium Abstract. Quote: "The objective of this study was to describe and evaluate a modified surgical technique using foramen magnum decompression (FMD), durotomy, duroplasty with swine intestinal submucosa (SIS), and a free autogenous adipose tissue graft (FAATG) for the treatment of canine caudal occipital malformation syndrome (COMS). Fourteen client-owned dogs with MRI evidence of COMS and surgical treatment with FMD were included in this 18-month prospective study (10/07 – 3/09). Breeds treated included Cavalier King Charles Spaniel (11), Chihuahua (2), and Pomeranian (1). Surgical decompression of the foramen magnum and durotomy were performed in a fashion similar to previously described techniques. ... The dura was marsupialized, suturing it to the surrounding fascia using simple interrupted sutures of 5-0 polydioxanone (fig 3). The SIS was sutured to the dura in a tent-like fashion using simple interrupted sutures of 5-0 polydioxanone. The FAATG, typically obtained from the gluteal region, was placed over the defect followed by a sheet of gelatin foam. ... Overall, recovery was considered to be good to excellent by owners. To date, none of the patients that have undergone this surgical procedure have required further surgical intervention due to postoperative compressive scar formation that has been reported in the previous literature. ... In dogs that require FMD in the treatment of COMS, this modified technique using a FAATG should be considered. Current clinical outcomes of patients that were treated for COMS using this technique showed excellent results similar to current published literature without intraoperative complications and clinical improvement with a decrease in clinical signs postoperatively. The use of the titanium mesh, placement of the screws, and the exothermic reaction of the overlying methyl methacrylate may contribute to tissue trauma. The authors conclude that with the results of this study, this procedure is clinically effective and the use of a titanium mesh, additional hardware and methyl methacrylate offers no advantage in canine COMS patients."

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2010

Congenital Diseases of the Craniocervical Junction in the Dog. Sofia Cerda-Gonzalez, Curtis W. Dewey. Vet. Clinics: Small Animal Pract. January 2010;40(1):121-141. Quote: "Craniocervical junction disorders are most frequently seen in toy and small-breed dogs. They can present a diagnostic challenge, as multiple anomalies can be present concurrently and share similar clinical manifestations. Some, such as Chiari-like malformations, may be present in asymptomatic dogs. A thorough evaluation of the entire craniocervical junction, frequently using more than 1 imaging modality, is necessary before making treatment decisions. ... The craniocervical junction (also known as the craniovertebral junction) consists of the occipital bone, foramen magnum, atlas, axis, and the ligament of the atlantoaxial and atlantooccipital junctions. It functions as a single unit to provide support and movement of the head in relation to the body. The craniocervical junction is united by a single, continuous, joint cavity, which includes the atlantooccipital and atlantoaxial junctions and a fluid-filled cavity separating the dens and the body of the atlas. The atlantooccipital junction is further stabilized by dorsal and ventral atlantooccipital membranes, bilateral lateral atlantooccipital ligaments, and ligaments extending from the body of the atlas to the foramen magnum. This junction allows lateral and dorsoventral movement of the head in relation to the cervical spine. The atlantoaxial junction, in turn, is stabilized by the dorsal atlantoaxial ligament and the transverse atlantal ligament. The apical and alar ligaments extend cranially from the dens to the occiput, spanning the atlantoaxial and atlantooccipital junctions. The atlantoaxial junction primarily permits rotational movement of the head. The occipital bone is divided into 3 components: the supraoccipital bone, the exocciput, and the basiocciput. The supraoccipital bone surrounds the foramen magnum, the occipital conndyles arise from the exoccipital bone, and the basiocciput forms the base of the skull."

Heritability of syringomyelia in Cavalier King Charles spaniels. Tom Lewis, Clare Rusbridge, Penny Knowler, Sarah Blott, John A. Woolliams. Vet.J. 183(3): 345-347 Mar. 2010. Quote: "Mixed model analysis of 384 Cavalier King Charles spaniels (CKCS), with a magnetic resonance imaging diagnosis for the presence or absence of a syrinx, in conjunction with the Kennel Club pedigree records of all dogs registered from the mid 1980s to September 2007, revealed a moderately high estimate of heritability of syringomyelia (h2 = 0.37 ± 0.15 standard error) when analysed as a binary trait. Inspection of cases where the disease segregated within families pointed to genes at more than one locus influencing syringomyelia. The availability of estimated breeding values for Kennel Club registered CKCS is a significant step in being able to select against syringomyelia, particularly given the difficulty of ascertaining the disease phenotype."

Syringomyelia in the Cavalier King Charles spaniel (CKCS) dog. Katheryn C. Wolfe, Roberto Poma. Can Vet J;51:95-102; Jan 2010. Quote: "Recent data suggest that CM in the Cavalier King Charles spaniel (CKCS) is inherited. The incidence of CM in the CKCS breed is an estimated 95% and current studies suggest that SM is present in more than 50% of dogs with CM with approximately 35% of affected dogs exhibiting clinical signs. ... Overall, the prognosis for CM/SM-affected dogs depends on the severity of clinical signs and on the response to medication. Chiari-like malformation and syringomyelia is a progressive condition in those dogs that are affected clinically. Some dogs will need constant dose adjustments to adequately treat their symptoms. Unfortunately, some dogs afflicted with severe and disabling pain do not respond to medical management and are not surgical candidates, in which cases a thorough evaluation of their quality of life is necessary."

Optimisation of breeding strategies to reduce the prevalence of inherited disease in pedigree dogs. Lewis, T.W.; Woolliams, J.A.; Blott, S.C. Animal Welfare 19(Supp 1):93-98(6), May 2010. Quote: "One option for improving the welfare of purebred dog breeds is to implement health breeding programmes, which allow selection to be directed against known diseases while controlling the rate of inbreeding to a minimal level in order to maintain the long-term health of the breed. The aim of this study is to evaluate the predicted impact of selection against disease in two breeds: the Cavalier King Charles spaniel (CKCS) .... Heritabilities for mitral valve disease, syringomyelia in the CKCS ... were estimated to be 0.64 (± 0.07), 0.32 (± 0.125) ... respectively, which suggest encouraging selection responses are feasible based upon the estimation of breeding values (EBVs) if monitoring schemes are maintained for these breeds. Although using data from disease databases can introduce problems due to bias, as a result of individuals and families with disease usually being over-represented, the data presented is a step forward in providing information on risk. EBVs will allow breeders to distinguish between potential parents of high and low risk, after removing the influence of life history events. Analysis of current population structure, including numbers of dogs used for breeding, average kinship and average inbreeding provides a basis from which to compare breeding strategies. Predictions can then be made about the number of generations it will take to eradicate disease, the number of affected individuals that will be born during the course of selective breeding and the benefits that can be obtained by using optimisation to constrain inbreeding to a pre-defined sustainable rate."

Genome wide linkage studies identifies a novel locus for syringomyelia associated with Chari-like malformation in the Cavalier King Charles Spaniels. Quoc-Huy Trink, Penny Knowler, Alexandra Thibault, Marie-Pierre Dubé, Guy A. Rouleau, Clare Rusbridge, and Zoha Kibar. May 20, 2010.

Relationship of brain parenchyma within the caudal cranial fossa and ventricle size to syringomyelia in cavalier King Charles spaniels. C. J. Driver, C. Rusbridge, H. R. Cross, I. McGonnell, and H. A. Volk. J Small Anim. Pract.; July 2010; 51(7):382-386 Quote: "Objectives: To assess if the volumes of the caudal cranial fossa (CCF), parenchyma within the caudal cranial fossa (CCFP) or ventricles (V) are associated with syringomyelia (SM) in cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM). To evaluate if volumes are associated with transverse syrinx width. Methods: Magnetic resonance images of 59 CKCS with CM were retrospectively reviewed and grouped with or without SM. Three-dimensional images were created and volumes of the fossae, brain parenchyma and ventricular system were calculated from which percentages of CCF, CCFP and V were created. If present, syrinx size was measured from its maximal transverse width. The percentages were statistically compared between groups, and correlation between percentages and syrinx dimensions was made. Results: CKCS with SM had significantly higher CCFP (P=0·0001) and V (P=0·0002) to those without but no significant difference in CCF (P=0·925). There was a positive correlation between CCFP and syrinx width (Pearson r=0·437) and ventricle size to syrinx width (Spearman r=0·627). Clinical Significance: A more marked overcrowding of the CCF is associated with SM, which may explain the high incidence of SM in CKCS with CM. The association between ventricle and syrinx dimensions supports the theory that SM development is the result of altered cerebrospinal fluid dynamics."  See also: Volumetric Analysis Of Brain Parenchyma Within The Caudal Fossae Of Cavalier King Charles Spaniels, above.

Canine Chiari-like Malformation: A Comparison of Ventricular and Caudal Fossa Volumes in Cavalier King Charles Spaniels > 5 years of age that have not developed Syringomyelia vs those Affected when < 2 years. C Driver, C Rusbridge, HA Volk. Abstract at 2010 BSAVA conference.  MRIs of 21 Cavalier King Charles spaniels under 2 years affected with CM/SM, and 14 CKCSs over 5 years with only CM were analyzed.  Conclusion: Severe SM in Cavaliers under 2 years old is associated with greater mis-match between hindbrain and caudal fossa volume than found in older CKCSs with CM but no SM. They also measured the dimensions of the brain's ventricle cavities of SM-affected Cavaliers, and they found that the ventricle volumes had a direct correlation with the width of the syrinx.

Transcranial Magnetic Motor Evoked Potentials, Somatosensory Evoked Potentials, Spinal Evoked Potentials and Brainstem Auditory Evoked Potentials in Cavalier King Charles Spaniel Dogs with and Without Syringomyelia. K Wolfe, S Nykamp, DG Allen, J Armstrong, R Poma. J Vet Intern Med 2010;24:--- (ACVIM 28th Ann. Vet. Med. Forum Abstract Program: Abstract 231). Quote: "The aim of this study was to evaluate the validity of transcranial magnetic motor evoked potentials (TMMEP), somatosensory evoked potentials (SSEP), spinal evoked potentials (SEP) and brainstem auditory evoked responses (BAER) in the assessment of motor and sensory pathways throughout the central nervous system of CKCS dogs with and without SM diagnosed by MRI. Fifty CKCS dogs were evaluated. Neurologic deficits were graded 0–3 (0 5 normal, 1 5 cervical or thoracolumbar pain on palpation, 2 5 cervical or thoracolumbar pain on palpation plus evidence of neuropathic pain, 3 5 ataxia or paresis). TMMEP, SSEP, SEP, and BAER were performed on all dogs under sedation with hydromorphone (0.05 mg/kg IV) and acepromazine (0.025 mg/kg IV). Onset latencies (msec) were measured for TMMEP, SSEP and SEP and IV interpeak latencies were measured for BAER. Dogs were anesthetized for brain and spinal cord MRI (cervical, thoracolumbar, lumbar) including sagittal and transverse T2-weighted images. ... Based on neurologic score and MRI findings, all dogs were classified into group A (n 5 16) (neurologic abnormalities and MRI confirmed SM), B (n 5 9) (neurologic abnormalities and no SM), C (n 5 11) (normal neurologic examination and MRI-confirmed SM), and D (n 5 14) (normal neurologic examination and no SM). There were no significant differences observed in the mean latencies of TMMEP, SSEP, SEP and BAER between groups A, B, C and D. However, a significant linear correlation was observed between the severity of neurologic dysfunction and size of the syrinx (p 5 0.017; t-test procedure, SAS) with a larger syrinx being associated with more severe neurologic signs. In conclusion, TMMEP, SSEP, SEP and BAER do not appear to be valuable tests in detecting functional abnormalities of the motor and sensory pathways throughout the central nervous system of CKCS dogs with and without neurological signs secondary to SM diagnosed by MRI."

Association between Chiari-like malformation and syringomyelia in cavalier King Charles spaniels. C. J. Driver, C. Rusbridge, H. R. Cross, I. McGonnell, and H. A. Volk. Vet Rec., Aug. 2010 167:306.

Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Wiley-Blackwell Publ. 52.

Concurrent occipital hypoplasia, occipital dysplasia, syringohydromyelia, and hydrocephalus in a Yorkshire terrier. Laura Cagle. Can Vet J. 2010 Aug.; 51(8): 904–908.

The Incidence of Syringomyelia in the Cavalier King Charles Spaniel. J. E. Parker, S. P. Knowler, C. Rusbridge, T. J. McKinley, E. Noorman and N. D. Jeffery. Abstract at 23d ECVN symposium, Sept. 2010. Quote: "The epidemiology of cervical syringomyelia in a population of 804 Cavalier King Charles Spaniels (CKCS) was investigated using the results of a voluntary MRI screening programme that is ongoing in the United Kingdom (UK) and the Netherlands. The aim of the study was to establish the incidence of disease and to determine the risk factors for its development. ... The lifetime risk of developing syringomyelia in the study population was estimated to be 55%. Of the variables investigated, only the age at which a scan was performed significantly predicted the outcome of screening and the likelihood of detecting the disease increased with age-at-scan up to the age of four years. The predictive accuracy of the final model was 62.4% and factors not evaluated by this study are therefore also likely to contribute to the timing of disease manifestation. It is concluded that syringomyelia is likely to be one of the most common disease conditions of the CKCS. The age at which an MRI scan is performed predicts the likelihood of disease detection and a susceptible individual may not express the diagnostic phenotype until the age of four. Performing screening before this time may give a false negative result for the lifetime risk of disease development."

Interim Breeding Guidelines -- 4 Year Report. SP Knowler, AK McFadyen, C Rusbridge. Abstract at 23d ECVN symposium, Sept. 2010. Quote: "...a cohort of 465 dogs (307 females, 158 males) were identified which had either one (316 dogs) or both parents (149 dogs) with MRI confirmed CMSM status. Of these, 393 were CKCS [cavalier King Charles spaniels] and 72 were Griffon Bruxellois. All dogs were assigned an A - F CMSC grade according to the current breeding guidelines. Grade A implies a SM unaffected dog over 2.5 years old. In addition, to estimate the influence of late onset SM, an Grade A* was assigned to Grade A dogs over 5 years old. The CMSM grade of all offspring from all possible breeding combinations including using one parent of unknown status (Grade U) was ascertained. Offsrping without SM only occurred when there was at least one parent of Grade A status. There were higher numbers of SM clear offspring if both parents had A status. In addition all A* offspring also had at least one A* parent and higher numbers of A* offspring resulted from crosses where both parents were A*. There was no influence of gender on SM affectedness. All offspring were SM affected if both parents were SM affected. SM affected offspring may also occur when SM unaffected dogs are used (15.4% from A x A parent crosses and 7.7% from A* x A* parental crosses). Using dogs of unknown status was risky for SM affectedness. Fifty percent of older offspring were SM affected in A x U parental crosses and there were higher numbers of SM affected dogs with other parental combinations that included one Grade U dog. In conclusion, to increase the number of SM unaffected offspring, at least one parent should be ascertained to be free of SM by MRI at 2.5 years of age. Ideally both parents would be free of SM at 2.5 years of age and the true SM status of the grandparents at least 5 years old should be established. It is recommended that all breeding dogs from breeds susceptible to CMSM be MRI screened and results submitted to an officially recognised central database."

Brachycephalic Airway Obstructing Syndrome: Some Further Controversies. Robert N. White. Assn. of Veterinary Soft Tissue Surgeons. Oct. 2010. Quote: "The Cavalier King Charles spaniel also warrants further discussion. Previous reports from the UK and Australia would suggest that this breed in commonly presented for the investigation and management of BAOS (Lorinson and others 1997, Torrez and Hunt 2006) in both these countries. Surprisingly, a recent retrospective series of 62 dogs from North America (Riecks and others 2007) contained no individuals of the breed. Like the three breeds discussed above [Yorkshire terrier, the Norfolk terrier and the Norwich terrier], it is my experience that the Cavalier King Charles spaniel presented for the further investigation of ʻBAOSʼ commonly does not have the classic findings seen in the bulldog, French bulldog, Pekinese, Pug, etc. Their nasopharyngeal obstruction is often characterised by a subjectively narrow (smaller than expected for a breed of their size) nasopharyngeal space and it is quite common that they do not show evidence of overlength of the soft palate. Interestingly, a recent report (Hayes and others 2010) confirmed a significant association between the presence of otitis media with effusion (on MRI) and an increase thickness of the soft palate and reduced nasopharyngeal aperture. Many of the cases show evidence of otitis media with effusion (OME) on either otoscopic examination or other imaging studies of the tympanic bullae. Malformation of the nasopharynx and soft palate is recognised to be associated with the formation of otitis media with effusion in the dog (White and others 2009). The prevalence of caudal fossa (craniocervical junction abnormalities including occipital hypoplasia) malformations is high in the Cavalier King Charles spaniel and is considered to be associated with the presence of neurological signs observed in individuals suffering from cerebellar herniation and syringohydromyelia (Cerda-Gonzalez and others 2009). It would seem reasonable to hypothesise that the Cavalier King Charles spaniel might suffer from a syndrome of conditions (syringomyelia, OME, nasopharyngeal airway obstruction, etc.) that are all associated with the malformation of the caudal aspect of the skull."

Morphometric Assessment Of Cranial Volumes In Age-Controlled Cavalier King Charles Spaniels With And Without Syringomyelia. C. J. Driver, C. Rusbridge, I. M. McGonnell, H. A. Volk. Vet.Rec.; Dec 2010; 167:978-979. Quote: "Cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM) and syringomyelia have more brain parenchyma within the caudal cranial fossa (CCF) (CCFP), and also display ventriculomegaly, compared with CKCS with CM alone (Driver and others 2010). ... This short communication describes a retrospective, volumetric comparison of three variables (CCF, CCFP and ventricular dimensions) between CKCS with syringomyelia when less than two years of age and CKCS older than five years without syringomyelia. ... Dogs were grouped into those diagnosed with CM and syringomyelia when less than two years of age, and those with only CM aged five years or older when scanned. ... There was a significant difference in ventricular dimensions between the young dogs with syringomyelia ... and the unaffected older dogs ... Similarly, mean (sd) CCFP was significantly different between the groups.... Furthermore, the young CKCS with syringomyelia had a smaller mean ... than the unaffected older dogs  ... These results are consistent with previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia (Driver and others 2010). The present results suggest that the CCF volume is also significantly smaller in dogs with syringomyelia. ... The development of syringomyelia may be related to a cumulative effect of a small CCF and enlarged CCFP; however, as there is little difference between the measurements numerically, it is unknown how this would affect CKCS clinically and biologically. Further cohort and longitudinal studies are required to assess whether measuring the ventricular dimensions would be useful in differentiating CKCS that will develop syringomyelia from those that will not."

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2011

Distribution of syringomyelia along the entire spinal cord in clinically affected Cavalier King Charles Spaniels. Shenja Loderstedt, Livia Benigni, Kate Chandler, Jacqueline M. Cardwell, Clare Rusbridge, Christopher R. Lamb, and Holger A. Volk. Vet.J. 2011 187:---. Quote: "Chiari-like malformation (CM) and syringomyelia (SM) is an important disease complex in the Cavalier King Charles Spaniel (CKCS) but data about the anatomical distribution of SM along the spinal cord are lacking in veterinary medicine. The objective of this study was to define the anatomic distribution of SM in CKCS clinically affected by CM/SM. Magnetic resonance imaging (MRI) of the brain and the entire spinal cord of 49 dogs was performed and different morphological parameters compared. ... CM was present in all patients. ... All dogs in the present study were clinically affected. ... SM was absent in 25% of dogs with clinical signs. ... {I}maging only the cervical spine in clinically affected CKCSs is likely to underestimate the total syrinx size and the anatomical distribution of SM. The presence of cervical SM in all dogs with MRI evidence of SM could however justify the restricted imaging under screening purposes. ... In the majority of cases in our study, the syrinx borders were not well demarcated on T2-weighted MR images. Syrinx outlines were however distinctly visible in T1-weighted images. ... The results of our study showed syrinx formation in all regions of the spinal cord with no significant differences of [syrinx size] between the cervical, cervicothoracic and thoracolumbar regions, but significantly smaller syrinx in the caudolumbar spinal region. ... In our study Smax was most often seen within the C1–C4 region and, interestingly, also over T2–L2 vertebral bodies. ... Our data offer a description of the distribution and size of SM in clinically affected CKCS and challenge the current pathophysiological theories. ... We found that the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs. ... There is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region. Diagnostic imaging limited to the cervical spine in clinically affected CKCS is likely to underestimate the degree and severity of SM. It can be hypothesised that SM has a progressive nature in CKCS, which requires further characterisation."

Corticosteroid & Nonsteroidal Antiinflammatory Drug Interactions. Patricia Dowling. Clinician's Brief. March 2011;89-92.

Growth of Clinical Veterinary Magnetic Resonance Imaging. Patrick R. Gavin. Vet.Rad. & Ultra.; Mar/Apr 2011; 52(s1):52-54. "In the spine, MR imaging reveals conditions which were previously difficult to diagnose ante-mortem, and may facilitate study of their pathophysiology. Examples include syringohydromyelia associated with Chiari-like malformation in the Cavalier King Charles spaniel... ."

Correlating Magnetic Resonance Findings with Neuropathology and Clinical Signs in Dogs and Cats. Charles H. Vite, Johnny R. Cross. Vet.Rad. & Ultra. Mar/Apr 2011; 52(1),Supp. 1:S23–S31.

Evaluation of cerebrospinal fluid in Cavalier King Charles Spaniel dogs diagnosed with Chiari-like malformation with or without concurrent syringomyelia. Whittaker DE, English K, McGonnell IM, Volk HA. J Vet Diagn Invest. 2011 Mar;23(2):302-7. "Syringomyelia is a common clinical problem in the Cavalier King Charles Spaniel dog population. The underlying pathophysiology of the development and progression of syringes is currently unknown. The primary aim of the current study was to determine whether development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. Patient records of Cavalier King Charles Spaniels with Chiari-like malformations, with or without concurrent syringomyelia, that had magnetic resonance imaging and cerebrospinal fluid analysis between December 2004 and December 2009, were retrospectively reviewed. Total nucleated cell count per microliter, with differential count, red blood cell count per microliter, and protein concentration (g/l), were reviewed. Data were analyzed with the Mann-Whitney U-test. Spearman rank test was used to test association between cerebrospinal fluid composition and syrinx size, and the Fisher exact test was used to compare the presence of macrophages, reactive lymphocytes, and myelin. A P value of ≤0.05 was considered significant for statistical tests. Dogs with syringomyelia had a higher total nucleated cell count (syringomyelia: 4/µl [range, 0-15/µl] vs. without syringomyelia: 2/µl [0-8/µl]; P  =  0.0047), higher protein concentration (syringomyelia: 0.26 g/l [0.07-0.42 g/l] vs. without syringomyelia: 0.2 g/l [0.12-0.39 g/l]; P  =  0.039), and an increased neutrophil percentage (syringomyelia: 0% [0-37%] vs. without syringomyelia: 0% [0-21%]; P  =  0.0203) than those with the Chiari-like malformation alone. There was a positive correlation between total nucleated cell count and syrinx size (r  =  0.51; P  =  0.0068). Development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. The pathogenesis of syringomyelia has not been fully elucidated; therefore, the exact origin of cerebrospinal fluid changes remains unclear."

Syringomyelia in Cavalier spaniels treated successfully with palmitoylethanolamide (PEA). Jan M. Keppel Hesselink. Instituut voor Neuropathische Pijn. April 2011.  Quote: "In central neuropathic pain inflammatory and gial pathology might play a more important role than we previously thought. Recently in this field new drugtargets emerged and research into the treatment of central neuropathic pain is now slowly unfolding. One of those targets is the glia, and the phrase gliopathic pain has been used to point out the importance of the glia in neuropathic pain. The enodcannabinoid palmitoylethanolamide is a new analgesic compound within this new field. We conducted a pilot trial using palmitoylethanolamide in a animal model for central neuropathic pain, the cavalier KIng Charles spaniel, suffering from Arnold Chiari malformations and syringomyelia, and exposing classical pain behaviour. ... Central neuropathic pain is a prominent feature in 50 to 90% of adult human patients with syringomyelia. Recently, a direct relationship has been described between central neuropathic pain and objective markers of spinal cord damage. Large syrinxes leading to damage to the dorsal part of the spinal cord are leading to abnormal behaviour seen by cavalier King Charles spaniels. This behaviour is likely to be "neuropathic pain," and therefore it is suggested that conventional analgesic medication may be ineffective. ... In the Netherlands we conducted an open pilot trial and included 12 Cavalier king Charles spaniels, alle with MRI-scan positive syringomyelia and all suffering from behavioural abnormalities and objective signs related to syringomyelia and neuropathic pain. ... All dogs were weaned off their analgesic medication before entering the trial. During 2 months PEA was given in a dose of around 30 mg/kg BW. So most dogs received 150 mg twice daily. If dogs are very light (less then 6 kg) we start with PEA 200 mg. Dogs between 6-12 kg mostly get twice daily 150 mg and heavy dogs, and non responders twice daily 200 mg. As the substance isn tolerated very well, a bit more is no problem, up to 40 mg/kg dog. If dogs get too a higher dose, they start painting and they become restless. A composite scale scored by the dog owners was used, based on whether symptoms were the same, improved a bit or improved a lot. The first item was the overall general impression, the other items were linked to behavioural abnormalities, such as: cheery, lively (same, better, much better); headache (eyes closed) (same, better, much better); lacrimation (same, less, much less); chewing and swallowing, (same, less, much less); scratching, licking, rubbing (same, less, much less) ; moving around (same, better, much better). Results: After 2 months of PEA use in 12 Cavalier spaniels, the results were the following. Of all the 12 dogs, based on the overal general impression the owners could clearly detect improvement within 8 days, and in 5 dogs the improvement was seen already after 3-4 days. Within 4 weeks all dogs showed improvements. More specifically: General impresison: in 4 dogs better and in 8 dogs much better. ; cheery/ lively: same 0, better: 5 much better: 7; headache (eyes closed): same 0, better: 5, much better: 7; lacrimation: same: 3, less: 3 much less: 6; chewing and swallowing, same: 3, less: 3 much less: 5 (1 not scored); scratching, licking, rubbing: same: 2, less: 5 much less: 5; moving around: same: 2, better: 2 much better: 7 (1 not scored) Qualitative statements of owners One owner states she can pat the dog again, and the dog played again with younger dogs. Some owner stated that the dog’s skull was less hot. One owner of a dog suffering from chronic ear inflammation (PSOM) could tough the dogs head and ears again. In one dog the owner stated that the lordosis vanished, one other dog showed affective behaviour and touching was again possible, etc, etc. All dog owners noticed impressive positive changes in behaviour after treatment with PEA. Follow-up: meanwhile many dogs are treated for many months, and most dogs are still very much stable. The first signs of efficacy is less inflammation of the eyes, and less lacrimation, already sometimes after some days. As syringomyelia is a spinal cord condition, is it important to point out that palmitoylethanolamide has been evaluated in other models of spinal cord injury too. And these models supported its therapeutic role. Palmitoylethanolamide is the naturally occurring amide of palmitic acid and ethanolamine. In a great number of pharmacological trials this molecule has been shown to reduces pain and inflammation through the nuclear receptor PPAR-alpha. This receptor is activated by PEA. PEA can reduce secondary damage induced by experimental spinal cord injury (SCI) in a mice model. SCI leads to edema, neutrophil infiltration, and production of inflammatory mediators, tissue damage, and apoptosis. Repeated PEA administration significantly reduced: •1) the degree of spinal cord inflammation and tissue injury; •2) neutrophil infiltration; •3) nitrotyrosine formation; •4) proinflammatory cytokine expression; •5) nuclear transcription factor activation-kappaB activation; •6) inducible nitric-oxide synthase expression; and •6) apoptosis. Hand in hand with these biochemical improvements, PEA ameliorated the recovery of motor limb function. In a compression model induced by applying an aneurysm clip to the spinal cord in mice repeated PEA administration (10mg/kg i.p., 6 and 12h after SCI) significantly reduced the degree of the severity of spinal cord trauma through the reduction of mast cell infiltration and activation. PEA also significantly reduced the activation of microglia and astrocytes expressing cannabinoid CB(2) receptor after SCI. PEA also acted as a neuroprotectant via induction of neurotrophic factors. The results of this pilot trial are in line with experimental findings supporting the neuroprotective role of PEA, as well as its role as a anti-inflammatory and analgesic compound. The avaiibility of Normast [Peapure] for human and dog sufferers of central neuropathic pain is a leap forward in the treatment of this difficult to treat pain state."

Effects of syringomyelia on electrodiagnostic test results in Cavalier King Charles Spaniels. Thomas R. Harcourt-Brown, Zoe Belshaw, John E. Parker, Nick D. Jeffery,  Nicolas Granger. Am J Vet Res, May 2011;72(5):595-600. Quote: "Objective — To determine the effects of syringomyelia on electromyography (EMG) findings, somatosensory-evoked potentials (SEPs), and transcranial magnetic motor-evoked potentials (TMMEPs) in Cavalier King Charles Spaniels (CKCSs). Animals — 27 client-owned CKCSs that underwent prebreeding magnetic resonance imaging screening or investigation of clinical signs consistent with syringomyelia. Procedures — In dogs with (n = 11) and without (16) magnetic resonance imaging-confirmed syringomyelia, the median nerve in each thoracic limb was stimulated and SEPs were recorded over the C1 vertebra; onset latency and latency and amplitude of the largest negative (N1) and positive (P1) peaks were measured. The TMMEPs were recorded bilaterally from the extensor carpi radialis and tibialis cranialis muscles; onset latencies in all 4 limbs were measured. Bilateral systematic needle EMG examination was performed on the cervical epaxial musculature, and the number of sites with spontaneous activity was recorded. Results — In dogs with syringomyelia, amplitudes of N1 and P1 and the amplitude difference between P1 and N1 were significantly smaller than those recorded for dogs without syringomyelia (approx 2-fold difference). No difference in SEP latencies, TMMEP latencies, or the proportion of dogs with > 2 sites of spontaneous activity detected during EMG examination was detected between groups. Conclusions and Clinical Relevance — Results indicated that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease."

Whole Genome Study Identifies a Candidate Region for Chiari-like Malformation in Brussels Griffon.   LeMay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z. Sainte-Justine University Hospital Center Research Center 18 June 2011. Quote: “Chiari malformation type 1 (MCI) ... in humans is similar to a disease in dogs called Chiari-like malformation (CM). This disease has a particularly high incidence in the Brussels Griffon breed (GB). ... Results: Analysis of type case / control genotypes generated by the study of whole-genome association identified six genomic regions with significant scores. ...[A] genomic region on chromosome 2 was significantly associated with MC (P = 1.9x10-5 when corrected EIGENSOFT). Haploview identified a haplotype block extending over a region of 2.9 Mb which is significantly associated with CM with a P value of 6.87 x10-10. The fine mapping has identified three new SNPs significantly associated with CM with P values of 1.938x 10-6, 1.61x 10-5, 5.36x 10-6 in addition to allowing a reduction in haplotype 1.7 Mb.  Conclusion: A region of a 1.7 Mb on chromosome 2 is associated with CM in the GB. To reduce this region, other breeds genetically related to GB and affected by CM will be genotyped to identify a region shared by CM affected. In addition, a case / control over a larger cohort will increase the resolution of this region."

Prevalence of asymptomatic syringomyelia in Cavalier King Charles spaniels. J. E. Parker, S. P. Knowler, C. Rusbridge, E. Noorman, N. D. Jeffery. Vet.J. June 2011;168(25):667. Quote: "The prevalence of syringomyelia was investigated in a sample population of 555 Cavalier King Charles spaniels. All dogs, which were declared by their owners to be showing no clinical signs of syringomyelia, underwent MRI to determine the presence or absence of the condition. Data were analysed by logistic regression to determine the effects of sex and age on the prevalence of syringomyelia. Only increased age was found to have a significant effect. The prevalence of syringomyelia was 25 per cent in dogs aged 12 months, increasing to a peak of 70 per cent in dogs aged 72 months or more. ... The evidence for a lower prevalence in younger animals is more reliable (because of the higher numbers included in the present study and the lower likelihood of false inclusion) and this effect lasts until dogs are at least three years of age. This finding has important implications for the design of a screening test procedure and may conflict with the current recommendations that the optimum age for screening should be 30 months. These data would imply that it is probable that dogs aged up to three years may yet have reduced odds for the diagnosis of syringomyelia. However, there is a need for the dogs to be screened when they are reasonably young so that breeders can decide at an early stage whether their animals are suitable for breeding; many breeders would consider 36 months unduly old.... The high lifetime prevalence of syringomyelia raises concerns for the welfare of the CKCS breed and also suggests that eliminating the genetic risk factors for the disease by selective breeding may be difficult, because the heritability has previously been shown to be complex, and the prevalence of the determinant genes within the population is therefore likely to be high. The true prevalence of syringomyelia in the general CKCS population is expected to be higher than that found in this sample population because symptomatic dogs were specifically excluded."

Preliminary Morphometric Evaluation of Syringomyelia in American Brussels Griffon Dogs. A.C. Freeman, S.R. Platt, M. Kent, E. Huguet. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-3). Quote: "The aims of this study were to investigate the ABG for (i) the prevalence of skull abnormalities; (ii) the prevalence of SM; (iii) an association between lateral ventricular size, cerebellar size and SM; and (iv) associations between SM, skull abnormalities, CSF pleocytosis and clinical signs. Seventy-six ABGs, recruited as part of a larger epidemiological and genetic study, underwent brain and spinal MRI evaluation ... . All dogs were evaluated neurologically, recording deficits and the presence of spinal pain. ... . Forty-five dogs underwent atlanto-occipital cerebrospinal fluid tap at the time of MRI and the white blood cell (WBC) count was recorded. ... The mean age of the 30 males (24 intact) and the 46 females (34 intact) was 50.4 months (range 8–135; median 44 months). Neurological deficits and neck pain were noted in 21 (27%) and 15 (19.7%) of dogs respectively; 5 dogs (6.57%) exhibited both. Cerebellar deviation and vermal herniation were present in 37 (48.68%) and 46 (60.52%) dogs respectively; twenty-three dogs (30.26%) had both. Mean height of the CC was 2.3mm (0–7.2 mm). Forty (52.63%) Ccs were greater than 2mm in height; the mean length of these lesions was 2.03 vertebrae (0.5–7). Mean CSF WBC count was 4.97/µl (0– 39). Syrinx height and extent were significantly higher in dogs with neurological signs (size p = 0.01; extent p 5= 0.0004). There were no significant differences in syrinx sizes and extent in dogs with or without skull abnormalities or spinal pain. There were no associations of syrinx height or extent with CSF WBC count or age of dog. Intact females had a significantly lower syrinx extent than intact males (p = 0.009). There were no significant differences in presence of spinal pain or neurological signs between dogs with or without skull abnormalities. There was a significant negative association of ventricular percentage and cerebellar percentage (p < 0.0001). There was a significant association of ventricular percentage with syrinx percentage (p = 0.0015) and height (p = 0.0007). This study suggests that SM and CM are prevalent in ABGs. Syrinx size and extent are associated with neurological signs and ventriculomegaly is associated with both small cerebellar size and large syrinx size. However, SM may not be associated with CM as defined by cerebellar herniation and deviation and is not associated with CSF inflammation."

Chiari-like Malformation, Syringomyelia and Neuropathic Pain: Cerebrospinal Fluid Neurotransmitter and Cytokine Levels. S.R. Platt, A.C. Freeman, M. Kent, E. Huguet, G. Edwards, R. Barber. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 93B). Quote: "The pathogenesis of neuropathic pain (NP) and syringomyelia (SM) in association with Chiari-like malformation (CLM) in dogs has focused on the anatomical anomalies and secondary cerebrospinal fluid (CSF) flow abnormalities. Neuropathic pain in humans has been associated with abnormalities of neurotransmitters such as glutamate and serotonin as well as immunologic mechanisms. The aim of this study was to investigate the CSF neurotransmitter and cytokine levels in Brussels Griffon dogs (BGs) with CLM, SM and NP.

Relationship of Cerebellar Volume to Syringomyelia in the Cavalier King Charles Spaniel. TA Shaw, I McGonnell, CJ Driver, C Rusbridge, HA Volk. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-12). Quote: "The objective of this study was to assess the role of cerebellar volume in caudal cranial fossa overcrowding and syringomyelia. ... Forty-five small breed dogs (SB), 58 CKCS and 31 Labradors (LD) were compared. As SM is thought to be a late onset disease process, two subgroups were formed for comparison: 21 CKCS younger than 2 years with SM (group 1) and 13 CKCS older than 5 years without SM (group 2). CKCS had a larger cerebellar caudal cranial fossa percentage than the other groups (CKCS 52.19% [40.07–58.76%] vs. SB 47.81% [40.36–62.91%] and LD 41.32% [32.59–52.95%]; p o 0.001). The cerebellar brain percentage was also larger in CKCS compared to the other groups (CKCS 8.90% [6.62–11.46%] vs. SB 7.37% [5.25– 11.34%] and LD 7.23% [6.36–9.54%]; p o 0.001). Group 1 had a significantly larger cerebellar caudal cranial fossa percentage than group 2 (53.71% 1.27 vs. 49.31% 2.35, p 5 0.001) and a significantly larger cerebellar brain percentage (9.45% 0.43 vs. 8.58% 0.55, p 5 0.021). Our findings show that the CKCS has a relatively larger cerebellum than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS." es were analysed for presence of serotonin (ng/ml), glutamate, glycine and GABA (mg/ml) by high performance liquid chromatography. ... All hypothesis tests were 2-sided and the significance level was á = 0.05. NP was detected in 8 dogs (17%); SM was present 24 dogs (52%); and CM was detected in 24 dogs (52%). IFN-g levels were significantly lower in dogs with NP than without (p = 0.036). There were significant positive correlations between syrinx size and IL-8 (p = 0.017),KC(p = 0.025) and MCP-1 (p = 0.003). There were significant negative correlations between IFN-g and syrinx height (p = 0.025) and extent (p = 0.042). There was a significant negative correlation between IL-2 and syrinx height (p = 0.042). Neurotransmitter levels were not associated with skull abnormalities or spinal pain, but there was a positive correlation of glycine with IL-2 (p = 0.004) and MCP-1 with glutamate (p = 0.0147) and serotonin (p = 0.0059). The size of the syrinx in BGs with SM is associated with several cytokine elevations but only a decrease of IFN-g was associated with NP. Based on this study it does not appear that excitotoxicity plays a role in either SM development or NP. Further work is justified on the role of the immune system in CM, SM and NP."

Effect of Omeprazole on Serum Gastrin Concentrations and Calcium Metabolism in Healthy Dogs. O. Dossin, K. Jones, M. Ridgway, S. Clark-Price, JM. Steiner, JS. Suchodolski. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract GI-5). Quote: "Proton pump inhibitors (PPI) are widely used in human and also veterinary medicine. Side-effects of PPI treatment reported in people are atrophic gastritis, gastric and esophageal cancer, and rebound hyperacidity following cessation of treatment, which has been speculated to be due to a sustained increased in circulating gastrin concentration. Moreover, long-term PPI treatment has been associated with an increased risk for osteoporosis in people. Little is known about the effect of PPI treatment on serum gastrin concentration or calcium metabolism in dogs. Eight healthy adult research dogs (4 males and 4 females) were enrolled into the study. The dogs received an average dose of 1.1 mg/kg of omeprazole orally twice daily for 15 days. ... This study shows that treatment with omeprazole for 2 weeks results in a profound and sustained increase in serum gastrin concentration in dogs. This effect is rapidly reversible after cessation of the treatment. No effect on calcium metabolism was observed. However, this study documents only the effect of short-term treatment and it is possible that the effects of long-term administration are different."

Changes over Time in Caudal Cranial Fossa Volumes and of Cerebellar Herniation in Cavalier King Charles Spaniels with Chiari-like Malformation. S. Hamilton, L. De Risio, C. Rusbridge, CJ Driver, R. Dennis, I McGonnell, HA Volk. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-13). Quote: "There is currently a lack of information if the morphological changes seen in CKCS with CM are progressive or non-progressive. In this retrospective study we used established measurements of cerebral volumes, foramen magnum height and cerebellar herniation length to assess if there is a significant difference between subsequent magnetic resonance (MR) imaging of the brain of the same dog. Electronic patient records were reviewed for CKCS with CM which had two separate MRI scans, which were a minimum of 3 months apart. CKCS with diseases affecting measurements were excluded. ... Volumes of the caudal cranial fossa parenchyma were analyzed as percentages of caudal cranial fossa volume and caudal cranial fossa volume was analyzed as a percentage of total cranial cavity volume. The volume of the ventricular system was recorded as a percentage of total parenchymal volume. Data was assessed for normality and the appropriate statistical test was used to compare means/medians. Twelve CKCS were included with a median scan interval of 9.5 months (3–83 months). The size of the foramen magnum increased significantly between the first and second scan ..., as did the length of cerebellar herniation ... There was no significant difference noted between the two time points in any of the other volumetric measurements ... This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."

Morphometric Features of the Craniocervical Junction Region in Dogs with Suspected Chiari-like Malformation: 274 Cases (2007–2010). Dominic J. Marino. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 95A). Quote: "Concurrent malformations of the cranio-cervical junction are commonly identified in humans with Chiari type I malformation. Recent evidence suggests such craniocervical junction abnormalities (CJAs) also occur in dogs suspected of having Chiari-like malformation (CLM). The purpose of this study was to objectively describe morphometric features of the craniocervical junction region of dogs with suspected CLM and to investigate for associations between these features and the occurrence of other malformations in this region. Magnetic resonance (MR) and computed tomographic (CT) images from 274 dogs with CLM were evaluated. Three regions of neural tissue compression were assessed: cerebellar compression (CC); ventral compression at the C1/C2 articulation, termed ‘‘medullary kinking’’ (MK); and dorsal compression (DC) at the C1/C2 articulation. A compression index (CI) was calculated for all abnormal regions for each dog. Multiple logistic regression analysis was performed (p o 0.05) to ascertain whether CI values for the different regions of compression were associated with the incidence of other cranio-cervical junction abnormalities. 68% of dogs had MK and 38% of dogs had DC. 28% of dogs also had evidence of atlanto-occipital overlapping (AOO). Breed and severity of CC were the only significant predictors of AOO (p o 0.0001 and po0.0092). 28% of suspected CLM cases have AOO as the anatomic abnormality responsible for CC. Compression index values may help differentiated subtypes of CJAs in dogs."

Medical Infrared Imaging (Thermography) of Type I Thoracolumbar Disk Disease in Chondrodystrophic Dogs. CA Loughin, DJ Marino. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 95B). Quote: "Medical infrared imaging (MII) is a non-invasive diagnostic imaging technique that measures skin surface temperature and generates thermal pattern maps based on predetermined color scales. Because skin temperature, dependent on regional perfusion, is under direct control of the sympathetic nervous system, MII provides information about the function of the autonomic nervous system. Because of recent advances in technology and lack of sedation needed to image patients, MII has potential use as a screening test for a variety of conditions that may result in autonomic dysregulation like Chiari-like malformation in dogs (CLM). The purposes of this study were to establish a MII protocol for dogs suspected of having CLM, to identify thermal imaging patterns for various regions of interest (ROI), to evaluate changes in thermal patterns and compare the results to those of MRI findings, considered the standard for diagnosing CLM in dogs. One hundred and five Cavalier King Charles Spaniel dogs with clinical signs attributable to CLM and confirmed CLM with MRI were evaluated with a complete blood count and chemistry profile, examination by a board certified surgeon/neurologist, mult-idetector CT scan of the cranio-cervical junction, whole body MRI and MII. The protocol for thermal imaging included cranial and caudal views of the body, full lateral right and left body views, dorsal views of the head and body, and right and left lateral views of the head. Thermal patterns were assessed with custom image recognition software. After each dog was imaged awake, general anesthesia was administered and the dogs re-imaged using the same protocol. MRI findings in dogs with severe or moderate cerebellar compression and cerebellar herniation were compared with MII results. The top of head and front of head ROI were 89.2% and 97.3% successful in identifying dogs with CLM. Based on these preliminary findings, MII may be a viable screening tool to detect CLM in dogs."

Cephalometric Measurements and Determination of General Skull Type of Cavalier King Charles Spaniels M. J. Schmidt, A. C. Neumann, K. H. Amort, K. Failing, M. Kramer. Vet. Rad. & Ultra, 26; Jul/Aug 2011;52(4):436-440. Quote: "The general skull morphology of the head of the Cavalier King Charles Spaniel (CKCS) was examined and compared with cephalometric indices of brachycephalic, mesaticephalic, and dolichocephalic heads. Measurements were taken from computed tomography images. Defined landmarks for linear measurements of were identified using three-dimensional (3D) models. The calculated parameters of the CKCS were different from all parameters of mesaticephalic dogs but were the same as parameters from brachycephalic dogs. However, the CKCS had a wider braincase in relation to length than in other brachycephalic breeds. Studies of the etiology of the chiari-like malformation in the CKCS should therefore focus on brachycephalic control groups. As Chari-like malformation has only been reported in brachycephalic breeds, its etiology could be associated with a higher grade of brachycephaly, meaning a shorter longitudinal extension of the skull. This has been suggested for other breeds."

Understanding Chiari-like malformation: where are we now?  Rita Gonçalves. Vet Rec Sept 2011;169:275-276. Quote: "Over recent years, numerous studies have been done to try to enhance our understanding of CM in the CKCS. Several studies used morphometric measurement methods to quantify the size of the different components of the caudal cranial fossa (CCF) and quantify the degree of mismatch between them and the CCF. Initial studies suggested that CKCS with CM/ syringo-myelia have a smaller relative caudal fossa area, compared with control dogs such as labradors (Carrera and others 2009). However, subsequent studies failed to find the same association when comparing the caudal fossa of CKCS with and without syringomyelia using three-dimensional measurement methods (Cerda-Gonzalez and others 2009, Schmidt and others 2009, Driver and others 2010a). CKCS have also been shown to have proportionally the same volume of parenchyma within the CCF as labradors (Cross and others 2009). A more recent study considered the fact that signs of syringomyelia often only shows at an older age. In this study, CKCS with CM older than five years of age (controls) were compared with CKCS with CM/syringomyelia aged two years or less. This revealed a significantly smaller CCF in CKCS with CM/syringomyelia (Driver and others 2010b). Recently it was also shown that a more marked overcrowding of the CCF due to an increased brain parenchyma volume is associated with syringomyelia (Driver and others 2010a, 2010b). A combined evaluation of these findings suggests that a combination of a reduced CCF and an increase in the parenchyma contained within the CCF most likely contribute to the pathogenesis of this complex condition. ... It is common to detect CM in dogs presenting for other problems, and a study recently published in Veterinary Record showed that the prevalence of syringomyelia in dogs considered asymptomatic by their owners was 25 per cent in dogs aged one year and 70 per cent in those aged six years or more (Parker and others 2011). This discrepancy between the imaging findings and the clinical signs poses a major difficulty when designing studies aimed at improving our knowledge about this condition. These results also have important implications in the design of a screening test procedure, which was previously recommended for dogs aged two to three years, and suggests that eliminating the disease by selective breeding may be virtually impossible. ... In a paper summarised in this issue of Veterinary Record, Upchurch and others (2011) aimed to investigate the effect of positioning of the dog’s head during MRI on the severity of CM, ... Chiari-like malformation has for a decade now been widely identified in the CKCS population but despite its high prevalence, little is still known about its pathogenesis. Further studies are necessary to increase our understanding of this condition in order to allow the development of new treatment options and improve the welfare of the CKCS affected."

Influence of head positioning on the assessment of Chiari-like malformation in Cavalier King Charles spaniels. J. J. Upchurch, I. M. McGonnell, C. J. Driver, L. Butler, H. A. Volk. Vet Rec Aug 2011; 169(11):277. Quote: "Chiari-like malformation (CM) is almost omnipresent in the Cavalier King Charles spaniels (CKCS), often leading to syringomyelia (SM). Morphometric studies have produced variable results concerning relationship between the brain parenchyma within the caudal cranial fossa (CCF) and SM. The present study assesses the effect of head position, one potential confounder. Magnetic resonance images of CKCS with CM were reviewed in extended and flexed head positions. ... Fourteen CKCS were included into the study, seven dogs with CM and seven with CM/SM. ... The degree of cerebellar herniation was significantly worse in dogs with a flexed compared to an extended head position. ... Cerebellar herniation did not differ significantly between CKCS with and without SM in the extended head position. However, in the flexed head position the cerebellum herniated more caudally in CKCS with CM/SM compared to CKCS with CM alone. This highlights that the non-flexed head position may underestimate the true extent of cerebellar herniation and could explain why previous studies have missed an association with SM. ... It is well documented that flexing the head opens the CSF space of the cisterna magna and this could explain the morphometric measurements. The brainstem reduces in size to accommodate this increase in CSF space. ... When CSF space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. ... The reduced CSF space in CM/SM dogs reported in this study could explain this jet like CSF flow in dogs with CM/SM compared to those with CM alone. ... Furthermore, there is an association between head position and level of foramen magnum overcrowding. Based on these findings it may be appropriate to position patients in a more flexed head position for optimal imaging in order to identify morphologic changes more accurately. This is important to consider for imaging CKCS with CM especially when studying the pathogenesis of CM/SM. It should also be considered when taking a cisternal CSF sample as the spinal needle might be traumatic to the herniated cerebellum."

Histopathological Investigation of Syringomyelia in the Cavalier King Charles Spaniel. H.Z. Hu, C. Rusbridge, F. Constantino-Casas, N. Jeffery. J Comp Path. Sept. 2011. Quote: "Syringomyelia (SM) in Cavalier King Charles spaniels (CKCSs) is identified commonly on magnetic resonance images and is sometimes associated with clinical signs of pain and cervical hyperaesthesia. However, the mechanism by which SM develops in this breed has not been fully elucidated and the associated effects on spinal cord structure have not been reported previously. The aims of this study were to describe changes found in the spinal cord of CKCSs, to compare findings between symptomatic and asymptomatic dogs and to determine whether syrinx formation was associated with tissue destruction. Anomalies of the central canal were found in all specimens and many dogs had grossly visible fluid-filled cavities within the spinal cord. Prominent microscopical findings were spongy degenerative changes associated with neuronal necrosis and Wallerian degeneration. The ependyma was discontinuous in many specimens, notably in symptomatic individuals, and there was evidence of angiogenesis and fibrous tissue proliferation around blood vessels adjacent to syrinx cavities. Compared with two different samples of the normal dog population, dogs with syrinxes had significantly less grey matter, although this decrease was associated with generalized loss of spinal cord area. Therefore, SM is associated with degenerative changes in the spinal cord and may develop through primary disruption of ependymal integrity followed by vascular hypertrophy and proliferation. Glial and fibrous proliferation appears to be associated with expression of clinical signs. ... The pathology suggested that the primary development of syringomyelia is associated with central canal dilatation and damage which is accompanied by blood vessel changes. This is an important finding because there is so much debate on how syringomyelia develops in all species."

Distribution of substance P and calcitonin gene-related peptide in the spinal cord of Cavalier King Charles Spaniels affected by symptomatic syringomyelia. Hilary Zhaoxu Hu, Clare Rusbridge, Fernando Constantino-Casas, Nick Jeffery. Research in Vet Sci; Aug 2012; 93(1):318-320. Quote: "The causes of clinical signs associated with syringomyelia in the Cavalier King Charles Spaniel (CKCS) are incompletely understood. In this study we compared expression of two pain-related neuropeptides: substance P (SP) and calcitonin gene related peptide (CGRP), in the spinal cord dorsal horn of normal dogs with that in CKCS with and without clinical signs of syringomyelia. There was a decrease in expression of both peptides in CKCS with ‘symptomatic’ syringomyelia that was also associated with significant asymmetry in SP-I and similar, though non-significant, asymmetry in CGRP-I compared with other groups. ... This current study provides evidence to suggest that the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected."

Effectiveness of breeding guidelines for reducing the prevalence of syringomyelia. S. P. Knowler, A. K. McFadyen, C. Rusbridge. Vet Rec Oct 2011; doi:10.1136/vr.100062; Vet Rec Dec 2011;169:679-680. Quote: "Several toy breed dogs are predisposed to syringomyelia (SM), a spinal cord disorder, characterised by fluid-filled cavitation. SM is a complex trait with a moderately high heritability. Selective breeding against SM is confounded by its complex inheritance, its late onset nature and high prevalence in some breeds. This study investigated the early outcome of existing SM breeding guidelines. Six hundred and forty-three dogs, 550 Cavalier King Charles spaniels (CKCS) and 93 Griffon Bruxellois (GB), were identified as having either one (454 dogs) or both parents (189 dogs) with MRI-determined SM status. Offspring without SM were more common when the parents were both clear of SM (SM-free; CKCS 70 per cent, GB 73 per cent). Conversely, offspring with SM were more likely when both parents had SM (SM-affected; CKCS 92 per cent, GB 100 per cent). A mating of one SM-free parent with an SM-affected parent was risky for SM affectedness with 77 per cent of CKCS and 46 per cent of GB offspring being SM-affected. ... This paper serves to report the early outcome of using the 2006 breeding guidelines for dogs contributing to a genome project and whose pedigrees were known. The study suggested that SM-free offspring were more likely if both parents were SM-free and SM-affected offspring were more likely if both parents had SM. There was a trend that older SM-free dogs (*A) only resulted when at least one parent was *A. This finding seems logical but since *A and A grade dogs are in a minority it is problematic for breeders to select SM-free dogs especially when the SM status of the dog can alter with age.  Often, the true SM status may not be known until after the dog is used for breeding. In 2010, there were 2136 CKCS litters registered with the UK kennel club (8095 puppies). Of these, 33 per cent had a sire aged younger than 2.5 years on the day of mating and 36 per cent had a dam younger than 2.5 years on the day of mating. This translates as 55 per cent of the KC registered CKCS puppies having one parent younger than 2.5 years and 14 per cent having both (Grahame Ford, personal communication). Thus, a recommendation that only A or *A grade parents be used is unlikely to be practical for breeders. If a younger SM-free dog (C grade) is mated with an older dog (A grade), then there is greater risk for SM than with two A grade parents. The data in the study (Tables 3 and 4) suggested that 63 per cent (12/19) of offspring were SM-free from A or*AxC parents. This is likely to be an overestimation of the proportion of SM-free dogs since these figures include C grade offspring, which may develop SM as they become older. However, it could be argued that a recommendation to include at least one A grade dog in any proposed mating is a reasonable, practical alternative since it allows breeders to use their younger dogs. However, a far better proposal for prevention of SM and maintaining genetic diversity is a proposed mate select programme using estimated breeding values (EBV). ... The most controversial part of the 2006 breeding recommendations was that it permitted older clinically asymptomatic SM-affected dogs to be bred to older SM-free dogs. This was because there were only a few A grade dogs identified when the breeding guidelines were first proposed and overuse of these might limit genetic diversity, reducing the effective population size. This investigation showed that a proportion of the offspring from such a cross can be SM-free, however, in the CKCS, the number of SM-affected dogs was far greater than SM-free dogs (77 per cent SM-affected). Moreover, where these offspring had siblings, the ratio of SM-free to SM-affected was 1:1 compared with 3.5:1 for *A or Ax*A or A parents or 1:1.7 for D or ExU parents (Knowler and Rusbridge, unpublished data). It is debatable whether it is ethical to knowingly breed a dog with an inherited disease especially when the majority of the offspring may be destined for the pet-owning public, and this study suggested that it is not advisable to use SM-affected dogs for breeding. However, if the prevalence of SM is as high as 70 per cent in the CKCS (Parker and others 2011), this will have dire consequences for the effective population size of the breed. Again it is hoped that using an EBV mate select programme may allow safer parental crosses, maintaining genetic diversity while decreasing the number of SM-affected offspring. One problem noted with the 2006 breeding guidelines was that if the dog was deemed asymptomatic but SM-affected when first scanned over 2.5 years old it was attributed a grade D status. However, in some cases it was suspected, due to the size of the syrinx, that if the dog had been scanned when younger then the syrinx would have been apparent, in other words, the dog was actually an E grade. It was also possible that some dogs may have been clinically affected (ie, an F grade) as the early behavioural signs of pain from SM and/or CM can be subtle and/or intermittent and may not be detected in a routine clinical examination.  In addition, some breeders fail to recognise or acknowledge clinical signs of SM and/or CM. Since the aim of the guidelines is to reduce the incidence of early onset and clinical SM, a future recommendation is that a D status (or equivalent) will only be appropriate if the dog was first proved by MRI to be SM-free before 2.5 years of age. One encouraging observation was that the proportion of grade E (SM-affected younger than 2.5 years of age) dropped from an average of 15 dogs per year in years 2004 to 2006 to 11 dogs per year in years 2007 to 2009, that is, the breeding guidelines may be achieving the goal of reducing the risk of early onset SM, however, this hypothesis would be needed to be tested in a more vigorous study. ... In conclusion, the results from this study suggest that it is appropriate to continue using the breeding guidelines for both the CKCS and GB until a more robust system based on EBV or genetic testing is available. The following modifications are suggested but it should be realised that these are the recommendations that are based on limited data and consequently should be subjected to further prospective vigorous study: To increase the number of SM-free offspring, at least one parent should be ascertained to be SM-free by MRI as a young adult. In ideal circumstances, both parents would be SM-free. According to the study by Parker and others (2011), the optimum age for this early MRI screening is 36 months. If an SM-affected dog is used, for example, to preserve desirable traits or to increase genetic diversity then ideally the chosen mate would either be selected on the basis of its EBV and/or would be an older SM-free dog (five years or older). The offspring of the proposed mating should also be MRI scanned and ideally bred to older SM-free dogs. The SM status of the dog when at least five years old should be established. SM has a complex inheritance and an EBV mate select programme should allow breeders to select safer breeding combinations. To ensure success, the programme requires a substantial collection of accurate populationwide data. Consequently, all breeding dogs from breeds susceptible to CM and SM should be MRI screened and these results should be submitted to a central source. Pedigree and clinical history from dogs presenting with clinical signs of CM and/or SM should also be submitted to this central system. ‘D’ status (or equivalent) will only be appropriate if the dog was first proved to be SM-free before 36 months of age. Future breeding recommendations should also take account of dogs with CCD less than 2 mm. ..."

Dorsolateral spinal cord compression at the C2-C3 junction in two Cavalier King Charles spaniels. K. P. Harris,  T. C. Saveraid, and S. Rodenas. Vet Rec Oct 2011;169(16):416. Quote: "Due to the high incidence of Chiari-like malformation (CM) and syringomyelia (SM) in Cavalier King Charles spaniels (CKCS), the presentation of this breed with a history of apparent neck pain often prompts an early suspicion for CM-SM. Conversely, CM-SM findings upon MRI have been reported in many asymptomatic CKCS and thus other differentials for neck pain such as vertebral trauma, meningioencephalomyelitis or myelocompression must be exhaustively excluded. Cervical spondylomyelopathy (CSM), also referred to as cervical vertebral malformation-malarticulation syndrome, cervical vertebral stenotic myelopathy and wobbler syndrome among other terms, is a common multifactorial neurological disorder affecting mainly large/giant breed dogs. Cases of CSM have been broadly classified by their mechanism of spinal cord and/or nerve root compression as either disc-associated (DA-CSM) or osseous-associated (OA-CSM). This short communication describes dorsolateral compressive lesions of the spinal cord at the C2-C3 junction, similar to those described in giant breed dogs with OA-CSM, in two CKCS with concurrent CM, being evaluated with MRI for neck pain. To the author's knowledge, this is the first report of such MRI findings in this breed. In case 1, a 13.9 kg two-year-old male neutered CKCS presented with a three-month history of intermittent periods of apparent discomfort manifested as very abrupt rising from rest. Two weeks earlier, the owner had observed an isolated episode of ataxia during which the dog fell to the left, had a left-sided head tilt and facial twitching. The dog remained responsive to the owner throughout and returned to normal within 30 minutes. The owner also reported that the dog frequently scratched at one ear (the side unknown). Neurological and otoscopic examination revealed no abnormalities. Moderate to severe hyperaesthesia was evident upon manipulation of the cervical spine."

Use of the loop diuretic torsemide in three dogs with advanced heart failure. Mark A. Oyama, Gordon D. Peddle , Caryn A. Reynolds, and Gretchen E. Singletary. J Vet Cardio; Oct 2011; doi:10.1016/j.jvc.2011.10.001. Quote: "Diuretics are a mainstay of therapy in dogs with heart failure. In dogs with advanced heart failure, moderate to high doses of loop diuretics such as furosemide are used with diminishing effects as profound activation of neuroendocrine systems promote signs of congestive heart failure. The loop diuretic torsemide has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects. ... This case series describes 3 dogs [including a 12 year-old cavalier King Charles spaniel] with advanced heart disease that despite treatment with multiple cardiac medications and moderate to high doses of furosemide experienced frequently recurring episodes of CHF. ... In each dog, replacement of furosemide with a torsemide dose, in terms of mg/kg, at one-tenth to one-thirteenth of the daily furosemide dose were associated with apparent resolution of CHF for relatively long durations of time. We speculate that when switching to torsemide, restoration of diuretic response was the most likely cause of this observation. In these and other cases managed by the authors, pet owners report notable increases in their dog’s diuresis and water consumption following institution of torsemide. In a small prospective blinded cross-over study,13 dogs with heart failure experienced significantly higher serum albumin and significantly lower urine specific gravity when receiving torsemide as compared to furosemide, suggesting that torsemide is associated with a relatively greater diuretic response. ... Torsemide’s safety and superior efficacy have previously been established in human patients with CHF. ... The restoration of diuretic responsiveness and the accompanying volume depletion that follows torsemide administration might increase risk for renal insufficiency, and care should be taken to limit or reduce administration of concurrent diuretics such as hydrochlorothiazide and to closely monitor renal function when administering torsemide. The authors also recommend that owners of dogs receiving torsemide closely monitor their dog’s urine production, water consumption, and appetite. ... Torsemide has several attractive pharmacologic properties that might aid in the long-term treatment of canine heart disease. Clinical guidelines or recommendations involving torsemide should follow from prospective clinical trials demonstrating the long-term safety and potential superiority of torsemide over furosemide and other commonly used diuretics."

Distribution of syringomyelia along the entire spinal cord in clinically affected Cavalier King Charles Spaniels. Shenja Loderstedt, Livia Benigni, Kate Chandler, Jacqueline M. Cardwell, Clare Rusbridge, Christopher R. Lamb, Holger A. Volk. Vet J Dec 2011;190:359–363. Quote: "The objective of the present study was to define the anatomic distribution of SM in CKCS clinically affected by CM/SM. Our hypotheses were that in dogs with SM, (1)SM is present at multiple locations throughout the whole spinal cord; (2) the prevalence of SM is greatest in the cervical spine versus other regions; (3) the presence of SM in the cervical spinal cord is associated with the presence of SM in further caudal spinal cord regions; (4) the maximal syrinx size in each patient is in the cervical spine, and (5) there is a positive association between patient age and total syrinx size. ... 49  dogs were included in the present study. The median age of the dogs included in the study was 5 years (1.2–10.8 years). CM was present in all patients. ... All dogs in the present study were clinically affected. ... However, in our study SM was absent in 25% of dogs with clinical signs. ... There was no evidence of SM on MRI in 12/49 (25%) dogs. In all dogs with MRI evidence of SM (37/49; 75%), SM was present within the C1–C4 region (Figs. 2 and 3). Of those dogs with SM within C1–C4 region, 76% (28/37) also had SM within the C5–T1 and/ or T2–L2 regions, but only 49% (18/37) had SM within the L3–L7 region. ... The results of our investigation show that imaging only the cervical spine in clinically affected CKCSs is likely to underestimate the total syrinx size and the anatomical distribution of SM. The presence of cervical SM in all dogs with MRI evidence of SM could however justify the restricted imaging under screening purposes. ... The results of our study showed syrinx formation in all regions of the spinal cord with no significant differences of Sx between the cervical, cervicothoracic and thoracolumbar regions, but significantly smaller Sx in the caudolumbar spinal region. ... In our study Smax was most often seen within the C1–C4 region and, interestingly, also over T2–L2 vertebral bodies. ... We found that the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs. ... Conclusions: There is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region. Diagnostic imaging limited to the cervical spine in clinically affected CKCS is likely to underestimate the degree and severity of SM. It can be hypothesised that SM has a progressive nature in CKCS, which requires further characterisation."

Can breeding strategies modify or eliminate the syringomyelia phenotype? Colin J. Driver, Holger A. Volk. Vet Rec; Dec 2011;169:679-680. Quote: "Breeding strategies have existed for some time to limit the inheritance of common canine breed-specific diseases such as deafness in dalmatians, glaucoma in flat-coated retrievers and hip dysplasia in labrador retrievers. Progress in the control of these diseases relies on a greater understanding of their mode of inheritance (Wood and others 2004). Since the onset of using MRI in dogs in the late 1990s, the spinal cord disease syringomyelia has been reported to commonly affect several small breed dogs, notably the Cavalier King Charles spaniel (CKCS) and more recently the Griffon Bruxellois (Rusbridge 1997, Rusbridge and others 2009). In CKCS, Chiari-like malformations of the skull base and its content are ubiquitous and are the most prevalent predisposing cause for syringomyelia (Rusbridge and others 2006, Cerda-Gonzalez and others 2009). Chiari-like malformations and syringomyelia can be painful conditions. In the case of syringomyelia, pain is related to the formation of asymmetrical cavitations in the dorsal horn of the spinal cord (Rusbridge and others 2007). The severity of the mismatch between the brain and skull that typifies Chiari-like malformations is associated with the presence and severity of syringomyelia (Driver and others 2010a). For some years a hereditary basis for syringomyelia has been suggested in CKCS (Rusbridge and Knowler 2003). However, there had been limited research to suggest a mode of inheritance for the disease. On this basis, a ‘common sense’ approach to interim breeding guidelines was established in 2006 at an international Cavalier Club round table (Cappello and Rusbridge 2007), which is still used. The scheme hoped to limit symptomatic syringomyelia while not affecting genetic diversity. It was recommended that symptomatic dogs and young (less than two years) asymptomatic dogs with syringomyelia were not used for breeding."

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2012

Morphometric features of the craniocervical junction region in dogs with suspected Chiari-like malformation determined by combined use of magnetic resonance imaging and computed tomography. Dominic J. Marino, Catherine A. Loughin, Curtis W. Dewey, Leonard J. Marino, Joseph J. Sackman, Martin L. Lesser, Meredith B. Akerman. AJVR. Jan. 2012;73(1):105-111. Quote: "Objective: To objectively describe morphometric features of the craniocervical junction region of Cavalier King Charles Spaniels (CKCSs) and non-CKCS dogs with suspected Chiari-like malformation (CLM) and identify associations between these features and the presence of other malformations in this region. Animals: 216 CKCSs and 58 non-CKCS dogs. Procedures: Magnetic resonance and computed tomographic images of the head and craniocervical junction region of patients evaluated because of suspected CLM were assessed for cerebellar compression (CC), ventral spinal cord compression at the C1-C2 articulation (medullary kinking), and dorsal spinal cord compression at the C1-C2 articulation (dorsal compression). A compression index was calculated for each of these 3 locations in each dog. Multiple logistic regression analysis was performed to determine whether breed (CKCS vs non-CKCS) and compression index values were associated with the presence of other craniocervical junction abnormalities. Results: All 274 dogs had CC; medullary kinking was identified in 187 (68.2%) and dorsal compression was identified in 104 (38.0%). Atlantooccipital overlapping (AOO) was identified in 76 (27.7%) dogs. Breed of dog (CKCS vs non-CKCS) and value of CC index were the only significant predictors of AOO. The CKCSs had an almost 5-fold decrease in risk of AOO, compared with the non-CKCS dogs, and the risk of AOO nearly doubled for every 10% increase in CC index. Conclusions and Clinical Relevance: The anatomic abnormality responsible for CC was AOO in a substantial percentage of dogs suspected to have CLM. The CC index value may be used to help differentiate subtypes of craniocervical junction abnormalities in dogs."

Syringosubarachnoid shunt as a management for syringohydromyelia in dogs. L. Motta, G. C. Skerritt. J.Sm.An.Prac. Apr.2012; 53(4):205-212. Quote: "Objective: To evaluate retrospectively the efficacy of syringosubarachnoid shunt for the management of syringohydromyelia/syringomyelia. (The aim of the surgical procedures would be to decompress the neural tissue, to re-establish CSF flow and so decrease the syrinx size. In consequence, there may be reduction of neuropathic pain and spinal cord function may be promoted, providing that there has not been significant damage to the dorsal grey column and/or spinothalamic tracts.) (The S-S shunting drains the syrinx fluid into the subarachnoid space where the usual CSF circulation and absorption mechanisms exist. This reduces the syrinx size and eases the clinical signs associated with SHM/SM.) Methods: Eleven dogs (9 cavalier King Charles spaniels and 2 Yorkshire terriers) diagnosed with syringohydromyelia/syringomyelia by magnetic resonance imaging associated with Chiari-like malformation underwent placement of a syringosubarachnoid shunt at the cervical (nine dogs) or lumbar (two dogs) spinal cord. In one dog, a suboccipital decompression (foramen magnum decompression) was performed 4 months before inserting a syringosubarachnoid shunt (A silicone veterinary ocular lavage catheter by Smiths Medical was used to create the shunt.) (In nine cases, this was carried out at C3-C4 and in the remaining two cases at L1-L2). All dogs were evaluated neurologically a few hours after surgery, 2 weeks and 6 months postoperatively. Retrospectively, cases were assigned a preoperative and postoperative pain score. Results: There were no intra- or peri-operative complications. One dog (9%) was euthanased 5 weeks after surgery. Progressive neurological improvement was observed in nine dogs (81·8%) 2 weeks and 6 months postoperatively. No clinical improvement was seen in another dog (9%). One dog (9%) had replacement of the syringosubarachnoid shunt. Seven dogs (63·6%) were still alive 1 to 4 years (mean, 2·6 years) after surgery. Clinical Significance: Placement of a syringosubarachnoid shunt in the presence of a sufficiently large syrinx appears to be beneficial in dogs with Chiari-like malformation and associated syringohydromyelia/syringomyelia. (This small retrospective clinical study showed that S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results.)"

Increase in Cerebellar Volume in Cavalier King Charles Spaniels with Chiari-like Malformation and Its Role in the Development of Syringomyelia. Thomas A. Shaw, Imelda M. McGonnell, Colin J. Driver, Clare Rusbridge, Holger A. Volk. PLoS ONE; April 2012; 7(4):e33660. Quote: "Previous research in Cavalier King Charles Spaniels (CKCS) has found that Chiari-like malformation and syringomyelia (CM/SM) are associated with a volume mismatch between the caudal cranial fossa (CCF) and the brain parenchyma contained within. The objectives of this study were to i) compare cerebellar volume in CKCS (a “high risk’ group which frequently develops CM/SM), small breed dogs (medium risk – occasionally develop CM/SM), and Labradors (low risk – CM/SM not reported); ii) evaluate a possible association between increased cerebellar volume and CM/SM in CKCS; iii) investigate the relationship between increased cerebellar volume and crowding of the cerebellum in the caudal part of the CCF (i.e. the region of the foramen magnum). Volumes of three-dimensional, magnetic resonance imaging derived models of the CCF and cerebellum were obtained from 75 CKCS, 44 small breed dogs, and 31 Labradors. As SM is thought to be a late onset disease process, two subgroups were formed for comparison: 18 CKCS younger than 2 years with SM (CM/SM group) and 13 CKCS older than 5 years without SM (CM group). Relative cerebellar volume was defined as the volume of the cerebellum divided by the total volume of brain parenchyma. ... Our results show that the cerebellum is proportionately larger in CKCS (and a similar brainstem volume) when compared to Labradors and small breed dogs and also larger in young CKCS with CM and SM than in older CKCS with CM alone. ... Furthermore, the degree of cerebellar crowding in the caudal CCF is correlated with increased volume of the cerebellum in CKCS and this is not seen in small breed dogs or Labradors. These findings have implications for the understanding of the pathological mechanisms of CM/SM, and support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size.  ... In this study we found that CKCS under the age of 2 with SM (the CM/SM group) have an increased cerebellar volume when compared to CKCS over the age of 5 without SM. ... In CKCS there is an association between increased cerebellar volume and SM. These findings have implications for the understanding of the pathological mechanisms of CM/SM, and support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."

Effect of brachycephalic, mesaticephalic, and dolichocephalic head conformations on olfactory bulb angle and orientation in dogs as determined by use of in vivo magnetic resonance imaging. Aseel K. Hussein, Martin Sullivan, Jacques Penderis. Am.J.Vety.Res. July 2012; 73(7):946-951. Quote: "Objective: To determine the effect of head conformation (brachycephalic, mesaticephalic, and dolichocephalic) on olfactory bulb angle and orientation in dogs by use of in vivo MRI. Animals: 40 client-owned dogs [including 11 cavalier King Charles spaniels] undergoing MRI for diagnosis of conditions that did not affect skull conformation or olfactory bulb anatomy. Procedures: For each dog, 2 head conformation indices were calculated. Olfactory bulb angle and an index of olfactory bulb orientation relative to the rest of the CNS were determined by use of measurements obtained from sagittal T2-weighted MRI images. Results: A significant negative correlation was found between olfactory bulb angle and values of both head conformation indices. Ventral orientation of olfactory bulbs was significantly correlated with high head conformation index values (ie, brachycephalic head conformation). Conclusions and Clinical Relevance: Low olfactory bulb angles and ventral olfactory bulb orientations were associated with brachycephalia. Positioning of the olfactory bulbs, cribriform plate, and ethmoid turbinates was related. Indices of olfactory bulb angle and orientation may be useful for identification of dogs with extremely brachycephalic head conformations. Such information may be used by breeders to reduce the incidence or severity of brachycephalic-associated diseases."

Distribution of substance P and calcitonin gene-related peptide in the spinal cord of Cavalier King Charles Spaniels affected by symptomatic syringomyelia. Hilary Zhaoxu Hu, Clare Rusbridge, Fernando Constantino-Casas, Nick Jeffery. Research in Vet Sci; Aug 2012; 93(1):318-320. Quote: "The causes of clinical signs associated with syringomyelia in the Cavalier King Charles Spaniel (CKCS) are incompletely understood. In this study we compared expression of two pain-related neuropeptides: substance P (SP) and calcitonin gene related peptide (CGRP), in the spinal cord dorsal horn of normal dogs with that in CKCS with and without clinical signs of syringomyelia. There was a decrease in expression of both peptides in CKCS with ‘symptomatic’ syringomyelia that was also associated with significant asymmetry in SP-I and similar, though non-significant, asymmetry in CGRP-I compared with other groups. ... This current study provides evidence to suggest that the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected."

Comparison of the Relative Occipital Bone Volume Between Cavalier King Charles Spaniels with and Without Syringohydromyelia and French Bulldogs. M.J. Schmidt, M. Kramer, N. Ondreka. Sept. 2012. Vet. Radiology & Ultrasound. 53(5):540–544. Quote: "Our aim was to determine the relative volume of the occipital bone of Cavalier King Charles spaniels with and without syringohydromyelia and normal French bulldogs [as the weight of this breed met the range of the Cavalier King Charles spaniels (8–12 kg)] to reappraise the role of a possible insufficiency of the paraxial mesoderm in the pathogenesis of the caudal occipital malformation syndrome. Analysis of the occipital bone volume of 43 dogs [30 CKCSs] based on computed tomography datasets was performed. Volume was determined by means of three-dimensional models. Using manual segmentation of the occipital bone in sagittal, transverse, and dorsal images, the volume of the occipital bone and the rest of the skull was calculated. The absolute occipital bone volume was put in relation to the total skull volume, the occipital bone index. For the [15] Cavalier King Charles spaniels without syringomyelia, the median occipital bone index was 0.0681; for [15] Cavalier King Charles spaniels with syringomyelia, it was 0.0646 and for [13] French bulldogs, it was 0.0676. There was no global difference of the occipital bone index between examined groups (P = 0.4331). A reduced volume of the occipital bone was not found in Cavalier King Charles spaniels in general in comparison to French bulldogs, or in Cavalier King Charles spaniels with syringomyelia compared to Cavalier King Charles spaniels without syringomyelia. These results do not support occipital hypoplasia as a cause for syringomyelia development, challenging the paraxial mesoderm insufficiency theory. This also suggests that the term Chiari-like malformation, a term derived from human studies, is not appropriate in the Cavalier King Charles spaniel."

Questionnaire-based behaviour analysis of Cavalier King Charles spaniels with neuropathic pain due to Chiari-like malformation and syringomyelia. Lynda Rutherford, Annette Wessmann , Clare Rusbridge , Imelda M. McGonnell, Siobhan Abeyesinghe , Charlotte Burn , Holger A. Volk. Vet.J. 194(3):294-298. Quote: "Chiari-like malformation (CM)/syringomyelia (SM) is a disease complex recognised in Cavalier King Charles spaniels (CKCSs) that can lead to neuropathic pain (NeP). In humans, NeP is associated with anxiety, depression and reduced quality of life (QoL). In this study, databases of three specialist veterinary centres were searched and CKCS breed societies and health forums were contacted to identify CKCS with an imaging diagnosis of CM/SM. Owners completed questionnaires on behaviour, signalment, general health status, NeP and QoL. Data were analysed from 122 dogs out of 564 questionnaires completed, after incomplete questionnaires and data from dogs that had other potentially debilitating disease processes were excluded. ... Section 2: Questions asked in this section aimed to provide an insight into the dog’s general behaviour, any clinical manifestations of CM/SM and owner perceived QoL. Respondents were asked to what degree they had observed the following NeP signs of CM/SM in their dog on a semantic 5-point differential-type rating scale (... behaviour is exhibited 0 = never, 1 = seldom, 2 = sometimes, 3 = usually, 4 = always): (1) persistent, compulsive scratching with no underlying skin disease; (2) facial rubbing; (3) hypersensitivity to touch; (4) unexplained yelping; (5) reluctance to lift head; (6) reluctance to bend neck to eat; or (7) reluctance or pain when defaecating. Scores were averaged across these clinical signs to determine an individual NeP severity score (NeP score). The same scale was also used to establish a locomotory score and a score for sleeping/resting. To quantify owner perceived QoL, owners were asked to rate their dog’s overall QoL on a fixed scale as follows: 1 = could not be better; 2 = good; 3 = fairly good; 4 = neither good nor bad, 5 = fairly poor; 6 = poor; 7 = could not be worse or 8 = do not know. Section 3: ... This section had 11 broad categories: ‘stranger-directed’ aggression; ‘owner-directed’ aggression; ‘stranger-directed’ fear; non-social fear; ‘dog-directed’ fear; ‘separation-related’ behaviour; attachment or attention seeking behaviour; trainability; chasing behaviour; excitability; and pain sensitivity. The aforementioned sliding scale from 0 to 4 was used to quantify responses. ... NeP severity score was significantly and positively correlated with ‘stranger-directed’ fear (rS = 0.28), non-social fear (rS = 0.34), ‘separation-related’ behaviour (rS = 0.38), attachment behaviour (rS = 0.24), excitability (rS = 0.21) and proxy for pain sensation (rS = 0.29). Increased NeP was also significantly associated with decreased QoL (rS = 0.47), ability to settle (rS = 0.26) and willingness to exercise (rS = 0.50). Severity of NeP was positively associated with certain fear-associated behaviour and with decreased owner-perceived QoL. Thus, neurobehavioural changes should be considered in the management of NeP in CKCS with CM/SM."

Resolution of life-threatening dysphagia caused by caudal occipital malformation syndrome following foramen magnum decompressive surgery. KJ Graham, AP Black, PH Brain. Australian Vet,J. Aug 2012;90(8):297-300. Quote: "A Cavalier King Charles Spaniel was presented with acute onset, life-threatening dysphagia suspected to be secondary to medulla oblongata compression caused by caudal occipital malformation syndrome. The patient required urgent tracheostomy tube placement to remain stable and was subsequently cured of the presenting neurological deficits by foramen magnum decompressive surgery. Neurogenic dysphagia is a relatively common presenting sign in human Chiari malformation syndromes, but has not been described as a major clinical sign in veterinary patients. Caudal occipital malformation syndrome should be included in the differential diagnosis list for susceptible breeds presenting with dysphagia. Early recognition favours expeditious surgical intervention and a positive outcome in human patients, and this may also be the case in veterinary patients."

Assessment of the effects of adjunctive gabapentin on postoperative pain after intervertebral disc surgery in dogs. Sonja A. Aghighi, Andrea Tipold, Marion Piechotta, Piotr Lewczuk, Sabine B.R. Kästne. Veterinary Anaesthesia and Analgesia. Aug 2012. Quote: "Objective: To assess the effect of adjunctive gabapentin (GBP) on pain after thoracolumbar intervertebral disc surgery in dogs. Study design  Prospective, randomized, controlled, clinical, ‘blinded’ trial. Animals: Sixty-three client owned dogs undergoing hemilaminectomy. Methods: Dogs were assigned to two treatment groups. The GBP group received gabapentin 10 mg kg−1 orally every 12 hours starting before anaesthesia; the placebo (P) group received empty gelatin capsules. Background analgesia was initiated with intravenous levomethadone 0.6 mg kg−1 (as the combination ‘L-Polamivet) at anaesthesia induction, followed by a fentanyl patch and levomethadone 0.2 mg kg−1 subcutaneously every 8 hours for 24 hours. Pain was assessed by the short form of the Glasgow Composite Measure Pain Score (CMPS-SF) without the gait category, and by a Visual Analogue Scale (VAS). Serum GBP concentrations and cortisol concentrations were measured. Statistical analyses utilized chi square test, Kolmogorov-Smirnov test, two-way analysis of variances for repeated measurements, Wilcoxon test and Friedmann test as relevant. Correlations were tested by Spearman’s and Pearson’s correlation coefficient. p < 0.05 was considered significant. Results: Median CMPS-SF was lower in group GBP than in group P on days 0.5, 1, 4 and 5. However, CMPS-SF and VAS were not significantly different between groups. Both pain scores decreased significantly over time. Cortisol concentrations were not significantly different between groups. Minimum serum concentrations of GBP fell below the detection limit of 1 μg mL−1 in 6 of 29 and 7 of 28 dogs at 24 and 72 hours, respectively. Conclusions and clinical relevance: 10 mg kg−1 GBP orally twice a day did not result in a detectable reduction in pain behaviour compared to background opioid analgesia alone, although a trend to lower pain levels (p < 0.1) was present. Further studies are needed to determine if this is related to effective background analgesia or an ineffective dose of GBP."

Malformation Chiari-Like : l’investigation d’une maladie complexe par l’utilisation d’un modèle canin. Philippe Lemay, Zoha Kibar. Thesis. Univ. Montreal. Aug. 2012. Quote: "Chiari I malformation (CMI) represents a common congenital abnormality of the craniocerebral junction with an estimated incidence of 1 in 1280. CMI is characterized by a descent of the cerebellar tonsils into the foramen magnum, often in association with syringomyelia. The developmental defect in CMI is thought to be the result of an underdeveloped occipital bone and small posterior fossa. The etiology of CMI is thought to be multifactorial involving genetic factors. CMI in humans is similar to a condition in the dog called Chiari-like malformation (CM) that is particularly common in the Griffon Bruxellois (GB) breeds. A genome wide association study on a 56 GB cohort followed by a fine mapping in a 217 GB cohort have identified a locus on chromosome 2 that was strongly associated with CM (22 SNPs, P value= 7 x 10-8). Haploview analysis of this locus identified a haplotype of 1.9 Mb that was more frequent in non-affected dogs. A second genome wide association study in a 113 GB cohort lead to the identification of another locus on chromosome 13 that was strongly associated with CM (25 SNPs , P value= 3 x 10-7). Analysis of this region identified a 4Mb haplotype that was more frequent in non-affected dogs. Our study constitutes the first essential step towards identification of the causative genes in CM. Our study provides an entry point for better understanding of the molecular genetic mechanisms underlying the pathogenesis of human CMI."

Volume reduction of the jugular foramina in Cavalier King Charles Spaniels with syringomyelia. Martin J Schmidt, Nele Ondreka, Christoph Rummel, Holger Volk, Maren Sauerbrey and Martin Kramer. Vety.Research. Sept. 2012; 8:158. Quote: "Background: Understanding the pathogenesis of the chiari-like malformation in the Cavalier King Charles Spaniel (CKCS) is incomplete, and current hypotheses do not fully explain the development of syringomyelia (SM) in the spinal cords of affected dogs. This study investigates an unconventional pathogenetic theory for the development of cerebrospinal fluid (CSF) pressure waves in the subarachnoid space in CKCS with SM, by analogy with human diseases. In children with achondroplasia the shortening of the skull base can lead to a narrowing of the jugular foramina (JF) between the cranial base synchondroses. This in turn has been reported to cause a congestion of the major venous outflow tracts of the skull and consequently to an increase in the intracranial pressure (ICP). Amongst brachycephalic dog breeds the CKCS has been identified as having an extremely short and wide braincase. A stenosis of the JF and a consequential vascular compromise in this opening could contribute to venous hypertension, raising ICP and causing CSF jets in the spinal subarachnoid space of the CKCS. In this study, JF volumes in CKCSs with and without SM were compared to assess a possible role of this pathologic mechanism in the development of SM in this breed. Results: Computed tomography (CT) scans of 40 CKCSs > 4 years of age were used to create three-dimensional (3D) models of the skull and the JF. Weight matched groups (7--10 kg) of 20 CKCSs with SM and 20 CKCSs without SM were compared. CKCSs without SM presented significantly larger JF -volumes (median left JF: 0.0633 cm3; median right JF: 0.0703 cm3; p < 0.0001) when compared with CKCSs with SM (median left JF: 0.0382 cm3; median right JF: 0.0434 cm3; p < 0.0001). There was no significant difference between the left and right JF within each group. Bland-Altman analysis revealed excellent reproducibility of all volume measurements. Conclusion: A stenosis of the JF and consecutive venous congestion may explain the aetiology of CSF pressure waves in the subarachnoid space, independent of cerebellar herniation, as an additional pathogenetic factor for the development of SM in this breed."

Cervicothoracic syringohydromyelia associated with a prosencephalic mass in a dog. D. Szabo, T. C. Saveraid, S. Rodenas. J.Sm.Anim.Prac. Oct. 2012;53(10):613-617. Quote: "A five-year-old, female, neutered boxer, with neuroanatomical signs consistent with a C1-C5 myelopathy, was diagnosed with a prosencephalic mass and associated severe cervicothoracic syringohydromyelia. After treatment with corticosteroids and lomustine, neurological examination was normal. Imaging repeated three months later showed significant reduction in both the size of the mass and the syringohydromyelia. To the authors’ knowledge, this is the first reported case of a dog with syringohydromyelia secondary to a rostral brain mass that had clinical signs on presentation solely due to the syrinx, and the first reported case in a dog of partial resolution of syringohydromyelia after treatment solely with chemotherapy."

Chiari-like malformation: A substantive health and welfare problem in the Cavalier King Charles Spaniel. Jacques Penderis. Vety.J. Feb. 2013;195(2):133-134. Quote: "... In particular, it has been suggested that selection for a specific head phenotype has inadvertently resulted in Chiari-like malformation in this breed. Examination of the genetics of Chiari-like malformation in the CKCS indicates that this may be an oversimplification of the problem, as the disease is likely to represent a complex oligogenic trait with moderately high heritability (Lewis et al., 2010). Irrespective of the cause, Chiari-like malformation is a substantive problem in the breed, estimated to affect around 95% of CKCS (Dewey and Rusbridge, 2008). Although many cases are clinically silent, characteristic morphological changes are present in the brains of affected animals (Carrera et al., 2009). ... The poor reputation that the breed endures is, in part, unjustified. Instead of shying away from publicity, many CKCS breed clubs have worked hard to raise public awareness of health issues in the breed and raise funds to support clinical research into disease prevention. This proactive attitude and willingness to engage with researchers has already delivered positive results, with the release of a genetic test for Episodic Falling in CKCS by the Animal Health Trust (UK) in April, 2011 (Forman et al., 2012) and the development of a joint Kennel Club and British Veterinary Association screening programme for Chiari- like malformation in CKCS in the UK. Instead of criticising CKCS breeders, we should be supportive of their efforts to understand breed-related problems and help them work to improve the health and welfare of the breed. ... The high prevalence of Chiari-like malformation in the breed and the confirmation that brain morphology is directly influenced by head phenotype (Hussein et al., 2012), suggests that Chiari-like malformation in the CKCS is likely to be the inadvertent consequence of misguided breeder selection to emphasise certain cranial features deemed to be desirable. The high breed prevalence of Chiari-like malformation (estimated at 95%) points to limited genetic diversity within the CKCS, resulting in major difficulties if breeding away from conformations associated with Chiari-like malformation is attempted in the future."

Long-term outcome of Cavalier King Charles Spaniels  with clinical signs associated with Chiari-like malformation and syringomyelia. I. N. Plessas, C. Rusbridge, C. J. Driver, K. E. Chandler, A. Craig, I. M. McGonnell, D. C. Brodbelt, H. A. Volk. Vet.Rec.Oct. 2012;doi: 10.1136/vr.100449. Quote: "The disease complex Chiari-like malformation (CM) and syringomyelia (SM) has been associated with the development of neuropathic pain (NeP), and commonly affects Cavalier King Charles spaniels (CKCS). It is not yet fully understood how CM/SM causes NeP. However, histopathological studies of SM in CKCS have found that dogs which had expressed signs of NeP suffered an asymmetrical syrinx with profound alteration of the structure of the dorsal horn laminae, and had reduced expression of the pain-related neuropeptides substance P, and calcitonin gene-related peptide (Hu and others 2012a).This prospective cohort study followed 48 CKCSs [between ages 1 year and 13 years] with CM and/or SM [Nine of the 48 dogs had CM only] and clinical signs suggestive of NeP for a period of 39 (±14.3) months from diagnosis. At the end of the study, 36 dogs were still alive; five dogs died of an unrelated or unknown cause, and seven were euthanased due to severe clinical signs suggestive of NeP. During the follow-up period, the clinical signs of scratching, facial rubbing behaviour, vocalisation and exercise ability were evaluated. Nine out of 48 dogs stopped scratching (P<0.001), but there was no statistically significant change in the number of dogs exhibiting exercise intolerance, vocalisation or facial rubbing behaviour. The overall severity of clinical signs based on a visual analogue scale (VAS) (0 mm: no clinical signs 100 mm: severe clinical signs) increased (from median 75 mm (interquartile ranges (IQR) 68–84) to 84 mm (IQR 71.5–91), P<0.001). A quarter of the dogs were static or improved. In general, the majority of the owners felt that the quality of life of their dogs was acceptable. Medical treatments received were gabapentin or pregabalin and/or intermittently, carprofen. The owner's perception of their animal's progress, and progress based on VAS, had strong positive correlation (Spearman's rank correlation (sr) 0.74, P<0.001). Overall, this study suggests that clinical signs suggestive of NeP progress in three-quarters of CKCSs with CM and/or SM. ... Traditionally, clinical signs suggestive of NeP in CKCS have been associated with CM and SM, but from our study, we found that CM only may contribute to these signs, too. ... Finally, it is important to mention that this study is documenting the progression of a specific set of clinical signs in a group of dogs with CM and/or SM, and not the progression of the disease itself."

Changes over time in craniocerebral morphology and syringomyelia in cavalier King Charles spaniels with Chiari-like malformation. Colin J Driver, Luisa De Risio, Sarah Hamilton, Clare Rusbridge, Ruth Dennis, Imelda M McGonnell, Holger A Volk. BMC Vet. Research Nov. 2012, 8:215. Quote: "Background: Chiari-like malformation (CM) and syringomyelia is a neurological disease complex with high prevalence in cavalier King Charles spaniels (CKCS). The natural progression of this disease with time has not been described. The objectives of this study were to i) determine if syringomyelia progresses with time ii) determine if features of craniocrebral morphology previously associated with CM are progressive (including caudal cranial fossa volume, caudal cranial fossa parenchymal volume, ventricular dimensions, height of the foramen magnum and degree of cerebellar herniation). A retrospective morphometric analysis was undertaken in 12 CKCS with CM for which repeat magnetic resonance images were available without surgical intervention. Results: The maximal syrinx width, height of the foramen magnum, length of cerebellar herniation and caudal cranial fossa volume increased over time. Ventricular and caudal fossa parenchymal volumes were not significantly different between scans. Conclusions: The results of this study suggest that syringomyelia progresses with time. Increased caudal cranial fossa volume may be associated with active resorption of the supraoccipital bone, which has previously been found in histology specimens from adult CKCS. We hypothesise that active resorption of the supraoccipital bone occurs due to pressure from the cerebellum. These findings have important implications for our understanding of the pathogenesis and variable natural clinical progression of CM and syringomyelia in CKCS."

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2013

Caudal cranial fossa partitioning in Cavalier King Charles spaniels. T. A. Shaw, I. M. McGonnell, C. J. Driver, C. Rusbridge, H. A. Volk. Vety.Rec. Feb. 2013. Quote: "Here, we report that the morphology of the canine skull is affected by variation in hindbrain volume. Important differences exist between CKCS [cavalier King Charles spaniels], SB [small breeds] and LD [Labradors] that are pertinent to the pathological mechanisms of CM/SM. ... A retrospective study of MRI scans of CKCS, SB and LD was performed. ... We found that CKCS had a relatively large pars rostralis [tentorium cerebelli] volume ... and relatively small pars caudalis [occipital bones] volume ... when compared with LD and SB ... . These findings suggest that in CKCS there is a reduction in occipital skull volume and an increase in the volume bounded by the tentorium cerebelli. Furthermore, pars caudalis volume was reduced in the CM/SM group ... compared with CM group ..., which suggests an association between reduced volume in the caudal part of the CCF and the development of SM .... The pars media of the SB group ... was significantly smaller than the LD ... and CKCS groups ... . Our results also revealed important differences in the relationship between hindbrain volume and CCF morphology... . These findings suggest that SB and LD compensate for variations in hindbrain volume by modifying the growth of the occipital skull, whereas in CKCS, occipital bone development is insensitive to changes in hindbrain volume. We infer from these results that increased hindbrain volume in CKCS causes the tentorium cerebelli to compensate by bulging in a rostral direction. A similar phenomenon, an increase in the angle of the tentorium, has been widely reported in humans with Chiari malformation I  ... . The data support the hypothesis that CM/SM in CKCS is a multifactorial disease process governed by the effects of increased hindbrain volume and impaired occipital bone development. The present authors recently reported that CM/SM is linked to increased cerebellar volume (Shaw and others 2012). In view of this, the aetiopathogenesis [cause and development] of CM/SM may equivocally be mediated by conditions independently affecting the developing occipital bones and cerebellum, or by dysregulation of a signalling mechanism coordinating the growth of the developing hindbrain and occipital skull.

The association between Chiari-like malformation, ventriculomegaly and seizures in cavalier King Charles spaniels. C.J. Driver, K. Chandler, G. Walmsley, N. Shihab, H.A. Volk. Vet.J. February 2013;195(2):235-237; doi: 10.1016/j.tvjl.2012.05.014 . Quote: Cavalier King Charles spaniels (CKCSs) with Chiari-like malformation (CM) and associated seizures are frequently diagnosed with idiopathic epilepsy. There could be an association between ventriculomegaly (V) or caudal fossa overcrowding (CCFP) and seizures. A retrospective case-control study was performed using MRI to investigate the possible association between these morphological abnormalities and seizures. Seizure semiology and, where possible, electroencephalographic (EEG) abnormalities were documented. Eighty-five CKCS with CM were included, 27 with seizures. There was no association between V or CCFP and seizures (P = 0.10 and 0.71, respectively). Seizures were classified as having partial onset [meaning that they occur in in one area of the brain, unlike generalized seizures which typically affect nerve cells throughout the brain] in 61% of individuals in the study population (95% CI 42.41–76.43%). Another cause of recurrent seizures in CKCS (such as familial epilepsy) is suspected, as previously reported.

Syringomyelia and Chiari Malformation in Cavalier King Charles Spaniels – Magnetic Resonance Imaging, Pharmacological and Surgical Treatment. Andrzej Pomianowski, Zbigniew Adamiak. Bulletin of Vet.Inst.Pulway. March 2013;57(1):131-133. Quote: "The aim of the study was to describe images of syringomyelia and Chiari malformation in Cavalier King Charles Spaniels, produced by low field magnetic resonance sequences, and to discuss the results of pharmacological and surgical treatment performed in dogs with the disease. Nine Cavalier King Charles Spaniels aged from 2 to 5 years, including seven females and two males, with Chiari malformation and syringomyelia, which were subjected to low-field magnetic resonance imaging (MRI) test, were described. The results of MRI examinations were presented. The outcomes of pharmacological therapy involving two dogs and surgical treatment of one dog were also described. The applied treatments produced positive short-term outcomes, and they eliminated the clinical symptoms of the disease."

Craniocervical junction abnormalities in dogs. C W Dewey, D J Marino, C A Loughin. New Zealand Vet. J. April 2013;61(4):202-211. Quote: "Craniocervical junction abnormality (CJA) is a term that encompasses a number of developmental anatomical aberrations at the region of the caudal occiput and first two cervical vertebrae. Chiari-like malformation appears to be the most common CJA encountered in dogs, and there has been a tremendous amount of clinical investigation into this disorder in recent years. Other abnormalities in this region include atlanto-occipital overlap, dorsal constriction at C1/C2 and atlantoaxial instability. This review article presents an overview of the current understanding of CJA in dogs, as well as medical and surgical treatment options available."

A Potential Role for Substance P and Interleukin-6 in the Cerebrospinal Fluid of Cavalier King Charles Spaniels with Neuropathic Pain. M.J. Schmidt, J. Roth, N. Ondreka, M. Kramer, and C. Rummel. J.Vet.Intern.Med. May 2013; 27(3):530-535. Quote: "Background: Neuropathic pain can be a clinical sign in Cavalier King Charles Spaniels (CKCS) with syringomyelia. The pathophysiology of this pain is not fully understood. Hypothesis: Neuropathic pain in CKCS is a result of a euroinflammatory process. Animals: Twenty-six client-owned dogs: 15 dogs with clinical signs of cervical hyperesthesia (group 1), and 11 dogs without of clinical signs (group 2). Methods: Dogs were examined by magnetic resonance imaging (MRI). Interleukin-6, tumor necrosis factor alpha, and substance P were measured in CSF and compared with morphological findings on MRI and clinical pain scores. Results: All dogs without clinical signs had symmetrical syringomyelia, whereas in the group with pain, 6 dogs had symmetrical and 9 dogs had asymmetrical syringomyelia. Pain and syringomyelia asymmetry were correlated, and a strong association between pain and dorsal horn involvement of syringomyelia was observed. There was no significant difference between the mean width of the syringomyelia in dogs with or without pain. The concentrations of interleukin-6 and substance P were significantly higher in dogs with neuropathic pain. Tumor necrosis factor alpha was not detected in either group. Concentrations of substance P were significantly higher in dogs with asymmetrical syringomyelia or dorsal horn involvement, whereas interleukin-6 concentrations were not significantly different between groups. Conclusion: Release of interleukin-6 and substance P may initiate proinflammatory effects leading to development of persistent pain in CKCSs with syringomyelia."

Magnetic Resonance Imaging (MRI) Spinal Cord and Canal Measurements in Normal Dogs. S. Hecht, M. M. Huerta, R. B. Reed. Anatomia Histologia Embryologia. March 2013. Quote: "The goal of this study was to establish Magnetic resonance imaging (MRI) reference ranges for spinal measurements in normal dogs. Forty dogs (1–10 kg, 11–20 kg, 21–30 kg, > 30 kg; 10 dogs per category) underwent spinal MRI. Measurements were performed on sagittal T2-W images at the level of the 4th thoracic vertebra (T4), the 9th thoracic vertebra (T9) and the 3rd lumbar vertebra (L3). Spinal canal diameter (mm) ranged from 6.07 ± 0.63 (1–10 kg) to 8.27 ± 1.15 (> 30 kg) at the level of T4; 6.55 ± 0.61 (1–10 kg) to 9.04 ± 1.26 (> 30 kg) at the level of T9; and 6.80 (6.47–7.00; 1–10 kg) to 9.00 (7.90–9.73; > 30 kg) at the level of L3. There were significant differences (P < 0.05) in spinal canal diameter between groups. Mean spinal cord diameter (mm) ranged from 4.46 ± 0.51 (11–20 kg) to 4.70 ± 0.35 (1–10 kg) at the level of T4; 4.41 ± 0.50 (> 30 kg) to 4.85 ± 0.57 (1–10 kg) at the level of T9; and 4.52 ± 0.51 (> 30 kg) to 5.14 ± 0.68 (1–10 kg) at the level of L3. There were no significant differences in spinal cord diameter between groups. Spinal cord-to-spinal canal ratio varied significantly, ranging from 0.51 ± 0.08 (> 30 kg at L3) to 0.78 (0.69–0.80; 1–10 kg at T4) (P < 0.05). These findings are important when using MRI to evaluate patients with suspected diffuse spinal cord disease."

Syringomyelia and Chiari Malformation in Cavalier King Charles Spaniels – Magnetic Resonance Imaging, Pharmacological and Surgical Treatment. Andrzej Pomianowski, Zbigniew Adamiak. Bulletin of Vet. Institute in Pulawy. March 2013;57: 131-133. Quote: "Nine dogs [all cavalier King Charles spaniels] with Chiari malformation and syringomyelia, which were subjected to low-field magnetic resonance imaging (MRI) test, were described. The results of MRI examinations were presented. The outcomes of pharmacological therapy involving two dogs and surgical treatment of one dog were also described. The applied treatments produced positive short-term outcomes, and they eliminated the clinical symptoms of the disease. ... The results of the study and published data indicate that magnetic resonance imaging is essential for diagnosing Chiari-like malformations and syringomyelia. Caudal cerebellar herniation was observed in all cases, including the patients examined upon the owners' request to obtain a certificate for breeding purposes. In this group of dogs, herniation was found in all patients, but none of the owners reported any neurological disorders. ... In the group of three dogs with neurological symptoms, two owners decided to subject their animals to pharmacological treatment, and one owner opted for surgery. In pharmacologically treated dogs, clinical symptoms subsided during the observation period. According to the owner of the surgically treated dog, the symptoms of the disease subsided after treatment and the dog fully recovered. ... The results delivered by both treatment models seem to be promising, albeit in a short-term perspective. The owners of the studied animals broke off contacts with the clinics performing the treatment, thus shortened the clinical observation period."

Venous sinus volume in the caudal cranial fossa in Cavalier King Charles spaniels with syringomyelia. Joe Fenn, Martin J. Schmidt, Harriet Simpson, Colin J. Driver, Holger A. Volk. Vet.J. June 2013; doi: 10.1016/j.tvjl.2013.05.007 . Quote: "Syringomyelia (SM) in Cavalier King Charles spaniels (CKCS) has a complex pathophysiology. Recent studies support a relationship between altered venous drainage and cerebrospinal fluid flow dynamics. The aim of this study was to evaluate the relationship between venous sinus and parenchymal volume within the caudal cranial fossa (CCF) in CKCS with SM (n = 22) and without SM (n = 12) using magnetic resonance venography (MRV). MRI and MRV images were used to obtain volumetric calculations of CCF volume, as well as the percentage of this volume occupied by parenchyma (CCFP%) and venous sinuses (CCFV%). In CKCS with SM, CCFP% was significantly higher, whilst CCFV% was significantly lower than in CKCS without SM. These results support a role for reduced venous drainage and parenchymal ‘overcrowding’ of the CCF in the pathophysiology of SM."

Assessment of cerebellar pulsation in dogs with and without Chiari-like malformation and syringomyelia using cardiac-gated cine magnetic resonance imaging. C.J. Driver, V. Watts, A.C. Bunck, L.M. Van Ham, H.A. Volk. Vet.J. June 2013. Quote: "Canine Chiari-like malformation (CM) is characterised by herniation of part of the cerebellum through the foramen magnum. In humans with Chiari type I malformation (CM-I), abnormal pulsation of the cerebellum during the cardiac cycle has been documented and is pivotal to theories for the pathogenesis of syringomyelia (SM). In this retrospective study, cardiac-gated cine balanced fast field echo (bFEE) magnetic resonance imaging (MRI) was used to assess pulsation of the brain in dogs and to objectively measure the degree of cerebellar pulsation with the neck in a flexed position. Overall, 17 Cavalier King Charles Spaniels (CKCS) with CM, including eight with SM and nine without SM, were compared with six small breed control dogs. Linear regions of interest were generated for the length of cerebellar herniation from each phase of the cardiac cycle and the degree of cerebellar pulsation was subsequently calculated. Age, bodyweight and angle of neck flexion were also compared. CKCS with CM and SM had significantly greater pulsation of the cerebellum than control dogs (P = 0.003) and CKCS with CM only (P = 0.031). There was no significant difference in age, bodyweight and angle of neck flexion between the three groups. Cardiac-gated cine bFEE MRI permitted the dynamic visualisation of cerebellar pulsation in dogs. These findings support the current theories regarding the pathogenesis of SM secondary to CM and further highlight the similarities between canine CM and human CM-I."

Comparison of Closure Times for Cranial Base Synchondroses in Mesaticephalic, Brachycephalic, and Cavalier King Charles Spaniel Dogs. Martin J. Schmidt, Holger Volk, Melanie Klingler, Klaus Failing, Martin Kramer, Nele Ondreka. Vet.Radiology & Ultrasound. Sept. 2013;54(5):497-503. Quote: "Premature closure of cranial base synchondroses has been proposed as the mechanism for brachycephaly in dogs and caudal occipital malformation syndrome (COMS) in Cavalier King Charles Spaniels. The purpose of this retrospective study was to compare times of closure for cranial base synchondroses in mesaticephalic, brachycephalic, and Cavalier King Charles Spaniel dogs. Cranial magnetic resonance imaging studies were retrieved for client-owned dogs less than 18 months of age. Breed, age, skull conformation, and the open or closed state of cranial base synchondroses were independently recorded by two observers. For dogs with a unanimous observer agreement, regression analysis was used to test effects of age and gender on the open or closed status of synchondroses and differences between groups. A total of 174 dogs were included in MRI interpretations and 165 dogs were included in the regression analysis. Statistically significant differences in closure time of the spheno-occipital synchondrosis were identified between brachycephalic and mesaticephalic dogs (P = 0.016), Cavalier King Charles Spaniels and mesaticephalic dogs (P < 0.0001), and Cavalier King Charles Spaniels and brachycephalic dogs (P = 0.014). Findings from the current study supported the theory that morphological changes leading to the skull phenotype of the Cavalier King Charles Spaniels could be due to an earlier closure of the spheno-occipital synchondrosis." See also, Retrospective analysis of the joint conclusion of synchondroses base of the skull in dogs of various breeds with special consideration of Cavalier King Charles Spaniels.

Variations in Magnetic Resonance Venographic Anatomy of the Dorsal Dural Venous Sinus System in 51 Dogs. Joe Fenn, Richard Lam, Patrick J. Kenny. Vet.Radiology&Ultrasound. June 2013. Quote: "Variations in intracranial dural venous sinus anatomy have been widely reported in humans, but there have been no studies reporting this in dogs. The purpose of this retrospective study was to describe variations in magnetic resonance (MR) venographic anatomy of the dorsal dural venous sinus system in a sample population of dogs with structurally normal brains. Medical records were searched for dogs with complete phase contrast, intracranial MR venograms and a diagnosis of idiopathic epilepsy. Magnetic resonance venograms were retrieved for each dog and characteristics of the dorsal dural sinuses, symmetry of the transverse sinuses and other anatomic variations were recorded. A total of 51 dogs were included [including 8 cavalier King Charles spaniels]. Transverse sinus asymmetry was present in 58.8% of the dogs, with transverse sinus hypoplasia seen in 39.2%, and aplasia in 23.5% of dogs. For 70.6% of dogs, at least one anatomic variation in the dorsal sagittal sinus was observed, including deviation from the midline (33.3%) and collateral branches from either the dorsal sagittal sinus or dorsal cerebral veins (54.9%). In 5 dogs (9.8%) a vessel was also identified running from the proximal transverse sinus to the distal sigmoid sinus, in a similar location to the occipital sinus previously reported in children. Findings from this study indicated that, as in humans, anatomic variations are common in the intracranial dural venous sinus system of dogs. These anatomic variations should be taken into consideration for surgical planning or diagnosis of cerebrovascular disease."

Assessment of cerebellar pulsation in dogs with and without Chiari-like malformation and syringomyelia using cardiac-gated cine magnetic resonance imaging. C.J. Driver, V. Watts, A.C. Bunck, L.M. Van Ham, H.A. Volk. Vet.J. June 2013. Quote: "Canine Chiari-like malformation (CM) is characterised by herniation of part of the cerebellum through the foramen magnum. In humans with Chiari type I malformation (CM-I), abnormal pulsation of the cerebellum during the cardiac cycle has been documented and is pivotal to theories for the pathogenesis of syringomyelia (SM). In this retrospective study, cardiac-gated cine balanced fast field echo (bFEE) magnetic resonance imaging (MRI) was used to assess pulsation of the brain in dogs and to objectively measure the degree of cerebellar pulsation with the neck in a flexed position. Overall, 17 Cavalier King Charles Spaniels (CKCS) with CM, including eight with SM and nine without SM, were compared with six small breed control dogs. Linear regions of interest were generated for the length of cerebellar herniation from each phase of the cardiac cycle and the degree of cerebellar pulsation was subsequently calculated. Age, bodyweight and angle of neck flexion were also compared. CKCS with CM and SM had significantly greater pulsation of the cerebellum than control dogs (P = 0.003) and CKCS with CM only (P = 0.031). There was no significant difference in age, bodyweight and angle of neck flexion between the three groups. Cardiac-gated cine bFEE MRI permitted the dynamic visualisation of cerebellar pulsation in dogs. These findings support the current theories regarding the pathogenesis of SM secondary to CM and further highlight the similarities between canine CM and human CM-I."

Drug Interactions in Polypharmacy. Lauren A. Trepanier. Clinician's Brief. June 2013:23-26.

Chiari-Like Malformation in Dogs. Dominic J. Marino, Curtis W. Dewey. The Chiari Malformations; Chapter 11. Springer NY 2013. Quote: "The Chiari I malformation in humans and Chiari-like malformation in dogs (CLM) is a condition in which the cerebellum descends out of the foramen magnum affecting normal cerebral spinal fluid (CSF) flow. It is considered to be a developmental abnormality and is commonly confused with many other conditions. Chiari-like malformation in dogs affected approximately 85 % of Cavalier King Charles Spaniels evaluated, as reported in the most recent studies. The specific cause has not been determined; however, because of an abnormal shape or reduced skull size in the caudal occipital region, part of the cerebellum is forced through the foramen magnum, altering CSF flow patterns. Changes in CSF dynamics result in an abnormal accumulation of fluid within the substance of the spinal cord called a 'syrinx.' The diagnosis of CLM in dogs and Chiari type I in humans can only be confirmed by MRI which is essential for determining the cause of syringomyelia. Current concepts in the diagnosis and treatment of Chiari-like malformation in dogs will be discussed."

An update on the pathogenesis of syringomyelia secondary to Chiari-like malformations in dogs. C.J. Driver, H.A. Volk, C. Rusbridge, L.M. Van Ham. Vet.J. Aug. 2013. Quote: "Syringomyelia (SM) is a spinal cord disease that can cause neuropathic pain in dogs. The pathogenesis of SM secondary to Chiari-like malformation (CM) has been the focus of intense research in recent years. The gulf in our understanding of CM/SM in dogs relative to the analogous human condition has progressively narrowed. CM is primarily a disease of abnormal geometric morphometry affecting the caudal cranial fossa and the brain parenchyma contained within it. This review describes how advanced imaging techniques have revealed a series of morphometric abnormalities associated with CM/SM. The series is presented in a logical order to help describe the pathogenesis of CM and the subsequent formation of syringes, with particular reference to the concepts of craniospinal compliance and cerebrospinal fluid pulse pressure timing. ... Mechanical compliance determines the ability of a system to accommodate a change in volume in the face of pressure changes. Craniospinal compliance is the sum of the ability of both the cranial and spinal compartments to accommodate changes in parenchymal, blood or CSF volumes, which all exist in a state of dynamic equilibrium. Compliance is primarily concerned with the dimensions of the skull, but is influenced by several other factors, including CSF volume, free CSF flow, the integrity of the vasculature, space occupying lesions, and autonomic regulation of blood flow. ... Where craniospinal compliance is generally reduced, for example due to failed CSF absorption into the venous sinuses, hydrocephalus and communicating SM occur. ... We propose that CM is responsible for reduced compliance. Further, reduced cranial compliance could result in a larger pressure gradient between the cranial and spinal systems. ... There are two observable outcomes of reduced compliance. Firstly, reduction of the CSF space at the foramen magnum could lead to the retention of CSF in the head, which would otherwise be free to move through the foramen magnum. Ventriculomegaly is a common observation in CKCS with CM and in one study, the volume of the ventricular system was positively correlated with the severity of SM, suggesting a shared pathogenesis. However, it should be noted that large ventricles are common in small breed dogs. Secondly, reduced cranial compliance might affect the transition of pressure between the blood and CSF compartments of the cranial and spinal systems. This could explain the turbulent CSF flow patterns that were observed by Cerda-Gonzalez et al. (2009b) at the foramen magnum. The increased cerebellar pulsation observed in CKCS with SM by Driver et al. (2013) could also be associated with altered pressure and compliance; however, it remains unclear whether this is a cause or effect of this change. ... Clinically, the condition remains frustrating to treat given its variable natural progression. In theory, surgical treatment of CM in dogs might be appropriate to restore compliance but it is important to emphasise that there is little information to guide the clinician regarding whether such major surgery is appropriate or necessary when mild clinical signs are apparent. Despite progressive neuropathic pain in the majority of cases, most dog owners still consider their pets to have a good quality of life with medical therapy. Further research might focus on advanced imaging techniques to assess the clinical correlates of altered CSF hydrodynamics. Moreover, phase contrast cMRI has been used to assess craniospinal compliance, which could be applied in dogs. Importantly, improved descriptions of the genes involved in formation of the hindbrain and CCF could help to guide breeding schemes, which are problematic given the high prevalence of the disease."

Chiari-like malformations: Is compliance the issue? Cerda-Gonzalez, S. Vet.J. Aug. 2013.

Retrospektive Betrachtung des Fugenschlusses der Synchondrosen der Schädelbasis bei Hunden verschiedener Rassen unter besonderer Berücksichtigung des Cavalier King Charles Spaniels. (Retrospective analysis of the joint conclusion of synchondroses base of the skull in dogs of various breeds with special consideration of Cavalier King Charles Spaniels.) Melanie Klinger. VVB Laufersweiler Verlag. 2013. Quote: "The cranial base has a significant role for the development of the entire craniofacial as well as for the central nervous system. Growth of the skull base occurs in the growth plates, the so-called synchondroses, and ends with the ossification of the synchondroses, which remain as synostoses. ... An extreme type of skull is shown by dogs with a brachycephaly in which a shortening of the longitudinal axis with compensatory broadening occurs. The Cavalier King Charles Spaniel (CKCS) shows a very pronounced form of this reduced longitudinal expansion. Furthermore, the CKCS shows a predisposition for the disease complex of Chiari-like malformation (CM). The sphenooccipital synchondrosis is the main contributor to the longitudinal growth of the skull. The objective of the present study was to determine the closure time in which ossification for the dogs sphenooccipital synchondrosis occurs. In regards to the different skull types the decision was made to divide the participants into three groups. Group 1 consisted of mesocephalic dogs which have a skull type close to the prototype of the wolf. The second group was composed of brachycephalic breeds. Considering the extreme brachycephaly of the CKCS and the cumulation of CM in this breed, a separate grouping of these dogs seemed necessary. The study population consisted of 67 mesocephalic and 24 brachycephalic dogs as well as of 58 animals belonging to the CKCS breed. The maximum age was 18 months. The statistical analysis results clearly showed a difference of the ossification time at the sphenooccipital synchondrosis between the three groups. In the CKCS the growth plate closure occurred about the 5th month of life. The second group which was composed of the brachycephalic participants of the study followed next. Finally the synchondrosis sphenooccipitalis ossificated in representatives of mesocephalic breeds around the 13.5th month. However the observation period until the 18th month of life seemed to short. For some participants the sphenooccipital synchondrosis was not closed yet. Therefore it was not possible to make a terminal conclusion on the time of ossification with an observation time of 18 months. However the results confirm the assumption that the premature ossification of the sphenooccipital synchondrosis is the cause of the reduced skull length for brachycephalic breeds. ... With regard to the pathogenesis of the CM the present results support the exceptional position which the CKCS possesses among the brachycephalic breeds. Results of other studies which showed alterations in the basioccipital bone of CKCS suffering from CM are explained. Furthermore current concepts dealing with the development of syringomyelia through disturbances in the venous drainage in the region of the jugular foramen are confirmed. Continuing studies on the sutures of the calvaria are still required to clarify the numerous parameters which contribute to the development of CM in the CKCS." (See also: Comparison of Closure Times for Cranial Base Synchondroses in Mesaticephalic, Brachycephalic, and Cavalier King Charles Spaniel Dogs.)

Pathogenesis and pain in Chiari-like malformation. Peter M. Smith. Vet.J. Dec. 2013;198(3):545-6. Quote: "Chiari-like malformation is now a widely recognised condition affecting several breeds of dog. Most widely characterised in the Cavalier King Charles Spaniel (CKCS), it has since been extensively documented, highlighting the high proportion of the breed that are affected by the condition (Driver et al., 2013). A significant proportion of dogs with Chiarilike malformation also develop syringomyelia, an accumulation of fluid within the spinal cord. This results in various neurological abnormalities, most commonly allodynia (pain caused by a non-noxious stimulus) and dysaesthesia (unpleasant abnormal sensations that can be spontaneous), causing dogs to scratch at the neck. Severe pain develops in some cases and motor deficits are also possible. ... Additional morphological studies, described in detail in the review by Driver et al. (2013), demonstrate the wide array of differences between the bony and vascular structures of the skull and the cervical vertebral column in CKCS and other breeds. The aim of these studies is to establish why the cerebellum protrudes through the foramen magnum, yet it is impossible to know whether these are responsible for the Chiari malformation, or whether they simply reflect coincidental anatomical variation. A similar approach to intervertebral disc disease would have investigators measuring the size of vertebrae in Dachshunds in order to understand what leads to disc extrusion; although intrinsically interesting and valid research, it seems unlikely to generate significant insight into the clinical problem. ... The pathogenesis of syrinx formation in both humans with Chiari malformation type I and in dogs with Chiari-like malformation has been the subject of a large amount of speculation and experimental investigation. This is sensible clinical research; the syrinx appears to be a significant cause of pain and understanding how it forms might help to guide treatments to restrict its development. ... Understanding why the syrinx forms will help to improve surgical treatments and perhaps even lead to strategies aimed at preventing the development of the syrinx in the first place. ... Why, then, does the syrinx not collapse in dogs that undergo decompressive surgery? Perhaps surgery fails to address the key problem in affected dogs. Perhaps surgery fails to address the key problem in affected dogs. ... Although veterinary studies document exploration of the sub-arachnoid space during surgery, it is possible that this is insufficient to fully restore normal CSF flow at the foramen magnum. Of course, it might also reflect the tendency for surgery to be a last resort for dogs, selecting for those that are severely affected or have long-standing problems. There are two therapeutic approaches to dogs with Chiari-like malformation. Treatment with analgesics is generally successful in palliating pain but in those that fail medication, affected dogs are either euthanased, condemned to a life of persistent intractable pain, or offered a surgical treatment that appears not to provide syrinx resolution and has questionable long term benefit. It seems it is now time to divert our attention from simple morphological observations of the CKCS skull to developing a better understanding of the pain suffered by affected dogs. With greater insight into how the syrinx develops, ably documented by Driver et al. (2013), we should not only aim to understand why some dogs that undergo surgery fail to resolve their syrinx, but perhaps also try to pre-empt the development of the syrinx in the first place."

Chiari–like malformation and syringomyelia. Clare Rusbridge. EJCAP, Genetic/Hereditary Disease and Breeding. Oct. 2013;233(3):70-89. Quote: "Syringomyelia is a condition characterised by fluid filled cavities (syrinxes or syringes) within the central spinal cord and the resulting damage produces clinical signs of pain and neurological deficits. Since the increase in availability of magnetic resonance imaging (MRI), syringomyelia is an increasingly common diagnosis in veterinary medicine. The most common cause of syringomyelia in the dog is Chiari-like malformation (Fig 1), a condition analogous to Chiari Type I and 0 malformation in humans. ... Chiari-like malformation and syringomyelia is an inherited disorder with a high morbidity in many brachycephalic toy breeds. It is characterised by overcrowding of the craniocervical junction, obstruction of CSF flow through the foramen magnum and development of fluid filled cavities in the central spinal cord. Although some cases are asymptomatic, dogs with Chiari-like malformation and syringomyelia can present with neurological signs of which the most important is pain. Surgical and medical treatment options are available but these have limited success and from a welfare point of view it would be better to implement a breeding program limiting the occurrence of this disabling disease."

The Effects of Magnetic Resonance Imaging Noise on Cochlear Function in Dogs. Chapter 2 of "Effects of acute and chronic noise exposure on cochlear function and hearing in dogs." Rebecca Elisabeth Venn. MSc(R) thesis pp 21-42, University of Glasgow. 2013. Quote: "In specialised veterinary hospitals, Magnetic Resonance Imaging (MRI) scanners are used daily in diagnostics of dogs. MRI scanners omit high levels of acoustic noise, which is known to be damaging to the hearing of human patients without effective ear protection. However, the effects of the MRI noise levels on the cochlear function and hearing of dogs is often overlooked and in many clinics, dogs are not provided with ear protection for the duration of their scan. The aim of this study was to assess the effects of MRI acoustic noise on the cochlear function of dogs, by Distortion Product Otoacoustic Emissions (DPOAE) testing dogs immediately before and after they underwent an MRI scan. ... Thirty-six dogs were included in the MRI group (mean age 3.9 years, median age 3 years, range 6 months to 10 years; mean bodyweight 16.9 kg, median bodyweight 13.8 kg, range 3.5 kg to 40.8 kg) and 17 dogs were included in the control group (mean age 6.2 years, median age 7 years, range 1 year to 12 years; mean bodyweight 25.1 kg, median bodyweight 23.6 kg, range 6.7 kg to 57.8 kg). There were 16 male dogs in the MRI group (44.4%) and 10 male dogs in the control group (58.8%). A variety of dog breeds were represented, with those represented more than once including three toy poodles, three Lhasa Apso dogs, four Labrador retrievers, two cocker spaniels, four Cavalier King Charles spaniels, two boxers and three cross-breeds in the MRI group, and two Labrador retrievers and two cross-breeds in the control group.... A group of control dogs undergoing a quiet procedure (but treated with the same range of anaesthetic drugs) were also tested. Post-MRI, the mean DPOAE of the dogs was reduced at all frequencies tested, significantly so at five (out of fourteen) frequencies, reflecting a reduction in cochlear function. Furthermore, at all frequencies tested, more than half of the ears exposed to MRI noise demonstrated a decrease in DPOAE. ... The results from this study indicate that exposure to noise during MRI in dogs results in a reduction in cochlear function, which is significant at multiple sound frequencies. ... Without repeat DPOAE testing of the dogs some weeks after their MRI, it is unknown whether this effect is temporary and reversible, or permanent. ... Evidence from human MRI noise exposure would suggest that this effect is temporary. The frequency region affected is likely influenced by the frequency of the noise spectra of the MRI. The demonstration that MRI noise results in some degree of hearing loss, albeit only assessed in the immediate post-MRI period in the present study, would suggest that all dogs having MRI studies performed should have ear protection as a standard precautionary measure."

Evaluation of MR safety of a set of canine ear defenders (MuttMuffs®) at 1 T. Martin A. Baker. Radiography. Nov. 2013;19Mutt Muffs(4):339-342. Quote: "Previous studies have indicated that loud noise produced during MR scanning is hazardous for human patients. Although loud noise can also be harmful to canine patients in MRI, ear protection is not routinely provided. The purpose of this study was to test the safety of a set of commercially available canine ear defenders (MuttMuffs®) during MRI scanning at 1 T. ... The dogs were all of the same breed (Cavalier King Charles Spaniel), with half having been provided with the ear defenders and half which had not. ... A metal fastening ring was removed and replaced with a plastic washer prior to testing. Torque, translation, heating and artifact production were tested. No torque, translation, or excessive heating were detected. No artifacts were observed. Clinical use demonstrated additional benefits of improved immobilisation of the dog, with no effect on signal-to-noise ratio. Results from this study indicate that following replacement of the metal ring with one made of plastic, these canine ear defenders are suitable for use at 1 T. The author recommends the use of ear defenders during canine MRI scans in order to reduce the risk of hearing damage, reduce the dose needed for anaesthetic maintenance and reduce the need for repeated MRI sequences due to movement of the dog."

Comparison of MRI and CT for the detection of cerebellar (foramen magnum) herniation in Cavalier King Charles spaniels. Kromhout K., Bhatti S., Van Ham L., van Bree H., Gielen I. Ghent Univ. Academic Bibliography. 2013. Quote: "Introduction: The Cavalier King Charles spaniel (CKCS) breed exhibits a high rate of Chiari-like malformation (CM). The latter is characterised by a disproportion of volume of the cerebellum and medulla oblongata compared to that of the caudal fossa. These abnormalities are associated with displacement or herniation of the most caudal areas of the cerebellum either into or through the foramen magnum (1,2). Several articles have suggested mid-sagittal magnetic resonance imaging (MRI) as the preferred technique for visualizing the caudal fossa and diagnosing CM (1,3,4). This study compares MRI and computed tomography (CT) for the detection of cerebellar herniation (CH). Materials and Methods: Nine CKCSs were presented with a various range of neurological symptoms. MRI and CT studies of their brains and cranial cervical spines were performed as part of their clinical work-up with the dogs positioned in dorsal recumbency with the head in extended position. Using sagittal T1- and T2-weighted spin echo (T1WSE and T2WSE) MRI sequences and pre- and postcontrast CT-images, the cerebellar herniation length (HL) (= the position of the tip of the cerebellar vermis relative to the foramen magnum) was measured (mm) and assigned either a grade mild (≤ 2mm) or marked (>2mm) by 2 two observers. The results were analyzed statistically. Results: There was a perfect agreement (k=1) for both observers for the detection of mild and marked CH for both techniques. However the Bland-Altman plot analyses of the HL indicated that CT and MRI findings did not agree well. The bias was significantly different from zero when comparing the HL measurements on the CT and MRI images. The limits of agreement for all measurements found the HL differed between techniques over a range of < 1,5 mm. Discussion/ Conclusion: The statistical analysis suggested that both techniques are useful for detecting CH. However because the bias was significantly different from zero, one of the methods consistently led to the determination of longer or shorter HL than the other method. For most comparisons, the HL was on average longer on CT. MRI provides greater soft tissue detail with no beam-hardening artifacts, which may improve the delineation of the cerebellum. Because HL does affect a diagnosis of CM, so CT can be used as a primary diagnostic tool for diagnosing CM in CKCSs when MRI is not available." See also Low-Field MRI and Multislice CT for the Detection of Cerebellar (Foramen Magnum) Herniation in Cavalier King Charles Spaniels.

Prevalence of Chiari-like malformation and Syringomyelia in Cavalier King Charles Spaniels in the Netherlands between 2004 and 2012. W.A. Eggelmeijer. Utrecht University; Nov. 2013. Quote: "Eight hundred and fifteen scans were made of Cavalier King Charles spaniels. ... These 815 scans were made from 732 different CKCS. This means that 83 scans were made from a dog that already had been scanned at least once. Of these dogs the progression over time can be evaluated. ... The 815 scans are made of 732 dogs. Chiari-like malformation is shown in every dog, except for 1 (0,14%). A total of 605 out of 732 dogs had a cerebellum that was misshaped with overcrowding and indentation (82,7%). A total of 126 out of 732 dogs showed clear herniation of the caudal part of the cerebellum (17,2%). In none of the dogs were the tonsils maximally herniated. Syringomyelia is observed in 275 dogs (37,6%) of the 732 dogs. One hundered and sixty four dogs showed a syrinx of more than 2 mm (22,4%) compared to one hundered and eleven dogs with a syrinx less than 2 mm (15,2%). SM was not detected in 457 dogs. (62,4%) Syringomyelia was seen in approximately 37,6% of the dogs with chiari-like malformation. If the dogs had a syrinx of more than 2 mm (164 dogs), 138 dogs had a CM with a cerebellum that was misshaped with overcrowding and indentation (84,1%) versus 26 dogs that showed clear herniation of the caudal part of the cerebellum (15,9%). If the dogs had a syrinx of less than 2 mm (111 dogs), 86 dogs had a CM with a cerebellum that was misshaped with overcrowding and indentation (77,5%) versus 25 dogs that showed clear herniation of the caudal part of the cerebellum (22,5%). ... Conclusion Chiari-like malformation and syringomyelia are a serious problem in the Cavalier King Charles Spaniel. There is a correlation between the prevalence and age of the dogs. This study can not determine the original cause of SM and any influence of CM. More research is necessary to determine the development of SM."

The prevalence of Chiari-like malformation and Syringomyelia in several toy breeds in the Netherlands. P.G.Limburg. Utrecht University; Nov. 2013.

La unión cráneo-cervical: una revisión de las malformaciones de Chiari, bandas durales y la superposición atlanto-occipital. Sofia Cerdá-González, Katherine Bibi. Neuro-Vet. December 2013. 117-128.

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2014

Quantitative Analysis of Chiari-Like Malformation and Syringomyelia in the Griffon Bruxellois Dog. Susan P. Knowler, Angus K. McFadyen, Courtenay Freeman, Marc Kent, Simon R. Platt, Zoha Kibar, Clare Rusbridge. PLOS-One. Feb. 2014. Quote: "This study aimed to develop a system of quantitative analysis of canine Chiari-like malformation and syringomyelia on variable quality MRI. We made a series of measurements from magnetic resonance DICOM images from Griffon Bruxellois dogs with and without Chiari-like malformation and syringomyelia and identified several significant variables. We found that in the Griffon Bruxellois dog, Chiari-like malformation is characterized by an apparent shortening of the entire cranial base and possibly by increased proximity of the atlas to the occiput. As a compensatory change, there appears to be an increased height of the rostral cranial cavity with lengthening of the dorsal cranial vault and considerable reorganization of the brain parenchyma including ventral deviation of the olfactory bulbs and rostral invagination of the cerebellum under the occipital lobes.  ... This study supports the view that CM is a multifactorial condition that includes the shortening of the entire basicranium, loss of convexity of the supraoccipital bone, invagination of the cerebellum under the occipital lobes and possibly by increased proximity of the atlas to the occiput. As a compensatory change, there is increased height of the rostral cranial cavity and lengthening of the dorsal cranial vault. Overcrowding in the caudal cranial fossa and the craniocervical junction is a defining feature. The study provides the basis of a quantitative assessment of CM which might identify risk of syringomyelia and suggests that CM should be redefined so that account is taken of the overcrowding of the entire cranial fossa and craniocervical junction with reorganization of the brain. ... we recommend that this study be repeated and/or modified for other breeds with a high prevalence of CM and syringomyelia such as Cavalier King Charles spaniels and Chihuahuas."

A Cross-Sectional Study of Prevalence and Long-Term Outcome in Symptomatic and Asymptomatic Cavalier King Charles Spaniels with Syringomyelia. M.S. Thofner, A.A. Madry, C.S. Stougaard, C.S. Knudsen, H. Berg, C.S.E. Jensen, R.M.L. Handby, M. Berendt. J.Vet.Int.Med. May 2014;28:944–975. Quote: "The aim of the present study was to investigate the prevalence of SM and long-term outcome in symptomatic and asymptomatic SM-affected Danish Cavalier King Charles Spaniels (CKCS). The study was initiated in 2007 and consisted of three phases. In phase I a cross-sectional study was conducted to estimate the prevalence of SM in dogs older than six years of age where clinical signs are expected to have arisen. The study population consisted of all 240 CKCS born / registered in the Danish Kennel Club in 2001. ... In phase II the association of clinical findings and MRI findings in symptomatic and asymptomatic siblings was investigated. The phase I prevalence study identified several litters with symptomatic and asymptomatic siblings. Eight litters with one or more siblings with clinical signs of SM representing 35 dogs were invited for clinical evaluation and MRI investigation. ... In 2012 a five-year follow-up investigation (phase III) of the litters investigated in phase II was carried out. To assess the long-term outcome in symptomatic and asymptomatic dogs with SM, the owners were contacted by phone. The interview was based on an extensive structured questionnaire addressing the status of the dog including symptomatic / asymptomatic, alive / dead, and cause of dead if not alive. The estimated prevalence of clinically symptomatic syringomyelia in Danish CKCS born in 2001 (> six years of age) was 15.4% (CI95%: 9% - 22%). In study phase II 22 dog owners accepted to let their dog participate in a full clinical work-up including MRI. Thirteen of the 22 dogs (59%) were clinically classified as SM positive whereas the MRI scans revealed a syrinx in the cervical spinal cord in 21 of 22 dogs (95%). No statistical association between clinical signs and the presence of syrinx(es) could be established (p = 0,41). Of the 13 dogs where the owners rejected the MRI examination, five dogs (38%) expressed clinical signs of SM. Ninety-two percent (32/35) of the owners participated in the 2012 follow-up. It was found that after five years (by the age of 11) eleven of the 31 dogs (35%) were alive while 20 (65%) had been euthanized. In four dogs (20%) euthanasia was directly related to severe signs of SM. One dog that was asymptomatic in the phase II investigation in 2007 did develop signs of SM after the age of six. This study found a high prevalence (15.4%) of symptomatic SM in the Danish CKCS population and revealed that despite positive SM findings on MRI, affected dogs may be clinically silent. Asymptomatic dogs may develop clinical signs rather late in life (in this study after the age of six). Despite the high number of affected dogs, euthanasia motivated by SM is relatively moderate. From a clinical point of view our results necessitate further examination of the progression of the disease and assessment of the threshold of outbreak of clinical symptoms."

Syringomyelia in Hong Kong Pet Population: 10-year Data from a Private Veterinary Clinic (2003-2013). S. Guo, D. Lu. J.Vet.Int.Med. May 2014;28:944–975.. Quote: "This retrospective study is the first novel report revealing these facts in a private referral practice in Hong Kong, based on the cases seen from 2003 to 2013. ... A total of 189 cases were included. There were 182 dogs and 7 cats. Of these cases, the distribution is as follows: SMven (SM associated with ventriculomegaly) (61 cases, 32.3%), SMneo (neoplasia) (23 cases, 12.2%), SMivd (intervertebral disc prolapse) (47 cases, 24.9%), SMinf (inflammatory CNS disease) (41 cases, 21.7%), SMtra (trauma) (3 cases, 1.6%), SMmal (malformation) (6 cases, 3.2%), SMfce (fibrocartilaginous embolism) (1 case, 0.5%) and SMund (SM with undetermined cause) (7 cases, 3.7%). The most common breed is Pomeranian (62 cases) followed by Chihuahua (36 cases) and Yorkshire Terrier (20 cases). There are only 4 cases of Cavalier King Charles Spaniel, which is a breed commonly seen with the presence of syringomyelia, indicating a geographical distribution difference of the breeds affected. The SMven cases are likely to be related to Chiari malformation. However, due to the variable skull shapes of the breeds included, further study of the “normal variant” ventricular size in Hong Kong pet population is necessary. In conclusion, MR imaging of the brain should be included as part of the investigation if SM is found in the spinal cord as a large proportion of the spinal SM is associated with ventriculomegaly."

Comparison of MRI and CT for the detection of cerebellar (foramen magnum) herniation in Cavalier King Charles spaniels. Kromhout K., Bhatti S., Van Ham L., van Bree H., Gielen I. Ghent Univ. Academic Bibliography. 2013. Quote: "Introduction: The Cavalier King Charles spaniel (CKCS) breed exhibits a high rate of Chiari-like malformation (CM). The latter is characterised by a disproportion of volume of the cerebellum and medulla oblongata compared to that of the caudal fossa. These abnormalities are associated with displacement or herniation of the most caudal areas of the cerebellum either into or through the foramen magnum (1,2). Several articles have suggested mid-sagittal magnetic resonance imaging (MRI) as the preferred technique for visualizing the caudal fossa and diagnosing CM (1,3,4). This study compares MRI and computed tomography (CT) for the detection of cerebellar herniation (CH). Materials and Methods: Nine CKCSs were presented with a various range of neurological symptoms. MRI and CT studies of their brains and cranial cervical spines were performed as part of their clinical work-up with the dogs positioned in dorsal recumbency with the head in extended position. Using sagittal T1- and T2-weighted spin echo (T1WSE and T2WSE) MRI sequences and pre- and postcontrast CT-images, the cerebellar herniation length (HL) (= the position of the tip of the cerebellar vermis relative to the foramen magnum) was measured (mm) and assigned either a grade mild (≤ 2mm) or marked (>2mm) by 2 two observers. The results were analyzed statistically. Results: There was a perfect agreement (k=1) for both observers for the detection of mild and marked CH for both techniques. However the Bland-Altman plot analyses of the HL indicated that CT and MRI findings did not agree well. The bias was significantly different from zero when comparing the HL measurements on the CT and MRI images. The limits of agreement for all measurements found the HL differed between techniques over a range of < 1,5 mm. Discussion/ Conclusion: The statistical analysis suggested that both techniques are useful for detecting CH. However because the bias was significantly different from zero, one of the methods consistently led to the determination of longer or shorter HL than the other method. For most comparisons, the HL was on average longer on CT. MRI provides greater soft tissue detail with no beam-hardening artifacts, which may improve the delineation of the cerebellum. Because HL does affect a diagnosis of CM, so CT can be used as a primary diagnostic tool for diagnosing CM in CKCSs when MRI is not available." See also Low-Field MRI and Multislice CT for the Detection of Cerebellar (Foramen Magnum) Herniation in Cavalier King Charles Spaniels.

Assoziation zephalometrischer Parameter mit dem Auftreten der Syringomyelie beim Cavalier King Charles Spaniel mit Chiari-ähnlicher Malformation [Association of anatomical parameters with the occurrence of syringomyelia in the Cavalier King Charles Spaniel with Chiari malformation]. Annabell Johanna Grübmeyer. Giessener Elektronische Bibliothek. Jan. 2014. Quote: "Until now the Chiari-like malformation was only diagnosed in brachycephalic dog breeds. Based on the decreased length-breadth ratio of its skull the Cavalier King Charles Spaniel can be classified as a highly brachycephalic dog. Therefore it could be assumed that the grade of brachycephaly is a pathophysiological factor for the development of syringomyelia and a retarded length growth of the skull might be the cause for the changes found in the Chiari-like malformation. The question is, if a shortening of the cranial base gives rise to the pathological changes in Chiari-like malformation. Based on this question we examined the anatomical parameters of 107 Cavalier King Charles Spaniels in relationship to the occurrence of syringomyelia. The study should give information about the pathogenesis of the Chiari-like malformation and the development of syringomyelia and if there is a difference in the cranial base length in Cavalier King Charles Spaniels with or without syringomyelia. The 107 Cavalier King Charles Spaniels examined in this study were mostly presented for breeding examinations, but some were also presented because of clinical signs. The age of the examined dogs ranged from 6 month to 9 years. We performed computed tomography of the skull and magnetic resonance imaging of the skull and spine of all patients. The examination of the spine in patients introduced for breeding examinations, were performed until the 5th cervical vertebra. In patients with neurological signs the examination included also the caudal cervical, thoracic and lumbar spine. Changes consistent with the Chiari-like malformation were found in all 107 Cavalier King Charles Spaniels. 63 of the 107 dogs showed a syringomyelia at the point of examination. The results of the study showed that the incidence of syringomyelia is correlated to the variables age (p less than 0,007), SBI [skull base index] (p less than 0,0192), PI [presphenoid index] (p less than 0,0447) and BI [basisphenoid index]  (p less than 0,0206). Furthermore it is shown that Cavalier King Charles Spaniels with a decrease in SBI have an increased risk to develop syringomyelia (odds ratio 1,26). In addition also the presphenoid and the basioccipital bone showed a reduced length, with an increase in breadth in dogs with syringomyelia. This study showed, that a reduced length of the cranial base represents a risk factor for the occurrence of syringomyelia. These results support the assumption of other authors that the cause of the Chiari-like malformation and syringomyelia is up to a growth disturbance of the cranial base."

Zur Okzipitalen Dysplasie des Foramen magnum und Morphometrie des Atlas beim Hund. Eine computertomographische Studie. [The occipital dysplasia of the Foramen magnum and the morphometry of the atlas in dogs. A computer tomographic study.] Iris Spörl. Ludwig-Maximilians-University Munich.  Quote: "Aim of this study is a computer tomographic representation of the differences in the morphometry of the foramen magnum and the atlas in dogs. Dogs included in the study were divided into three groups: neurologically healthy toy breed dogs (group 1), dogs with atlanto-axial instability (group 2) and large breed dogs. Occipital dysplasia is defined as a varying dorsal notch of the foramen magnum in toy breed dogs. Degree of dysplasia, the dorsal notch index, the occipital index and the foramen magnum index were being calculated and all four of them showed significant differences in those three groups. Large breed dogs showed a normal transverse ovoid shape without a dorsal notch. Neurologically healthy toy breed dogs had a relatively wide foramen magnum with a dorsal notch and a big variety of shapes. In comparison to former studies based on toy breed sculls the results were similar, whereas radiological examinations showed lower values. Both dogs with an AaI and neurologically healthy toy breed dogs had a wider foramen magnum, which is more distinct in the latter. In the transversal plane of the atlas the vertebral chanal has been measured and classified in vertically oval-round and cross-oval. In the sagittal plane the relation of the atlas´ inside diameter and the dorsal arch´s length has been calculated and thus the ratio has been determined. The side ratio could be greater than 1 or less than or equal to 1. Large breed dogs with a vertically oval-round vertebral chanal had a side ratio equal to 1 which is physiological. The side ratio in healthy toy breed dogs and dogs with AaI was greater than 1, which means, that this too is a morphological variation in toy breed dogs. The vertebral chanal in those two groups was cross ovoid."

Quantitative Trait Loci (QTL) Study Identifies Novel Genomic Regions Associated to Chiari-Like Malformation in Griffon Bruxellois Dogs. Philippe Lemay, Susan P. Knowler, Samir Bouasker, Yohann Nédélec, Simon Platt, Courtenay Freeman, Georgina Child, Luis B. Barreiro, Guy A. Rouleau, Clare Rusbridge, Zoha Kibar. PLOS One. April 2014. Quote: "Chiari-like malformation (CM) is a developmental abnormality of the craniocervical junction that is common in the Griffon Bruxellois (GB) breed with an estimated prevalence of 65%. This disease is characterized by overcrowding of the neural parenchyma at the craniocervical junction and disturbance of cerebrospinal fluid (CSF) flow. The most common clinical sign is pain either as a direct consequence of CM or neuropathic pain as a consequence of secondary syringomyelia. The etiology of CM remains unknown but genetic factors play an important role. To investigate the genetic complexity of the disease, a quantitative trait locus (QTL) approach was adopted. A total of 14 quantitative skull and atlas measurements were taken and were tested for association to CM. Six traits were found to be associated to CM and were subjected to a whole-genome association study using the Illumina canine high density bead chip in 74 GB dogs (50 affected and 24 controls). Linear and mixed regression analyses identified associated single nucleotide polymorphisms (SNPs) on 5 Canis Familiaris Autosomes (CFAs): CFA2, CFA9, CFA12, CFA14 and CFA24. A reconstructed haplotype of 0.53 Mb on CFA2 strongly associated to the height of the cranial fossa (diameter F) and an haplotype of 2.5 Mb on CFA14 associated to both the height of the rostral part of the caudal cranial fossa (AE) and the height of the brain (FG) were significantly associated to CM after 10 000 permutations strengthening their candidacy for this disease (P = 0.0421, P = 0.0094 respectively). The CFA2 QTL harbours the Sall-1 gene which is an excellent candidate since its orthologue in humans is mutated in Townes-Brocks syndrome which has previously been associated to Chiari malformation I. Our study demonstrates the implication of multiple traits in the etiology of CM and has successfully identified two new QTL associated to CM and a potential candidate gene."

Intermittent Pain & Scratching in a Cavalier King Charles Spaniel. Megan Stout Steele, Jonathan Levine. Clinicians Brief. May 2014. Quote: "Lucy, a 7-year-old spayed Cavalier King Charles spaniel, was presented for chronic intermittent cervical pain and scratching of the head and neck. History: ... Lucy had a 2- to 3-year history of intermittent episodes of vocalization and reluctance to be touched around the head and neck. In addition, the dog frequently attempted to scratch her head, neck, muzzle, and ears, although rarely did the paws come into contact with the skin surface. During the past year, the dog had progressive difficulty using her pelvic limbs on slippery surfaces. The owners also suspected some hearing loss. Examination: ... Bilateral mild ceruminous otic debris was noted. The dog’s mentation appeared normal and no cranial nerve deficits were noted; however, response to auditory stimuli was absent bilaterally. On gait analysis, mild generalized proprioceptive ataxia, cerebellar ataxia, and tetraparesis were noted. Myotatic reflexes were increased in the pelvic limbs, and thoracic limb flexor withdrawal reflexes were diminished bilaterally. Cervical pain and phantom scratching were elicited during vertebral column palpation. Lesions were localized to the C6-T2 spinal cord segments, cerebellum, and auditory apparatus. Diagnostics: CBC, serum chemistry panel, and urinalysis results were within reference ranges. Three-view thoracic radiographs showed no abnormalities. MRI of the brain and cranial cervical vertebral column showed cerebellar compression and coning secondary to the malformed caudal occipital bone, with lack of normal cerebrospinal fluid (CSF) surrounding the caudal cerebellum. A T2 hyperintense–T1 hypointense lesion within the spinal cord parenchyma from the level of C1 caudally was noted. The tympanic bullae contained T2-hyperintense and T1-isointense material. No contrast enhancement was identified. Diagnosis: Chiari-like malformation (CLM) and syringohydromyelia (SHM); bilateral primary secretory otitis media (PSOM). Treatment: Lucy was admitted for additional diagnostic testing and treatment and underwent myringotomy and bilateral deep ear flushing. Large, clear mucus plugs were removed from both middle ears; culture of the plugs was negative for bacteria. These findings and the MRI results were most consistent with PSOM. The patient recovered well from anesthesia and the next day was reanesthetized for foramen magnum decompression and C1 dorsal laminectomy with durotomy. Surgical recovery was uncomplicated. After 3 days, the patient was discharged with pregabalin at 2 mg/kg PO q12h for neuropathic pain associated with SHM, omeprazole at 1 mg/kg PO q24h to decrease CSF production, and tramadol at 4 mg/kg PO q8h for 5 days to address temporary soft tissue pain. In addition, N-acetylcysteine at 600 mg PO q24h was prescribed as a mucolytic to lower the risk for PSOM recurrence. Outcome: At the 1-month reevaluation, the dog’s hearing seemed to have improved, but her gait abnormalities and phantom scratching persisted."

Comparison of the endocranial- and brain volumes in brachycephalic dogs, mesaticephalic dogs and Cavalier King Charles spaniels in relation to their body weight. Martin J Schmidt, Kerstin H Amort, Klaus Failing, Melanie Klingler, Martin Kramer and Nele Ondreka. Acta Veterinaria Scandinavica. May 2014;56:30. Quote: "Background: A number of studies have attempted to quantify the relative volumes of the endocranial volume and brain parenchyma in association with the pathogenesis of the Chiari-like malformation (CLM) in the Cavalier King Charles spaniel (CKCS). In our study we examine the influence of allometric scaling of the brain and cranial cavity volume on morphological parameters in different dog breeds. MRI scans of 110 dogs (35 mesaticephalic dogs, 35 brachycephalic dogs, 20 CKCSs with SM, and 20 CKCSs without SM) have been used to create 3-dimensional volumetric models of skull and brain parts. Volumes were related to body weight calculating the adjusted means for different breeds. Results: There was a strong global dependency of all volumes to body weight (P < 0.0001). The adjusted means of the absolute and relative volumes of brain parenchyma and cranial compartments are not significantly larger in CKCSs in comparison to brachycephalic and mesaticephalic dogs. A difference in absolute or relative volumes between CKCSs with and without SM after relating these values to body weight could not be identified. The relative volume of the hindbrain parenchyma (caudal fossa parenchyma percentage) was larger in brachycephalic dogs than in CKCSs, without causing herniation or SM. Conclusion: An influence of body weight exist in dogs, which can be sufficiently large to render conclusions on the difference in volumes of the brain and skull unsafe unless some account of the body weight is taken in the analysis. The results of this study challenge the role of overcrowding for the development of SM in dogs."

Relationship of dorsal atlantoaxial junction compressive lesions (dural bands) to clinical signs and syringomyelia in cavalier king charles spaniels. S. Cerda-Gonzalez, N.J. Olby, E.H. Griffith. J.Vet.Int.Med. July 2014;28(4):1357. Quote: "Dorsal compressive lesions at the atlantoaxial junction (i.e. dural bands) are a well-recognized craniocervical junction anomaly, frequently seen alongside other craniocervical junction anomalies such as Chiari-like malformations. Despite their regular identification on imaging, their clinical significance remains unclear. To address this, the authors investigated their influence on clinical status and on syringomyelia in a commonly affected breed. Thirty-six Cavalier King Charles spaniels (CKCS) were assessed for neuropathic pain and neurologic dysfunction, and were assigned a neurologic grade. Magnetic resonance imaging of the craniocervical junction was performed, with the head and neck straight and flexed. Imaging studies were then assessed for a dural band, a Chiari-like malformation (CM), and syringomyelia. Dural band and syringomyelia severity was determined using both a compression index (objective) and grading (subjective), respectively. Of the 36 CKCS imaged, 20 demonstrated neuropathic pain. Dural bands were present in 31/36 (83.8%) dogs; 34 had a CM. Syringomyelia was found in 23 (56.8%) dogs, 21 of which also had a dural band. Dural bands were associated with both the presence and severity of clinical signs, and the presence of syringomyelia. Higher compression indices were associated with more severe syringomyelia."

Magnetic resonance imaging signs of presumed elevated intracranial pressure in dogs. S. Bittermann, J. Lang, D. Henke, J. Howard, D. Gorgas. Vet.J. July 2014;201(1):101-108. Quote: "The aim of this study was to describe magnetic resonance imaging (MRI) findings associated with presumed elevated intracranial pressure (ICP) in dogs and to evaluate whether MRI could be used to discriminate between dogs with and without elevated ICP. Of 91 dogs that underwent cranial MRI examination, 18 (19.8%) were diagnosed with elevated ICP based on neurological examination, fundoscopy and transcranial Doppler ultrasonography. The MRI findings that showed the strongest association with elevated ICP were mass effect (odds ratio [OR], 78.5), caudal transtentorial herniation (OR, 72.0), subfalcine herniation (OR, 45.6), perilesional oedema (OR, 34.0), displacement of the lamina quadrigemina (OR, 27.7) and effacement of the cerebral sulci (OR, 27.1). The presence of any two or more of the following MRI findings identified elevated ICP with a sensitivity of 72% and a specificity of 96%: compression of the suprapineal recess, compression of the third ventricle, compression of the fourth ventricle, effacement of the cerebral sulci and caudal transposition of the lamina quadrigemina. In conclusion, there is an association between MRI findings and elevated ICP in dogs; therefore, MRI might be useful to discriminate between dogs with and without elevated ICP."

Syringomyelia: determining risk and protective factors in the conformation of the Cavalier King Charles Spaniel dog. Measuring CKCS's cephalic indexThomas J. Mitchell, Susan P. Knowler, Henny van den Berg, Jane Sykes, Clare Rusbridge. Canine Genetics & Epidemiology. July 2014. Quote: "Syringomyelia (SM) is a painful condition, more common in toy breeds, including the Cavalier King Charles Spaniel (CKCS), than other breeds. In these toy breeds, SM is usually secondary to a specific malformation of the skull (called Chiari-like Malformation, CM for short). There has been debate as to whether head shape is related to CM/SM, especially as some humans have similar characteristic facial and skull shapes, and what this may be. Identifying a head shape in dogs that is associated with these diseases would allow for selection away from these conditions and could be used to further breeding guidelines. 133 dogs were measured in several countries using a standardised 'bony landmark' measuring system and photo analysis by trained researchers. This paper describes two significant risk factors associated with CM/SM in the skull shape of the CKCS: extent of brachycephaly (the broadness of the cranium (top of skull) relative to its length) and distribution of doming of the cranium. The study showed that having a decreased cephalic index (less brachycephaly) was significantly protective. Further to this, more cranium at the back of the head (caudally) relative to the amount at the front of the head (rostrally) was significantly protective against disease development. This was shown at three and five years of age, and also when comparing a sample of “SM clear” individuals over five years to those affected under three years. This study suggests that brachycephaly, with resulting rostrocaudal doming, is associated with CM/SM. These results could provide a way for selection against the risk head shape in the CKCS, and thus enable a reduction in CM/SM incidence. Studying other breeds in which CM free individuals are more frequent may validate this risk phenotype for CM too."

Micronized/ultramicronized palmitoylethanolamide displays superior oral efficacy compared to nonmicronized palmitoylethanolamide in a rat model of inflammatory pain. Daniela Impellizzeri, Giuseppe Bruschetta, Marika Cordaro, Rosalia Crupi, Rosalba Siracusa, Emanuela Esposito, Salvatore Cuzzocrea. Neuroinflammation. August 2014; doi: 10.1186/s12974-014-0136-0. Quote: Background: The fatty acid amide palmitoylethanolamide (PEA) has been studied extensively for its anti-inflammatory and neuroprotective actions. The lipidic nature and large particle size of PEA in the native state may limit its solubility and bioavailability when given orally, however. Micronized formulations of a drug enhance its rate of dissolution and reduce variability of absorption when orally administered. The present study was thus designed to evaluate the oral anti-inflammatory efficacy of micronized/ultramicronized versus nonmicronized PEA formulations. Methods: Micronized/ultramicronized PEA was produced by the air-jet milling technique, and the various PEA preparations were subjected to physicochemical characterization to determine particle size distribution and purity. Each PEA formulation was then assessed for its anti-inflammatory effects when given orally in the carrageenan-induced rat paw model of inflammation, a well-established paradigm of edema formation and thermal hyperalgesia. Results: Intraplantar injection of carrageenan into the right hind paw led to a marked accumulation of infiltrating inflammatory cells and increased myeloperoxidase activity. Both parameters were significantly decreased by orally given micronized PEA (PEA-m; 10 mg/kg) or ultramicronized PEA (PEA-um; 10 mg/kg), but not nonmicronized PeaPure (10 mg/kg). Further, carrageenan-induced paw edema and thermal hyperalgesia were markedly and significantly reduced by oral treatment with micronized PEA-m and ultramicronized PEA-um at each time point compared to nonmicronized PeaPure. However, when given by the intraperitoneal route, all PEA formulations proved effective. Conclusions: These findings illustrate the superior anti-inflammatory action exerted by orally administered, micronized PEA-m and ultramicronized PEA-um, versus that of nonmicronized PeaPure, in the rat paw carrageenan model of inflammatory pain.

Chiari-Like Malformation and Syringomyelia in American Brussels Griffon Dogs. A.C. Freeman, S.R. Platt, M. Kent, E. Huguet, C. Rusbridge, S. Holmes. J.Vet.Int.Med.; Sept. 2014;28(5):1551-1559. Quote: "Background: Although Chiari-like malformation (CM) and syringomyelia (SM) have been described in many small breed dogs, the prevalence and clinical manifestations of this complex have not been documented in a large cohort of American Brussels Griffon (ABG) dogs. Objectives: To characterize the clinical and magnetic resonance imaging (MRI) features of CM and SM in the ABG breed. Animals: Eighty-four American Kennel Club registered ABG dogs were recruited. Methods: Prospective study. Complete histories and neurologic examinations were obtained before MRI. Images were blindly reviewed and calculations were made by using OsiriX. All analyses were performed by Student's t-test, Spearman's correlation, ANOVA, and chi-square test where appropriate. Results: Chiari-like malformation and SM were present in 65% and 52% of dogs, respectively. Twenty-eight percent of dogs had neurologic deficits and 20% had neck pain. Mean central canal (CC) transverse height was 2.5 mm with a mean length of 3.6 cervical vertebrae. Neurologic deficits were significantly associated with a larger syrinx (P = .04, P = .08) and syrinx size increased with age (P = .027). SM was associated with a smaller craniocervical junction (CCJ) height (P = .04) and larger ventricles (P = .0001; P < .001). Conclusions and Clinical Importance: Syringomyelia and CM are prevalent in American Brussels Griffon dogs. Syrinx size is associated with neurologic deficits, CM, larger ventricles, a smaller craniocervical junction height, neurologic deficits, and cerebellar herniation. Fifty-two percent of dogs with a SM were clinically normal."

Syringomyelia in cavalier King Charles spaniels and the incidence in South Africa. A. J. Carter. WSAVA Congress 2014. Sept. 2014. Proceedings Book pp. 32-35. Quote: "Syringomyelia is highly prevalent within the South African Cavalier King Charles Spaniels. I have been involved in a screening program with the CKCS breeders and to date we have screened about 85 dogs and this process is ongoing at the moment. The prevalence of syringomyelia in CKCS in South Africa is 41%. The grading system provides information for the breeders with regards to selecting dogs for breeding and reducing the incidence of syringomyelia. The major short fall of the grading system (2006 grading system) is that it relies on the breeder to declare any clinical signs that are evident in their dogs that are noticed in the home environment as the clinical signs are often subtle and not evident in the consulting room. This makes differentiation between the grading of D and E from F dependant on the breeder which is critical to the breeding program and if the breeder wants to conceal the clinical symptoms the eradication of the problem will be hindered. The 2012 grading scheme is more simplified and does away with clinical signs as part of the grading criteria except to say that if clinical signs are evident then dogs should not be used for breeding. The CKCS also suffers from hereditary mitral valve disease and this needs to be screened at the same time as syringomyelia screaming. If the breeders are to reduce the incidence of the condition then strict screening and breeding programs will need to be implemented."

Association between the findings on magnetic resonance imaging screening for syringomyelia in asymptomatic cavalier king charles spaniels and observation of clinical signs consistent with syringomyelia in later life. E.J. Ives, L. Doyle, M. Holmes, T.L. Williams, A.E. Vanhaesebrouck. Vet.J. January 2015;203(1):129-130. Quote: "The likelihood of an asymptomatic dog developing clinical syringomyelia in later life is unknown. Association of magnetic resonance imaging findings in asymptomatic dogs and clinical signs in later life was investigated. A questionnaire based study was used to investigate the association between the findings on magnetic resonance imaging (MRI) screening for syringomyelia (SM) in 79 asymptomatic Cavalier King Charles spaniels (CKCS) and the subsequent development of clinical signs consistent with SM in later life. Owners reported clinical signs consistent with SM in 13/79 (16%) dogs at the time of the questionnaire. Asymptomatic dogs with a syrinx appear more likely to display clinical signs than those without. A significantly greater proportion of CKCS with a syrinx visible on MRI screening showed clinical signs in later life (9/25, 36%) than dogs without a visible syrinx (4/54, 7%; odds ratio 6.9). Whether the findings of MRI screening can be used to indicate the likelihood of an asymptomatic CKCS developing clinical signs consistent with SM in later life warrants further prospective study in a larger cohort of dogs.

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2015

Prevalence and Heritability of Symptomatic Syringomyelia in Cavalier King Charles Spaniels and Long-term Outcome in Symptomatic and Asymptomatic Littermates. M.S. Thøfner, C.L. Stougaard, U. Westrup, A.A. Madry, C.S. Knudsen, H. Berg, C.S.E. Jensen, R.M.L. Handby, H. Gredal, M. Fredholm, M. Berendt. J.Vet.Internal Medicine. January 2015;29(1):243-250. Quote: "Background: Syringomyelia (SM) is common in the Cavalier King Charles Spaniel (CKCS). Dogs with syrinxes express clinical signs or might be clinically silent. Objectives: To investigate the prevalence and heritability of symptomatic SM, the association between clinical signs and magnetic resonance imaging (MRI) findings, and long-term outcome. Animals: All CKCS registered in the Danish Kennel Club in 2001 (n = 240). Methods: A cross-sectional questionnaire-based prevalence study validated by telephone interviews and clinically investigated clinical signs of SM. Dogs were 6 years at the time of investigation. A prospective observational litter study including clinical investi-gations, MRI and 5-year follow-up of symptomatic and asymptomatic siblings. Heritability was estimated based on the scale of liability in the study population and litter cohort. Results: The cross-sectional study estimated a prevalence of symptomatic SM at 15.4% in the population. Thirteen symptomatic and 9 asymptomatic siblings participated in the litter study. Spinal cord syrinxes were confirmed in 21 of 22 littermates (95%). Syrinx diameter and mean syrinx : spinal cord ratio were significantly correlated with clinical signs (P < .01). Estimated heritability of symptomatic SM was 0.81. Symptomatic SM motivated euthanasia in 20%. Dogs with syrinxes, which expressed no clinical signs at the age of 6, remained asymptomatic in 14/15 cases (93%). Conclusions and Clinical Importance: The prevalence of symptomatic SM is high and genetics have a high impact on clinical disease expression. Further investigations of factors influencing the outbreak threshold of clinical signs of SM are desirable." See ECVN/ESVN 26th Symposium abstract above.

Prevalence of Chiari-like Malformations in Clinically Unaffected Dogs. T.R. Harcourt-Brown, J. Campbell, C. Warren-Smith, N.D. Jeffery, N.P. Granger. J.Vet. Internal Medicine. January 2015;29(1):231-237. Quote: "Background: The importance of Chiari-like malformation (CM) in the generation of clinical signs or the formation of syringomyelia in dogs is incompletely understood, partly because the prevalence of various CM definitions in unaffected dogs is unknown. Hypothesis/ Objectives: The aims were: to estimate the prevalence of CM in dogs asymptomatic for CM or syringomyelia, according to 3 currently used definitions [Definitions: 1. Indentation: indentation of the caudal aspect of the cerebellum —- defined as a concave, rather than flattened or convex, caudal border of the cerebellum. 2. Impaction: impaction of the cerebellar vermis into the foramen magnum -— defined as deformation of the shape of caudo-ventral vermis into a point such that the angle between lines drawn along the caudal and ventral borders of the cerebellum meet at an acute, rather than an obtuse, angle. This definition was considered analogous to descent into the foramen magnum that has been used previously. 3. Herniation: herniation of the cerebellar vermis through the foramen magnum -— defined as extension of the cerebellar vermis caudal to a line drawn between the ventral aspect of the supraoccipital bone (opisthion) and the caudal border of the basioccipital bone (basion) -- our primary aim was to establish the prevalence of CM in non-CKCS dogs]; and, to investigate the effect of brachycephaly and head position during magnetic resonance (MR) imaging on estimates of the prevalence of CM. Animals: 199 client-owned dogs without apparent signs of CM or syringomyelia [14 cavalier King Charles spaniels (CKCS); 12 Staffordshire bull terriers; 12 Jack Russell terriers; 11 Cocker spaniels; 22 Labrador retrievers; 14 Springer spaniels; 11 golden retrievers]. Methods: Archived MR images were analyzed for evidence of cerebellar indentation and impaction into or herniation through the foramen magnum. Logistic regression analysis was used to investigate the relationship of CM diagnosis with head position and the cranial index (a measure of brachycephaly). Results: In 185 non-CKCS dogs, indentation was identified in 44% (95% CI, 47–51%) and impaction in 22% (95% CI, 16–28%). No non-CKCS dogs showed herniation; [100% of CKCSs had indentation, 86% showed impaction, and 29% of CKCSs showed herniation (11–55%)]. Regression analysis showed a significant increase in the odds of indentation and impaction in an extended head position and as the cranial index increased (became more brachycephalic). Conclusions and Clinical Importance: We conclude there is a high prevalence of cerebellar indentation and impaction in the normal canine population, suggesting they are unreliable as defining factors for CM. Our data supported the hypothesis that some measures of brachycephaly are associated with indentation or impaction, but the overlap in these measurements among breeds showed that construction of control groups based on subjective assessment of skull type could be inappropriate. Instead, it may be better for future studies investigating the relationship between abnormalities of the caudal cranial fossa and clinical signs or syringomyelia to define control groups based on the absence of specific anatomical features considered important (eg, cerebellar herniation, obstruction to CSF flow at the foramen magnum)."

Low-Field MRI and Multislice CT for the Detection of Cerebellar (Foramen Magnum) Herniation in Cavalier King Charles Spaniels. K. Kromhout, H. van Bree, B.J.G. Broeckx, S. Bhatti, L. Van Ham, I. Polis, I. Gielen. J. Vet. Int. Med. January 2015;29(1):238-242. Quote: "Background: Cavalier King Charles Spaniels (CKCS) have a high prevalence of Chiari-like malformation (CM). Herniation of the cerebellum into the foramen magnum is a key diagnostic feature for CM. Midsagittal MR images are the preferred technique for visualizing cerebellar herniation (CH). Objective: To investigate whether CT can be used to diagnose CH. Animals: Fifteen client-owned CKCS dogs referred for investigation of the brain and cranial cervical spine on MRI and CT. Methods: Two reviewers retrospectively analyzed midsagittal T1WSE and T2WSE MR images and midsagittal pre- and postcontrast 2D multiplanar reformatted CT images from each dog for the presence of CH. And, if present, the length (mm, CHL) of the herniation was measured. The results were analyzed statistically. Results: There was no significant difference between the different observers and techniques for the detection of CH and measurement of CHL. Overall, the CHL was longer on the CT images. Conclusion and Clinical Importance: Both techniques are useful for detecting CH and measuring CHL. Because CHL does not have a known direct impact on the clinical presentation of CM, CT can be used as a diagnostic tool in a routine clinical practice for CM in CKCS when MRI is not available. We emphasize that MRI is the standard screening technique in CKCS for breeding purposes to detect the presence of CM and SM and, at the current time, CT cannot replace MRI." See also, Comparison of MRI and CT for the detection of cerebellar (foramen magnum) herniation in Cavalier King Charles spaniels.

Dilemma in the diversity of foramen magnum dimensions. David Kilroy, Arun Kumar. BEMS Reports. Jan. 2015;1(1):3-6. Quote: "Foramen magnum, which is an opening for the passage of spinal cord is highly variable in its dimensions, the reasons for which are not known. In this report we examined a few skulls from different species and performed selective morphometric analysis (Condyle ratio, Nuchal ratio and radius) to derive possible explanations for variations in size of foramen magnum. ... Non-invasive determination of foramen magnum diameter may also have utility in prediction of individuals prone for herniation of the cerebellum, especially in species, which are predisposed to this condition. For instance Cavalier King Charles Spaniels have high predisposition toherniation of the cerebellum into the foramen magnum. Hence it will be interesting to evaluate if radius analysis of foramen magnum diameter and its symmetry would be of help to identify individual dogs prone for herniation of the cerebellum. ... We propose possible influence of variations in dimension of foramen magnum on a few physio-anatomical traits, which necessitates further research."

Foramen magnum decompression surgery in 23 Chiari-like malformation patients 2007-2010: Outcomes and owner survey results. Ortinau N, Vitale S, Akin EY, Beasley M, Shores A. Canadian Vet. J. March 2015;56(3):288-291. Quote: "Chiari-like malformation (CLM) with syringomyelia (SM) in dogs is particularly prominent in the Cavalier King Charles spaniel breed, but has also been reported in several other small breed dogs. ... Dogs were considered surgical candidates if they met all the criteria shown [below] and received oral medications [gabapentin, 5 mg/kg body weight (BW), q8h, and omeprazole, 1 mg/kg BW, q24h] for 2 wk prior to surgery: 1. MRI evidence of Chiari-like malformation and cervical syringomyelia; 2. Syrinx in the cervical spinal cord measuring ≥3mm diameter on transverse T2 MRI; 3. Clinical signs of phantom scratching, cervical pain or hypersensitivity, or thoracic limb paresis without MRI/CSF evidence of other changes that could produce the same clinical signs. ... These criteria were based on clinical impressions from examination and treatment of CLM-SM patients over several years and remain unproven. Severely affected patients with syrinxes <3mm in diameter that respond poorly to medical management might also benefit from surgery. ... Over a period of 3 years, 23 canine patients [including 18 CKCSs] were treated surgically for CLM-SM. Surgery consisted of foramen magnum decompression, durotomy, duraplasty, and free autogenous adipose tissue grafting (fat graft). All patients were re-evaluated clinically at least 1 month after surgery and some up to 3 years after surgery. Improvement was noted on all clinical evaluations. A questionnaire was mailed to all 23 owners after a period of at least 1 year after surgery. Seventeen surveys were returned. No patient has required additional surgery to date, 94% (16/17) had some improvement in quality of life after surgery, and none were judged to deteriorate to less than the pre-surgical status. The authors conclude that this surgical procedure, combined with medical therapy, resulted in favorable long-term outcomes."

“Under the weather?” Comparing barometric pressure with clinical signs of Chiari malformation and syringomyelia in Cavalier King Charles Spaniels. William Warman, Edward Ives, Clare Rusbridge. BSAVA Conf. April 2015. Abstract Pg. 444. Quote: “Anecdotally, changes in barometric pressure can lead to changes in degrees of discomfort for dogs affected by Chiari Malformation and Syringomyelia (CM/SM). This prospective, blinded study aimed to determine whether correlation exists between changes in local barometric pressure and the ownerperceived comfort of Cavalier King Charles Spaniels (CKCS) with CM/SM. Such data could allow alteration of medications to reduce episode severity during barometric pressure changes, or the development of a weather warning system to predict exacerbation of clinical signs before this occurs. Owners of CKCS with CM/SM were requested to complete questionnaires providing background information and daily comfort grading scores for their dogs. Daily comfort grading score and change in comfort score between days were compared to local mean daily barometric pressure and pressure changes both during and between days from Meteorological Office data over a 3 month period. Questionnaires for 22 dogs were analysed, producing 1826 data points. Reported changes from baseline medication were adjusted for in the statistical analysis. No correlation between mean daily barometric pressure and daily comfort grading score was found (spearman’s rho = 0.03, P = 0.23). A significant but weak negative correlation between change in mean daily pressure and change in comfort score between days was observed following adjustment for changes in medication (r = 0.05, P = 0.026). No correlation was found between absolute pressure change and change in comfort score or between absolute pressure change and absolute change in comfort score. Currently, there is no evidence supporting an association between barometric pressure and the degree of discomfort experienced by CKCS with CM/SM. This appears contrary to the experience of some individuals affected by these conditions. A more objective assessment of a larger population of dogs is required to determine whether or not barometric pressure has an influence on the comfort of some or all CKCS with CM/SM. A further study by the same authors is in development, aiming to investigate whether there is an association between barometric pressure and comfort scores in people affected by CM/SM. A larger sample size will be sought, allowing more powerful statistical analysis of the results. This canine study has functioned as a useful guide to methods of data collection and analysis that can be used in future canine and human studies on this subject.”

Prevalence and management of canine Chiari-like malformation/syringomyelia recorded in primary-care practice in England. Claire Thomas, Sandra Sanchis-Mora, Ludovic Pelligand, Holger Volk, David Church, Paul McGreevy, Peter Thomson, Dave Brodbelt, Dan O’Neill. BSAVA Conf. April 2015. Abstract Pg. 446. Quote: “Chiari-like malformation / syringomyelia (CM/SM) describes a developmental disorder that can cause pain and reduce quality of life. This study aimed to explore clinical CM/SM cases in the veterinary primary-care setting in order to improve our understanding of the impact of the disorder on the overall canine population. The study included clinical data on all dogs shared with the VetCompass primary-care project from 01/09/2009 to 13/06/2014. The case definition required a clinical diagnosis with CM/SM confirmed using magnetic resonance imaging (MRI) in a clinically affected dog. Possible cases were sourced from the free text and VeNom diagnoses using key-search terms. Following manual verification, additional information was extracted regarding clinical signs and therapeutic management. Descriptive statistics were used to report CM/SM prevalence, demography, clinical signs and therapy. A total of 59 CM/SM cases were identified from 187,365 dogs, giving a prevalence of 0.03% (95% confidence interval (CI): 0.02–0.04) across all dogs. The median (interquartile range) age at diagnosis was 4.33 (0.33–11.58) years for the 34 incident cases (57.62%). The most commonly affected breedtypes were Cavalier King Charles Spaniel (CKCS) (37 dogs; 62.71%), King Charles Spaniels (12 dogs, 20.33%), crossbreed (3 dogs, 5.08.%), Yorkshire Terrier (2 dogs, 3.38%), and Affenpinscher, Pug, English Toy Spaniel, Jack Russell Terrier and Chihuahua (1 dog, 1.69%). From the VetCompass population of 3,860 CKCSs, this gave a breed prevalence of 0.96% (95% CI: 0.69–1.34) of MRI confirmed cases. Practitioners also reported an additional 84 CKCS (2.18%, 95% CI: 1.75–2.70) suspected but unconfirmed cases. The most common clinical signs associated with CM/SM were expression of pain (14 dogs, 23.72%), characteristic CM/SM-associated motor signs (scratching or facial rubbing without underlying skin disease) (11 dogs, 18.64%) and ataxia or weakness (7 dogs, 11.86%). Clinical signs were not specified for 16 cases (27.11%). Analgesics (alone or in combination) were prescribed to 49 cases (83%). The most common analgesic treatments were gabapentin (32 dogs, 65.3%), NSAIDs (18 dogs, 36.7%), glucocorticoids (30 dogs, 26.3%) and tramadol (13 dogs, 26.5%). Practitioners reported 31 dogs (63.26%) showed apparent clinical improvement following treatment. This study reported a low overall prevalence of clinical CM/SM but higher prevalence in some individual breeds. The high proportion of affected animals with clinical signs that can variably reduce quality of life and that required analgesic therapy highlight the welfare impact of the disorder on affected dogs.”

Prevalence of disorders recorded in Cavalier King Charles Spaniels attending primary-care veterinary practices in England. Jennifer F Summers, Dan G O’Neill, David B Church, Peter C Thomson, Paul D McGreevy, David C Brodbelt. Canine Genetics and Epidemiology. April 2015;2:4. Quote: "This study used large volumes of health data from UK primary-care practices participating in the VetCompass animal health surveillance project to evaluate in detail the disorders diagnosed in a random selection of over 50% of dogs recorded as Cavalier King Charles Spaniels (CKCSs). Confirmation of breed using available microchip and Kennel Club (KC) registration data was attempted. Results: In total, 3624 dogs were recorded as CKCSs within the VetCompass database of which 143 (3.9%) were confirmed as KC-registered via microchip identification linkage of VetCompass to the KC database. ... Microchip data were available in 1692 (46.7%) of the 3624 identified CKCSs. It was possible to crosslink microchip data with KC-registration details in 143 of these dogs; this represented 8.5% of all identified CKCSs with microchip data, and 3.9% of all identified CKCSs. The remaining 3481 dogs were classified as of unknown KC-registration status. The 52% randomly selected sample of all identified CKCSs totalled 1875 dogs: 1800 with unknown and 75 with confirmed KC-registration status. These 1875 dogs were seen at 109 individual clinics during the study period, including 90 (83%) Medivet and 19 (17%) Vets4Pets sites located from north-east to southern England. ...1875 dogs (75 KC registered and 1800 of unknown KC status, 52% of both groups) were randomly sampled for detailed clinical review. Clinical data associated with veterinary care were recorded in 1749 (93.3%) of these dogs. ... Median ages at first and last consultation were 4.0 and 5.25 years, respectively (ranges one month - 17.2 years for both age measures). The most frequent coat colours were Blenheim (44.3%) and tri-colour (30.8%) (Table 1). Of the 1521 dogs with more than one clinical data entry, median time contributed to the study was 1.3 years (range 1 day to 3.6 years). ... Magnetic Resonance Imaging (MRI) diagnoses of syringomyelia (SM), canine Chiari malformation (CM) and both concurrently were recorded in 19 (1.1%; 95% CI 0.7 -1.7%), 4 (0.2%; 95% CI 0.07 - 0.6%) and 10 (0.6%; 95% CI 0.3 - 1.1%) of study dogs, respectively. Thus, diagnosis of SM, CM or both was recorded in 33 (1.9%; 95% CI 1.3 – 2.7%) of study dogs overall. Syringomyelia ranked 28th among specific diagnoses most frequently recorded. Meaningful statistical comparison of diagnostic frequencies between KC-registration status groups was not possible due to the relatively low numbers of KC registered dogs identified. ... MRI-confirmed diagnoses of either syringomyelia, CM or both were recorded in approximately 2% of study dogs, with syringomyelia ranked 28th among the most frequently recorded specific diagnoses. Including only those diagnoses of either condition made with reference to MRI results (i.e. excluding those suggested by clinical signs alone) could have underestimated the true level in the population, as not all clinically suspicious cases underwent MRI scanning. The sometimes vague nature of clinical signs may result in failure to offer scanning in some cases, while reluctance (or financial limitations) of owners to pursue MRI diagnosis may be the limiting factor in others. Bias linked to comparative willingness to request high level diagnostic investigation may be of particular relevance in breeding animals, if breeders are more (or less) likely to volunteer breeding animals for MRI through screening programs. The link between signs of SM/CM visible on MRI and appearance of clinical signs can also be inconsistent, as not all dogs with a visible syrinx on MRI display clinical signs at the time of imaging. ... Further work This work highlights the value of veterinary practice based breed-specific epidemiological studies to provide targeted and evidence-based health policies. Further studies using electronic patient records in other breeds could highlight their potential disease predispositions."

Medullary Position at the Craniocervical Junction in Mature Cavalier King Charles Spaniels: Relationship with Neurologic Signs and Syringomyelia. S. Cerda-Gonzalez, N.J. Olby, E.H. Griffith. J.Vet.Int.Med. April 2015. Quote: "Background: Medullary elevation (ie, medullary kinking) at the craniocervical junction (CCJ) is reported in dogs with Chiari-like malformations (CM), but its diagnostic criteria and clinical relevance are unclear. Objective: To describe the position of the medulla at the CCJ in mature cavalier King Charles spaniels (CKCS), and evaluate its relationship with clinical status and the presence of syringomyelia. Animals: Thirty-six CKCS, 5–12 years of age [median age: 9 years], including 16 asymptomatic dogs. Methods: Dogs were assigned a neurologic grade; magnetic resonance imaging (MRI) of the CCJ then was performed. The presence of a CM and syringomyelia was recorded and syringomyelia severity was quantified. Medullary position was quantified using the medullary kinking index, the elevation angle and obex position relative to the foramen magnum. The relationship between medullary position measures and presence and severity of neurologic signs and syringomyelia was investigated. Results: Chiari-like malformation was found in 33 dogs; 26 of them had syringomyelia. Mean medullary kinking index was 46.4% (SD, 10.3), elevation angle was 132° (SD, 12) and obex position [caudodorsal-most border of the fourth ventricle] was 3.5 mm (SD, 0.8). A higher medullary kinking index was associated with the presence of neurologic signs (P = .0368). Obex position was associated with the presence (P = .0018) and severity of syringomyelia (P = .0164). ... In addition, an obex position measurement of ≤3.5 was sensitive (79%) and highly specific (90%) for the presence of syringomyelia. ... Conclusions and clinical importance: There is a significant association between medullary elevation and clinical signs, whereas more caudal brainstem positions appear related to the presence of syringomyelia."

Relationship between the clinical findings, MRI findings and the efficiency of the prescribed drugs in Cavalier King Charles Spaniels with Chiari-like malformation and syringomyelia (CM/SM). Schuil, D.A. Utrecht Univ. May 2015. Quote: "CM is a combination of malformation of the hindbrain and the surrounding caudal cranial fosssa and a consequential herniation of part of the cerebellum and brainstem into or through the foramen magnum reported in small breed dogs. SM is currently defined as a condition that results in the development of fluid-containing cavities within the parenchyma of the spinal cord as a consequence of abnormal cerebrospinal fluid movement. In this study the association between the findings on MRI and the reported clinical signs were investigated, this was done by using a hard copy survey about clincial signs observed by cavalier king charles spaniel (CKCS) owners that were scanned and MRI findings of those 848 CKCS [scanned in the Netherlands]. ... There are two aims in this study; the first is to investigate the association between the findings on magnetic resonance imaging (MRI) and the reported clinical signs observed by the individual owners, the second is to do a retrospective study to investigate the effect of prescribed drugs. ... One of the 844 dogs that were scanned did not have chiari malformation. 704 dogs were diagnosed with chiari malformation grade 2 (CM2) and 139 dogs were diagnosed with chiari malformation grade 3 (CM3). ... 555 of the 844 scanned dogs did not have syringomyelia. 9 dogs were diagnosed with syringomyelia grade 1 (SM1), 106 dogs were diagnosed with syringomyelia grade 2 (SM2), 10 dogs were diagnosed with syringomyelia grade 3 (SM3) and 164 dogs were diagnosed with syringomyelia grade 4 (SM4). ... 233 completed surveys were returned. According to the owners 45 dogs have complaints (19,3%) and 188 dogs do not have complaints (80,7%). ... It appeared that there were no significant relationships between the observed clincial signs and the grade of CM/SM found on the MRI scans. The owners were also asked about the efficiency of the prescribed drugs in their dogs, because of a lack of response, no conclusions could be drawn from this question. ... The aim of this study was to find a relationship between the clinical findings, MRI findings and the efficacy of the prescribed drugs in CKCS with CM/SM. Unfortunately only a few surveys were returned. A total of 45 surveys were completely filled in by owners from CKCS with complaints. Hence, the results are not sufficient enough to fully explore associations between clinical signs and the grade of SM (the MRI findings). Furthermore, as all dogs suffer from either CM 2 or 3, it is not possible to extrapolate for CM 0 to CM 3 and the clinical signs."

Comparison of the Relationship between Cerebral White Matter and Grey Matter in Normal Dogs and Dogs with Lateral Ventricular Enlargement. Martin J. Schmidt, Steffi Laubner, Malgorzata Kolecka, Klaus Failing, Andreas Moritz,  Martin Kramer, Nele Ondreka. PLoS ONE 10(5): e0124174. May 2015. Quote: "Large cerebral ventricles are a frequent finding in brains of dogs with brachycephalic skull conformation, in comparison with mesaticephalic dogs. It remains unclear whether oversized ventricles represent a normal variant or a pathological condition in brachycephalic dogs. There is a distinct relationship between white matter and grey matter in the cerebrum of all eutherian mammals. The aim of this study was to determine if this physiological proportion between white matter and grey matter of the forebrain still exists in brachycephalic dogs with oversized ventricles. The relative cerebral grey matter, white matter and cerebrospinal fluid volume in dogs were determined based on magnetic-resonance-imaging datasets using graphical software. In an analysis of covariance (ANCOVA) using body mass as the covariate, the adjusted means of the brain tissue volumes of two groups of dogs were compared. Group 1 included 37 mesaticephalic dogs of different sizes with no apparent changes in brain morphology, and subjectively normal ventricle size. Group 2 included 35 brachycephalic dogs [including 7 cavalier King Charles spaniels, 4 of which were diagnosed with syringomyelia] in which subjectively enlarged cerebral ventricles were noted as an incidental finding in their magnetic-resonance-imaging examination. Whereas no significant different adjusted means of the grey matter could be determined, the group of brachycephalic dogs had significantly larger adjusted means of lateral cerebral ventricles and significantly less adjusted means of relative white matter volume. This indicates that brachycephalic dogs with subjective ventriculomegaly have less white matter, as expected based on their body weight and cerebral volume. Our study suggests that ventriculomegaly in brachycephalic dogs is not a normal variant of ventricular volume. Based on the changes in the relative proportion of WM and CSF volume, and the unchanged GM proportions in dogs with ventriculomegaly, we rather suggest that distension of the lateral ventricles might be the underlying cause of pressure related periventricular loss of white matter tissue, as occurs in internal hydrocephalus. ... The influence of ventriculomegaly on brain function in dogs is unclear. Detailed behavioural studies of the impact of WM loss on the full functional integration of the nervous system are necessary to clarify whether ventriculomegaly might be an indication for CSF shunting procedures in dogs."

Dorsal Compressive Atlantoaxial Bands and the Craniocervical Junction Syndrome: Association with Clinical Signs and Syringomyelia in Mature Cavalier King Charles Spaniels. S. Cerda-Gonzalez, N. J. Olby, E. H. Griffith. J.Vet.Int.Med. May 2015;29(3):887-892. Quote: Background: Dorsal compressive lesions at the atlantoaxial junction (ie, AA bands) occur in dogs with Chiari-like malformations (CMs), but their clinical relevance is unclear. Objective: Investigate the influence of AA bands on clinical status and syringomyelia (SM) in mature cavalier King Charles spaniels (CKCS). Animals: Thirty-six CKCS, 5–12 years of age, including 20 dogs with neuropathic pain. Methods: Dogs were examined and assigned a neurologic grade. Magnetic resonance imaging (MRI) of the craniocervical junction was performed with the craniocervical junction extended and flexed (ie, normal standing position). Imaging studies were assessed for the presence of an AA band, CM, SM or some combination of these findings. Band and SM severity were quantified using an objective compression index and ordinal grading scale, respectively. Results: Of 36 CKCS imaged, 34 had CM. Atlantoaxial bands were present in 31 dogs and were more prominent in extended than flexed positions. Syringomyelia was found in 26 dogs, 23 of which also had AA bands. Bands were associated with both the presence (P = .0031) but not the severity (P = .008) of clinical signs whereas their presence was associated with both the presence and severity of SM (P = .0147, P = .0311, respectively). Higher compression indices were associated with more severe SM (P = .0137). Conclusions: Prevalence of AA bands in older CKCS is high. Positioning of dogs in extension during MRI enhances the sensitivity of the study for detecting this important abnormality. There were significant associations among AA bands, clinical signs, and SM in dogs with CM; additional work is needed to understand whether or not this relationship is causal. (See also, Erratum published March 2020 here.)

MRI characteristics of atlanto-axial subluxation in 42 dogs. Kathryn Bray, Simon R. Platt, Marc Kent, Allison Haley, Jill Narak, Amy W. Hodshon, Natasha J. Olby, Shannon P. Holmes. J.Vet.Int.Med. July 2015;29(4):1122–1256;N-19. Quote: "The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) characteristics of canine atlanto-axial (AA) subluxation and to identify associations with neurologic deficits. A multicenter review of the medical records and MR images of dogs with a diagnosis of AA subluxation was conducted. Signalment, neurologic grade, time to onset of signs, and MRI characteristics were recorded. The evaluated MRI characteristics included (1) spinal cord compression, (2) degree of joint subluxation, (3) integrity of odontoid ligamentous structures, (4) presence of a dens, (5) presence of cord signal intensity, and (6) presence of syringohydromyelia, hydrocephalus, and Chiari-like malformation. A control population of age and breed matched dogs with normal AA junctions were also evaluated. Reviewers were blinded to affected status. MR images of 42 dogs affected with AA subluxation were reviewed and compared to 26 control dogs. The majority of affected dogs were Yorkshire Terriers (47.5%). The median age was 27 months. The median weight was 2.7 kg. The control population had a median age of 96 months, and a median weight of 4.7 kg; the most common breeds were Maltese (18.5%) and Pomeranian (18.5%). 28% of dogs were affected less than 1 week, 30% were affected between one week and one month, and 42% were affected for greater than 1 month. Neurologic grade ranged from 1 (spinal pain only) to 5 (tetraplegic without nociception), but 50% of affected dogs were ambulatory tetraparetic (grade 2). Associations of MRI characteristics with affected status of dog (AA subluxation or control) and neurologic grade were assessed by logistic regression. Associations of MRI characteristics with each other was performed using Spearman and Pearson correlations, student t-tests, analysis of variance and Kruskal-Wallis tests as appropriate. No differences were noted between the affected and control dogs with respect to the presence of syringohydromyelia, hydrocephalus and Chiari-like malformation. Significant differences between control and affected dogs were noted with respect to presence of a dens, apical ligament, and transverse ligament. The presence of cord signal intensity was associated with affected status, as was increased AA joint cavity size and percentage crosssectional cord compression at the level of the dens and mid-body C2. No associations were found between cord compression, appearance of the dens or cord signal intensity and neurologic grade of affected dogs. There was an association between the presence of cord signal intensity and increased joint cavity size. There was no association between dens appearance and cord signal intensity. Dens abnormalities were associated with greater subluxation distance and odontoid ligament absence was associated with increased joint cavity size. Dogs affected by AA subluxation do not have a higher incidence of Chiari-like malformation, syringohydromyelia, or hydrocephalus than control dogs, and their neurologic grade is not associated with MRI findings. However, lack of a dens and/or odontoid ligaments are associated with larger subluxations."

Chiari-tyyppinen Epämuodostuma Ja Syringomyelia: Esiintyminen Muilla Roduilla Kuin Cavalier Kingcharlesinspanielilla [Chiari malformation and syringomyelia in breeds other than the Cavalier King Charles Spaniel]. Johanna Forsgård. Univ. of Helsinki thesis. June 2015. Quote: ""The aim of this study was to find out how much breeds other than the Cavalier King Charles Spaniel taken to the Helsinki University Teaching Hospital for head MRI scans showed Chiari-like malformation and Syringomyelia. Furthermore, the purpose was to gather current knowledge of the disease pathophysiology, symptoms, diagnosis, treatment, genetics and breeding. On the basis of my results, Chiari-like malformation seems to occur fairly commonly in other breeds, regardless of the size or shape of the skull. Syringomyelia, in turn, was seen much less. It would thus appear that syringomyelia is not always related to Chiari-like malformation, but perhaps there are other factors required. The results also question the studies with control groups have been used in France and labradors, because even these breeds were found to have Chiari-like malformation."

Attempts to breed out chiari-like malformation: is a cross the answer? Susan Knowler, Henny van den Berg, Eric Noorman, Roberto La Ragione, Clare Rusbridge. J.Vet.Int.Med. July 2015;29(4):1257–1283. Quote: "Chiari-like malformation (CM) and syringomyelia (SM) are complex inherited disorders observed most commonly in toy breed dogs and can cause a significant loss in quality of life though pain and disability. Brachycephalicism is a risk factor and it has been suggested that crossbreeding with a different breed/s then backcrossing may produce individuals free of disease. This two and a half year project took advantage of a cross between a mesaticephalic normal Australian terrier and CM affected Griffon Bruxellois (GB) with subsequent backcrossing to a GB to investigate the inheritance and phenotype of these conditions and a means of reducing the incidence of CM and risk of SM. The study cohort comprised 2 control dogs (CM affected Australian terrier and unrelated GB without CM) and a single of family of 29 dogs, 12 of which were used in 8 different mating combinations resulting in 19 progeny. T1-weighted sagittal DICOM images were analyzed for traits (2 angles, 2 lines and a “best fit” circle diameter) shown previously to have the greatest significance for CM in the GB. The quantitative findings in this study revealed these traits to be significant for CM-affectedness. Furthermore the external phenotypes showed that by outcrossing breed types and selecting appropriate conformation characteristics in the F1 generation, it is possible to regain the GB breed standard in the F2 generation and reduce the degree of CM. However this is dependent on careful selection of conformation and screening for CM and SM at 1 year of age. The 4 dogs affected with SM in the study all exhibited reduced caudal skull development compared to their relatives. We showed that traits on MR images were useful to distinguish the phenotype and these exhibited segregation and may be additive towards the severity of CM. It suggests such traits might be useful to quantify the condition and the risk to SM. We propose that grading of CM takes account of quantitative traits that can be used in Estimated Breeding Values (EBV) to assist breeders with their mate selections. Such a system will have to be verified to ensure appropriateness for all breeds at risk."

Low-Field Magnetic Resonance Imaging and Multislice Computed Tomography for the Detection of Cervical Syringomyelia in Dogs. K. Kromhout, H. van Bree, B.J.G. Broeckx, S. Bhatti, S. De Decker, I. Polis, I. Gielen.J. Vet. Int. Med. September 2015;29(5):1354-1359. Quote: "Background: Syringomyelia (SM) is defined as the presence of fluid-containing cavities within the parenchyma of the spinal cord. Sagittal magnetic resonance (MR) images have been described as the preferred technique for visualizing SM in dogs and humans. Objective: To investigate whether computed tomography (CT) can be used to diagnose SM. Animals: Thirty-two client-owned dogs referred for investigation of the cervical spine on magnetic resonance imaging (MRI) and CT [including 12 cavalier King Charles spaniels - CKCSs]. Methods: Two reviewers retrospectively analyzed sagittal and transverse T1-weighted spin echo (T1WSE) MR images and CT images from each dog for the presence of SM and, if SM was present, the width (mm, syrinx width [SW]) was measured. The results were analyzed statistically. Results: ... Results of this study demonstrate that low-field MR and multislice CT imaging provide comparable information regarding the presence of SM. ... For the presence of SM there was a moderate interobserver agreement for MR (81%, κ = 0.54) and almost perfect agreement for CT (94%, κ = 0.87). There was a moderate intramodality agreement for both observers (observer 1 81%, κ = 0.59; observer 2 81%, κ = 0.57). For measurement of SW the repeatability was the best on the midsagittal T1WSE images (95% repeatability coefficient <0.52 mm) and the reproducibility was the best on midsagittal images in both modalities (95% limits of agreement −0.55–0.45; P = 0.002). Conclusion and Clinical Importance: Both techniques can be used to detect SM. Midsagittal MR and CT images are best used for measuring SW. ... The central canal is normally just appreciable on MR images and not visible in normal circumstances on CT images. However, any dilatation of the central canal should be considered abnormal. Hence, the detection of smaller dilatations on both MR and CT is important as progressive central canal dilatation is a precursor of syrinx formation. Furthermore, results of a previous study suggest that SW progresses with time in CKCS. ... Krommhout 2015 Study - Figure 3This study did not find an association between the detection of a small dilatation and use of technique. [Figure 3.] The difference in detection and measurement can be attributed to the experience of the observer and the presence of several of the artifacts mentioned earlier. Overall, we conclude that SM is consistently identified by different observers on CT and on MRI. In addition, the results of this study suggest that when a syrinx is detected the highest agreement is present for measuring SW on both the midsagittal MR and CT images. Syringomyelia and SW have been shown to explain at least some of the clinical signs in dogs. As CT scanners are more readily available in veterinary practices compared with MRI equipment, CT can be used as a diagnostic tool for SM when MRI is not available. Cerebellar herniation is consistently identified by different observers on CT and on MR images of CKCS. Bearing this in mind, we can conclude, that CT can be used as an alternative imaging technique for Chiari-like malformation/SM in CKCS when MRI is not available. We emphasize that, at the current time, CT cannot replace MRI as the standard screening technique for the detection of SM in CKCS for breeding purposes, more specific for the detection of the presyrinx state." See also, "Low-Field MRI and Multislice CT for the Detection of Cerebellar (Foramen Magnum) Herniation in Cavalier King Charles Spaniels", by the same team of researchers.

Comparison of gabapentin versus topiramate on clinically affected dogs with Chiari-like malformation and syringomyelia. I. N. Plessas, H. A. Volk, C. Rusbridge, A. E. Vanhaesebrouck, N. D. Jeffery. Vet. Rec. September 2015;177:288. Quote: "To date there is no evidence-based data for efficacious treatment of neuropathic pain in dogs with Chiari-like malformation (CM) and syringomyelia (SM). ... The aim of this study was to compare prospectively, in a cross-over trial, the effect of gabapentin versus topiramate, as an adjunctive treatment to carprofen, on QoL of clinically affected CKCS with CM/SM, as assessed by the owners using a visual analogue scale (VAS), and record any adverse effects. Forty Cavalier King Charles spaniel dogs were included in the trial from three different referral hospitals in the UK. ... A visual analogue scale (VAS) was used to assess the QoL: (1) on day 0; (2) after 1 week of carprofen only; (3) after 2 weeks on carprofen and gabapentin; and (4) after 2 weeks on carprofen and topiramate. No significant difference was observed between VAS after gabapentin or topiramate (P=0.91). However, an improvement in QoL was observed when gabapentin was compared with baseline (P=0.009), but not for topiramate. ... In this prospective, randomised, cross-over study in clinically affected CKCS with CM/SM no significant difference was observed on their QoL when gabapentin was compared with topiramate. Data also suggests that the addition of either of these two drugs may be more effective than carprofen alone. Sedation was the most common adverse effect of both drugs with the addition of inappetence for topiramate; however the adverse effects associated with the latter drug were more severe. In conclusion, gabapentin’s more favourable adverse effect profile may be more suitable than topiramate in dogs experiencing NeP, but further placebo-controlled prospective studies will be needed to better establish the comparative effect of these drugs. ... Perhaps the more favourable side effect profile of the former makes it more suitable for the treatment of neuropathic pain associated with CM/SM but further placebo-controlled trials are required to assess the efficacy of these drugs."

Association between the identification of a syrinx in asymptomatic cavalier King Charles spaniels and the subsequent development of clinical syringomyelia. A. Vanhaesebrouck, L. Doyle, M. Holmes, T. Williams, E. Ives. 27th ESVN-ECVN Symposium. J.Vet.Int.Med. August 2015; ESVN-ECVN Abstracts p.12. Quote: "The aim of this study was to determine whether the presence of a syrinx on pre-breeding MRI screening in an asymptomatic Cavalier King Charles Spaniel (CKCS) could predict the likelihood of a dog developing clinical signs consistent with syringomyelia in later life. Owners of CKCS that were screened for the presence of a syrinx on MRI between 2006 and 2009 were asked to complete a questionnaire regarding signalement, general health and common syringomyelia symptoms in 2013. Only dogs that were reported to be asymptomatic at the time of MRI were included, and dogs with concurrent diseases were excluded from the study. MRI scans of the craniocervical region were reviewed in random, blinded fashion. The data were analyzed by binary logistic regression. Seventy-nine questionnaires fulfilled the inclusion criteria. Dogs were scanned at a median age of 2.6 years [IQR 2.2–3.5 years], with a syrinx identified on MRI in 32% of dogs. Sixteen percent of dogs developed clinical signs compatible with syringomyelia, with a median age at onset of 5 years [IQR 4–7 years]. A higher proportion of dogs with a syrinx visible on MRI screening developed clinical signs consistent with syringomyelia in later life (36%), when compared to dogs without a visible syrinx (7%) (Hazard ratio, 6.1; p = 0.003). None of the other variables entered in the logistic regression analysis reached statistical significance. The presence of a syrinx on MRI screening appears to represent a risk factor for the subsequent development of clinical signs consistent with syringomyelia in CKCS."

Pulse wave myelopathy: An update of an hypothesis highlighting the similarities between syringomyelia and normal pressure hydrocephalus. Grant A. Bateman. Med. Hypotheses. September 2015. Quote: "Most hypotheses trying to explain the pathophysiology of idiopathic syringomyelia involve mechanisms whereby CSF is pumped against a pressure gradient, from the subarachnoid space into the cord parenchyma. On review, these theories have universally failed to explain the disease process. A few papers have suggested that the syrinx fluid may originate from the cord capillary bed itself. However, in these papers, the fluid is said to accumulate due to impaired fluid drainage out of the cord. Again, there is little evidence to substantiate this. This proffered hypothesis looks at the problem from the perspective that syringo-myelia and normal pressure hydrocephalus are almost identical in their manifestations but only differ in their site of effect within the neuraxis. It is suggested that the primary trigger for syringomyelia is a reduction in the compliance of the veins draining the spinal cord. This reduces the efficiency of the pulse wave dampening, occurring within the cord parenchyma, increasing arteriolar and capillary pulse pressure. The increased capillary pulse pressure opens the blood-spinal cord barrier due to a direct effect upon the wall integrity and interstitial fluid accumulates due to an increased secretion rate. An increase in arteriolar pulse pressure increases the kinetic energy within the cord parenchyma and this disrupts the cytoarchitecture allowing the fluid to accumulate into small cystic regions in the cord. With time the cystic regions coalesce to form one large cavity which continues to increase in size due to the ongoing interstitial fluid secretion and the hyperdynamic cord vasculature."

Treating Chiari-like malformation and syringomyelia in dogs. C. Stalin. Vet. Rec. September 2015;177:286-287. Quote: "Chiari-like malformation and syringomyelia is well recognised in Cavalier King Charles spaniels. Syringomyelia is characterised by cavitation of the spinal cord leading to disruption of the decussating spinothalamic fibres. In people with syringomyelia, pain is a prominent feature in 50 to 90 per cent. Patients typically present with complaints of radicular pain, interscapular pain, and/or central cord pain. In addition to the more common clinical pain syndromes, approximately 40 per cent of patients with syringomyelia experience significant dysaesthetic pain, which is variously described as a burning sensation, pins and needles, or stretching of the skin (Todor and others 2000). Chronic pain resulting from injury to either the peripheral or central nervous system is referred to as neuropathic pain. Neuropathic pain in animals is difficult to recognise as, unlike people, they are not able to voice the discomfort and abnormal sensations. However, owners of Cavalier King Charles spaniels with syringomyelia will report a typical history of yelping, scratching behaviour, apparent discomfort or avoidance of being touched over the ear, neck, shoulder or sternum or abnormal head posture (Rusbridge and others 2007). It is therefore assumed that these dogs are suffering from neuropathic pain similar to that described by their human counterparts. In order to establish appropriate medical therapy in dogs with syringomyelia, our justification needs to be based on more than anecdotal evidence in individual dogs. On this basis, Rusbridge and Jeffery (2008) suggested the need for a mutilcentre approach to rationalise medical management of syringomyelia. Therefore, seven years later, Plessas and others (2015), in a paper summarising the results of a prospective, randomized cross-over trial to assess the efficacy of gabapentin versus topiramate as an adjunctive treatment to carprofen in clinically affected dogs wth syringomyelia. Gabapentin and topiramate are both anticonvulsant medications that have been used to treat neuropathic pain in people, with gabapenin problably being the more effective of the two (Finnerup and others 2005, Khoromi and others 2005). Despite the lack of evidence-based data, gabapentin is widely used in veterinary medicine to treat suspected neuropathic pain."

Atlantooccipital Overlap and Other Craniocervical Junction Abnormalities in Dogs. Catherine A. Loughin, Dominic J. Marino. Vet. Clin. Small Animal. November 2015. Quote: "Craniocervical junction abnormalities (CJA) are being recognized more frequently in veterinary patients. The term CJA is an umbrella term for a variety of malformations that occur in the craniocervical region. Chiari-like malformation (CLM) is commonly diagnosed in small-breed dogs, and is defined as an abnormal-shaped supraoccipital bone resulting in rostral compression of the caudal aspect of the cerebellum. This is the most commonly diagnosed CJA, but other malformations include atlantooccipital overlapping (AOO), atlantoaxial instability, occipitoatlantoaxial malformation (OAAM), atlantoaxial dural bands, and dens abnormality. Determining the structural cause of cerebellar compression is difficult on MRI because of poor bone visualization, but with the addition of computed tomography (CT) and three-dimensional reconstruction these structural abnormalities become easier to recognize. The term craniocervical junction abnormality (CJA), as used in human medicine, serves as an umbrella term for a variety of malformations that occur in the craniocervical region. MRI of craniocervical junction abnormalities with CT imaging are necessary to fully evaluate CJAs. Most dogs with atlantooccipital overlapping (AOO) respond temporarily to medical management. Like CLM/SM, we often consider AOO to be a surgical disorder.

What is Chiari Malformation (COMS)? Jason King. Live Oak Vet. Neuro. December 2015. Quote: "Chiari malformation is the term used in human medicine that equates in veterinary medicine to Caudal Occipital Malformation Syndrome, COMS. The most commonly affected breed with COMS is the Cavalier King Charles Spaniel. ... COMS is a condition where the base of the skull in the dog is abnormally shaped. This leads to a more 'rounded skull' and, in turn, causes the part of the brain at the base of the skull (the cerebellum) to be 'crowded'. Because this skull defect is present at birth and through the growth phase of the puppy, once the dog reaches adulthood, the skull changes are static and don't change. But the after-effects are progressive. You see, COMS is associated with another condition that takes place in the spinal cord 'downstream' from the skull in the dog's neck. This condition is called syringohydromyelia or SM. SM is a progressive degenerative condition in the spinal cord that can happen anytime the flow of spinal fluid is disrupted. The part of the spinal cord that is towards the chest of a person or animal carries information from the brain to the body, instructions on how to move. The part of the spinal cord towards the back of the person or animal carries information from the body to the brain, sensory information if you will. Interestingly enough, SM almost always forms in the sensory part of the spinal cord. So it leads to abnormal sensations rather than weakness or abnormal movments. That means that dogs with SM manifest some very odd and quite varied behaviors secondary to the abnormal sensations that their spinal cord is causing them to feel. Imagine, that every time you got excited your toes began to itch and burn, your ear began to feel hot, or your arm became numb and tingly... The most striking manifestation of this abnormal sensation is called 'phantom scratching'. In this situation, dogs will begin to scratch 'at' their ear, but just a little bit off to the side. Almost as if they were scratching the air! Diagnosis of COMS and SM requires an MRI. No other tests are able to definitively diagnose this condition. There are other tests that have been used to support the diagnosis though, including BAER hearing tests, CT scans, ultrasound, and even infrared imaging. Treatment for COMS is sometimes medical, and sometimes surgical. There are several drugs that can be used to help control the condition, and surgery can be very successful (depending on how one defines 'success')."

Computer simulation of the canine spine: the effects of increased spinal cord motion on the developemnt of Syringomyelia. R. Lloyd, S. Cirovic, J. Jovanovik, H. Volk, C. Rusbridge. ESVN Abstract J. Vet. Int. Med. December 2015. Quote: Syringomyelia is a disorder characterized with the presence of fluid-filled cavities in the spinal cord. The condition occurs in both humans and animals. The mechanism(s) of cavity formation are not clear, leading to limited treatment. Current theories are based on the assumption that abnormities in the circulation of the cerebrospinal fluid (CSF) generates pressures that drive the fluid into the cord. A finite element model was constructed using geometry extracted from MRI scans of a Cavalier King Charles spaniel with syringomyelia, to explore possible mechanisms of syrinx formation. The model included the spinal cord, subarachnoid space (SAS), dura mater, and the epidural space. It has been shown in patients with restricted CSF flow, that there is exaggerated movement of the spinal cord during the cardiac cycle. This motion was applied to the cranial end of the spinal cord of the model. The peak longitudinal and radial pressure differences in the SAS oscillated between −22.3 to +90.0 Pa, and −100 to +100 Pa, respectively. Low-amplitude cyclic shear stresses were present in the cervical spinal cord (C2 – C6), where the cavities typically originate. In conclusion it was proposed that the CSF pressure gradients are unlikely to cause fluid movement into the cord, sufficient to generate syrinxes. On the other hand, although the shear stress in the cord is low, its location and cyclic nature indicates the possibility that this may be the factor that generates the initial tissue damage, which eventually leads to the formation of syrinxes. (See also this March 2018 article by the same research team.)

Chiari-Like Malformation with Syringomyelia in the Small Breed Dogs: Prognosis Evaluation after Surgical Management (Case Report). Sung-Su Park, Hyun-Ju Kim, Jung Min Ryu, Ho Jae Han. Global Veterinaria. 2015;15(1):129-132. Quote: Small breed dogs were visited for the evaluation of neurologic deficits. On neurologic examination, all dogs were showed hyperesthesia, pain, neck stiffness or ataxia. After diagnosis by magnetic resonance imaging (MRI) dogs had cranial cervical decompression with durotomy. These dogs had the durotomy patched with autologous subcutaneous fat. The clinical signs of all dogs improved postoperatively. This case report demonstrates to evaluate success of cranial cervical decompression for management of canine chiari-like malformation with syringomyelia (CM/SM). ... In this report, cranial cervical decompression surgery for CM/SM has low mortality and morbidity and in dogs with pain the procedure can improve quality of life; however, syrinx collapse seemingly does not occur and resolution may be related to other factors involved in the development and/or persistence of syringomyelia. Surgical management may be regarded as not resolve the syringomyelia, but prevent the deterioration of syringomyelia. Therefore, the timing of surgical management is very important for the good prognosis. Further, based on these dogs, it is suggested that to properly evaluate the success of any surgical technique for CM/SM that postoperative MRI scans be performed because clinical improvement does not necessarily imply radiographic improvement.

Figure 2 - Before and After

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2016

Cranial suture closure in domestic dog breeds and relations to skull morphology. Madeleine Geiger, Sinah Haussman. Anatomical Record. January 2016. Quote: "Bulldog-type brachycephalic domestic dog breeds are characterised by a relatively short and broad skull with a dorsally rotated rostrum (airorhynchy). Only few is known about the association between a bulldog-type skull conformation and peculiar patterns of suture and synchondrosis closure in domestic dogs. In this study, we aim to explore breed-specific patterns of cranial suture and synchondrosis closure in relation to the prebasial angle (proxy for airorhynchy and thus bulldog-type skull conformation) in domestic dogs. For this purpose, we coded closure of 18 sutures and synchondroses in 26 wolves – the wild ancestor of all domestic dogs – and 134 domestic dogs comprising 11 breeds. Comparisons of the relative amount of closing and closed sutures and synchondroses (closure scores) in adult individuals showed that bulldog-type breeds have significantly higher closure scores than non-bulldog-type breeds and that domestic dogs have significantly higher closure scores than the wolf. We further found that the prebasial angle is significantly positively correlated with the amount of closure of the basispheno-presphenoid synchondrosis and sutures of the nose (premaxillo-nasal and maxillo-nasal) and the palate (premaxillo-maxillary and interpalatine). Our results show that there is a correlation between patterns of suture and synchondrosis closure and skull shape in domestic dogs, although the causal relationships remain elusive."

Magnetic resonance imaging-based measures of atlas position: Relationship to canine atlantooccipital overlapping, syringomyelia and clinical signs. S. Cerda-Gonzalez, K.F. Bibi, A.T. Gifford, E.L. Mudrak, P.V. Scrivani. Vet. J. March 2016;209:133-138. Quote: "Canine atlantooccipital overlapping (AOO) is characterized by a decreased distance between the dorsal arch of the atlas and the supraoccipital bone. Current diagnostic criteria for this condition are subjective and clinician-dependent; objective criteria are needed to allow a reliable and reproducible diagnosis in clinical and research settings and assess clinical significance. We propose four standardized MRI-based measurements to objectively assess the proximity of the atlas to the foramen magnum. Inclusion criteria for dogs in this study were bodyweight <15 kg, age >5 months, and availability of a complete MRI study performed with the craniocervical junction in extension. Exclusion criteria were space-occupying lesions and poor image quality (i.e. unclear bony margins). Measurements also included blinded determinations of skull type, presence of craniocervical junction anomalies and presence and severity of syringomyelia. Clinical status at the time of imaging was noted. Measurements were obtained in 271 dogs; these were reproducible and reliable. Findings varied by skull type: dolichocephalic dogs had smaller foramen magnum, whereas brachycephalic dogs had more cranially and dorsally positioned atlas bodies in comparison to the other skull types. Measurements also increased with increases in bodyweight. This study demonstrated a close association between AOO, syringomyelia and clinical signs. Toy and small breed dogs (including Cavalier King Charles spaniels) showed higher than previously reported prevalence of AOO; its occurrence was also associated with lower bodyweights within the study population of <15 kg toy/small breed dogs. ... CKCS were more likely (86%) than non-CKCS (44%) to have AOO."

Evaluation of the effect of oral omeprazole on canine cerebrospinal fluid production: A pilot study. M. Girod, F. Allerton, K. Gommeren, A.C. Tutunaru, J. de Marchin, I. Van Soens, E. Ramery, D. Peeters. Vet. J. March 2016;209:119–124. Quote: "Administration of omeprazole by ventriculo-cisternal perfusion and/or intravenously has been shown to decrease cerebrospinal fluid (CSF) production in dogs and rabbits. Oral omeprazole has consequently been recommended to reduce CSF production in dogs with conditions in which clinical signs may be attributable to an accumulation of CSF in the central nervous system (e.g. hydrocephalus, syringomyelia). The albumin quotient (QAlb), the ratio between CSF and serum albumin concentration, has been proposed as a reliable means to evaluate CSF production; decreasing CSF production should cause an increase in QAlb. The aims of this study were to assess the effect of oral administration of omeprazole on QAlb in dogs and to compare two methods to assess CSF albumin concentration. Fifteen healthy Beagle dogs received omeprazole (1.2 mg/kg/day) orally for 14 days; CSF and blood were obtained before and after treatment. CSF albumin concentrations were evaluated by nephelometry and high-resolution protein electrophoresis. Regardless of the method used for measuring albumin, QAlb did not change significantly following oral omeprazole administration, suggesting that CSF production in healthy dogs may not be affected by chronic oral therapy with omeprazole."

Chiari-Like Malformation and Syringomyelia. Ates Barut. Balkanvets.com January 2016. Quote: "Chiari-like malformation is a hereditary condition and first described in king charles cavalier spaniels and altough several other small breeds can become effected king charles cavaliers are the most common breed effected by the disease. The other reported breeds are; Griffon, Miniature poodle, Yorkshire terrier, Maltese, Chihuahua, Bichon frise, Staffordshire terrier, Pug, Shih Tzu, Dachsund, Pincher, French bulldog, Jack Russel Terrier, Pekingese and Boston terriers. Affected patients has a kind of cerebellar compression and narrowing around foramen magnum and cervicomeduller junction. ... As a result chiari-like malformation and syringomyelia is one of the most important breed predispositions of veterinary medicine and although the disease is reported in several other breeds it creates a very important clinical problem among king charles cavalier population. Most of the patients with syringomyelia can live whole their lives with very mild symptoms within a normal life expectancies but some patients will have cervical myelopathy, cerebellovestibüler dysfunction and multifocal central nervous system dysfunction. Pain and life quality is the main concern and criteria for treatment. Patients with obvious neurological signs and pain and non-responsive to pain managment therapies are candidates for surgery. Foramen magnum decompression and syringo-subarachnoid shunt application are the two surgical procedures described to reorganize normal cerebrospinal fluid flow and drain syrinx from its cavity."
Barut, Chiari-like malformation drawingBarut, Normal

 Chiari-like Malformation. Catherine A. Loughin. Vet. Clin. Small Animal. March 2016;46(2):231-242. Quote: "Chiari-like malformation (CLM) is a condition of the craniocervical junction in which there is a mismatch of the structures of the caudal cranial fossa (CCF), often causing the cerebellum to herniate into the foramen magnum. Affected dogs have a smaller CCF with relatively more brain parenchyma within the fossa compared to unaffected dogs. This smaller CCF leads to cerebellar compression and herniation through the foramen magnum, kinking of the medulla, and disruption of cerebrospinal fluid (CSF) at this junction. This malformation is found most commonly in the Cavalier King Charles spaniel (CKCS), is inherited, and is thought to affect as much as 95% of the population. However, CLM has also been diagnosed in the Griffon Bruxellois and many other small breed dogs and is also analogous to Chiari type 1 malformation in humans. Chiari-like malformation is a condition in which there is a relatively small caudal cranial fossa volume with associated crowding of the brain parenchyma. Chiari-like malformation is diagnosed on MRI by identifying cerebellar herniation, cerebellar compression, and attenuation of cerebrospinal fluid, but kinking of the medulla, ventriculomegaly/hydrocephalus, and syringomyelia are also noted in many dogs. Some patients respond favorably to medical management; foramen magnum decompression with a durotomy is the surgical treatment of choice in improving or resolving clinical signs in dogs with Chiari-like malformation."

Managing Neuropathic Pain in Dogs. Sarah A. Moore. Frontiers in Vet. Sci. February 2016. Quote: "Disorders of the somatosensory system such as neuropathic pain are common in people with chronic neurologic and musculoskeletal diseases, yet these conditions remain an underappreciated morbidity in veterinary patients. This is likely because assessment of neuropathic pain in people relies heavily on self-reporting, something our veterinary patients are not able to do. The development of neuropathic pain is a complex phenomenon, and concepts related to it are frequently not addressed in the standard veterinary medical curriculum such that veterinarians may not recognize this as a potential problem in patients. The goals of this review are to discuss basic concepts in the pathophysiology of neuropathic pain, provide definitions for common clinical terms used in association with the condition, and discuss pharmacological treatment options for dogs with neuropathic pain. The development of neuropathic pain involves key mechanisms such as ectopic afferent nerve activity, peripheral sensitization, central sensitization, impaired inhibitory modulation, and pathologic activation of microglia. Treatments aimed at reducing neuropathic pain are targeted at one or more of these mechanisms. Several drugs are commonly used in the veterinary clinical setting to treat neuropathic pain. These include gabapentin, pregabalin, amantadine, and amitriptyline. Proposed mechanisms of action for each drug, and known pharmacokinetic profiles in dogs are discussed. Strong evidence exists in the human literature for the utility of most of these treatments, but clinical veterinary-specific literature is currently limited. Future studies should focus on objective methods to document neuropathic pain and monitor response to therapy in veterinary patients."

Cranial Suture Closure in Domestic Dog Breeds and Its Relationships to Skull Morphology. Madeleine Geiger, Sinah Haussman. Anatomical Rec. April 2016;299(4):412-420. Quote: "Bulldog-type brachycephalic domestic dog breeds are characterized by a relatively short and broad skull with a dorsally rotated rostrum (airorhynchy). Not much is known about the association between a bulldog-type skull conformation and peculiar patterns of suture and synchondrosis closure in domestic dogs. In this study, we aim to explore breed-specific patterns of cranial suture and synchondrosis closure in relation to the prebasial angle (proxy for airorhynchy and thus bulldog-type skull conformation) in domestic dogs. For this purpose, we coded closure of 18 sutures and synchondroses in 26 wolves, that is, the wild ancestor of all domestic dogs, and 134 domestic dogs comprising 11 breeds. Comparisons of the relative amount of closing and closed sutures and synchondroses (closure scores) in adult individuals showed that bulldog-type breeds have significantly higher closure scores than non-bulldog-type breeds and that domestic dogs have significantly higher closure scores than the wolf. We further found that the prebasial angle is significantly positively correlated with the amount of closure of the basispheno-presphenoid synchondrosis and sutures of the nose (premaxillo-nasal and maxillo-nasal) and the palate (premaxillo-maxillary and interpalatine). Our results show that there is a correlation between patterns of suture and synchondrosis closure and skull shape in domestic dogs, although the causal relationships remain elusive."

Inheritance of Chiari-Like Malformation: Can a Mixed Breeding Reduce the Risk of Syringomyelia. Susan P. Knowler, Henny van den Berg, Angus McFadyen, Roberto M. La Ragione, Clare Rusbridge. PLOSone. March 2016. Quote: "Canine Chiari-like malformation (CM) is a complex abnormality of the skull and craniocervical junction associated with miniaturization and brachycephaly which can result in the spinal cord disease syringomyelia (SM). ... The heritability of SM has been estimated in the Cavalier King Charles Spaniel (CKCS) as moderately high (h2 = 0.37 ± 0.15 standard error)  and prevalence increases with age. CM is ubiquitous in the CKCS and has an estimated prevalence of 65% in Griffon Bruxellois (GB). One study investigating the breeding programme of CKCS (n = 550) and GB (n = 93) found 70% and 73% respectively of offspring were free of SM if their parents were SM clear over 5 years of age but when both parents were SM affected the risk of SM was 92% in CKCS and 100% GB. ... This study investigated the inheritance of CM in a Griffon Bruxellois (GB) family and feasibility of crossbreeding a brachycephalic CM affected GB with a mesaticephalic normal Australian terrier and then backcrossing to produce individuals free of the malformation and regain GB breed characteristics. The study family cohort (n = 27) included five founder dogs from a previous baseline study of 155 GB which defined CM as a global malformation of the cranium and craniocervical junction with a shortened skull base and increased proximity of the cervical vertebrae to the skull. T1-weighted sagittal DICOM images of the brain and craniocervical junction were analysed for five significant traits (two angles, three lines) identified from the previous study and subsequent Qualitative Trait Loci analysis. Mean measurements for mixed breed, pure-breed and baseline study groups were compared. Results indicated that mixed breed traits posed less risk for CM and SM and were useful to distinguish the phenotype. Moreover on the MR images, the filial relationships displayed by the traits exhibited segregation and those presenting the greatest risk for CM appeared additive towards the severity of the condition. The external phenotypes revealed that by outcrossing breed types and with careful selection of appropriate conformation characteristics in the first generation, it is possible to regain the GB breed standard and reduce the degree of CM. The four GB affected with SM in the study all exhibited reduced caudal skull development compared to their relatives. The craniocervical traits may be useful for quantifying CM and assessing the possibility of SM thus assisting breeders with mate selection. However, such a system requires validation to ensure appropriateness for all breeds at risk."

Surgical stabilization of the atlanto-occipital overlap with atlanto-axial instability in a dog. Atsushi Fujita, Ryohei Nishimura. Japanese J. Vet. Research. May 2016;64(2):141-145. Quote: The atlanto-occipital (AO) overlap in combination with atlanto-axial (AA) instability was found in a dog [Chihuahua]. We hypothesized that ventral fixation of the AA junction can stabilize the atlas and prevent AO overlap by reviewing our past cases with AA instability. A standard ventral fixation of the AA junction using stainless k-wires and polymethyl methacrylate (PMMA) was performed. The dog fully recovered, and no complication was noted. The results of the postoperative CT imaging supported our hypothesis. The ventral fixation of the AA junction is a feasible treatment option for similar cases, although craniocervical junction abnormalities (CJA) including AA instability are varied, and careful consideration is required for each case.

Does medical therapy influence the size of the syrinx in dogs with Chiari-like malformation/syringohydromyelia complex? L. Motta. j. Small Anim. Pract. May 2016;57(5):278. Quote: "I wish to report on the effect of medical management on progression of syringohydromyelia (SHM) in cavalier King Charles spaniels with Chiari-like malformation (CM). Seven cavalier King Charles spaniels (age: 1 to 5 years; mean, 2·3 years) with history, clinical signs and MRI findings suggestive of Chiari malformation/syringohydromyelia received long-term (0·5 to 4·5 years; mean, 2·8 years) furosemide therapy (dose: 0·8 to 2 mg/kg twice daily; mean, 1·1 mg/kg twice daily) and had repeat MRI scans between 0·5 and 4·5 years (mean, 2·8 years) after diagnosis. Additional oral medications (gabapentin, corticosteroids and omeprazole) were prescribed when furosemide failed to control the clinical signs associated with CM/SHM complex. In all seven dogs, syrinx width and length increased at the follow-up MRI and in four cases a new syrinx had developed (Table 1). Furosemide did not prevent further syrinx expansion nor reduce the size of the syrinx but it remains unknown whether the medical treatment may have delayed the inevitable expansion of the syrinx. Studies of a larger population and prospective, randomised, blinded comparisons between different treatments (medical, surgical, medical vs surgical) are needed to ascertain which will produce the best clinical results."

Contents under pressure: vascular fibrous proliferation and gliosis within the brain of Cavalier King Charles spaniels affected with syringomyelia. Clare Rusbridge, Silvia Guilluna, Daniela Menezes, Duncan Grainger, Anna Tauro, Nicholas Jeffery, Fernando Constantinocasa, Penny Watson, Francisco Salguero. J. Small Anim. Pract. May 2016;57(Suppl. 1):38. Quote: Chiari-like malformation (CM) is characterised by shortening of the basicranium, reduced supraoccipital bone convexity, invagination of the cerebellum under the occipital lobes and into the foramen magnum and increased proximity of the atlas to the occiput. The neural tissue overcrowding within the craniocervical junction results in obstruction of cerebrospinal fluid pathways and failure to accommodate the arterial pulse wave leading to variable ventriculomegaly and syringomyelia (SM). The mechanism of SM is debated. The most accepted hypothesis is that there is a mismatch in timing between arterial and CSF pulse peak pressure resulting in fluid flowing into the perivascular space. However this theory is not well supported by histopathological studies of the spinal cord in the cavalier King Charles spaniel (CKCS). In this breed with a high prevalence of CM and SM, the dominant feature is angiogenesis and fibrous tissue proliferation in blood vessels adjacent to syrinx cavities suggesting a response to elevated intra-cord pressure. An alternative hypothesis of SM is that there is reduction in venous compliance resulting in increased pulse pressure, disruption of the blood brain barrier, increased interstitial fluid (pre-syrinx) and ultimately SM. In this retrospective cohort study we investigate the vascular changes related to CM and SM in the cerebral cortex. The formalin fixed brains from 26 CKCSs (18 affected by CM and SM with ventriculomegaly and 8 without SM) were processed for histopathological analyses. The pathological material had been obtained from dogs humanely destroyed and donated by their owners. Tissue sections were stained with haematoxilin and eosin, trichromic martius scarlet blue and immunohistochemistry for glial fibrillary acidic protein. Morphometric and digital image analyses were used to quantify the number of vessels, width of the arteriolar wall and number of astrocytes in the cerebrum adjacent to the lateral ventricles. SM affected animals showed a significant increase in the number of blood vessels, associated with an increase in the width of the arteriolar walls due to a proliferative fibrous response. Moreover, there was a significant astrogliosis and astrocytosis in the areas adjacent to the ependymum. The logical explanation of this histomorphological change is a mechanical response to elevated arterial pressure. This arterial stiffening may further affect the ability to reduce the arterial pulse wave and decrease the CNS compliance.

Investigating canine cervical sensitivity with an electronic von Frey aesthesiometer: a novel method of assessing syringomyelia-associated neuropathic pain. Heather Williams, Sandra Sanchis, Ludovic Pelligand, Holger Volk, Joanna Murrell, Nicolas Granger. J. Small Anim. Pract. May 2016;57(Suppl. 1):40-41. Quote: J. Small Anim. Pract. May 2016;57(Suppl. 1):40-41. Quote: Objective: To establish that the electronic von Frey aesthesiometer (eVF) may be used to quantify cervical skin sensitivity in Cavalier King Charles Spaniels (CKCS). Background: Cervical syringomyelia affects 70% of CKCS >6 years old, leading to neuropathic pain. Neuropathic pain diagnosis is based on subjective clinical assessment, with no objective measures currently available. The eVF allows application of increasing pressure onto the skin via a non-invasive plastic tip, until the dog responds (i.e. demonstrating skin sensitivity threshold). The eVF screen displays the pressure applied in grams. Study design: Two-centre prospective observational study, ethically covered. Methods: CKCS, presenting for chronic neck scratching and/or suspected neck hypersensitivity, undergoing cervical MRI were recruited. Following acclimatisation, the eVF, unseen by the standing dog, was applied perpendicular to the skin by an investigator blinded to the eVF display. The pressure obtained at the point of a behavioural response was recorded on three consecutive times per cervical test site bilaterally, with the lowest value used for analysis. Test sites were: (i) caudal to the atlas (C2); and (ii) cranial to the shoulder (C4). A control reading was taken from the dorsal aspect of the right 3rd–4th metatarsal region, with the dog in left lateral recumbency. MRI of the caudal fossa and cervical spinal cord followed eVF testing. Results: Data were normally distributed. Of 12 CKCS tested, the mean (standard deviation) skin sensitivity was: (i) at C2 229.1 g (77.9) and C2 234.8 g (55.1 (right/left respectively); at C4 275.5 g (59.5) and C4 273.5 g (91.1) (right/left respectively); and (iii) at the metatarsus region 268.3 g (113.9). One way ANOVA did not reveal differences between test sites (P = 0.475, F = 0.891), possibly due to the low cohort size at this stage in the study. We will recruit 15 dogs/group/centre, grouped by syringomyelia status (syringomyelia-free, asymptomatic, symptomatic) before completing further analysis. Conclusion: Subjective differences between test sites (with C4 having a higher skin sensitivity threshold relative to C2) suggest that the eVF may be able to discriminate differences in skin sensitivity between dogs, but these are not statistically different with the current cohort. We propose here a novel bedside eVF testing protocol to quantify neck pain in CKCS with neuropathic pain and will report further findings based upon a larger cohort of CKCS with/without syringomyelia once recruitment is complete.

Scratching that itch – elucidating the spinal cord injury which causes reflex “phantom” scratching in canine syringomyelia. Zoe R. Nalborczyk, Angus K. McFadyen, Jelena Jovanovik, Anna Tauro, Colin J. Driver, Noel Fitzpatrick, Susan P. Knower, Clare Rusbridge. Chloe Cross, Susan P. Knower, Angus K. Mcfayden, Jelena Jovanovik, Anna Tauro, Colin J Driver, Noel Fitzpatrick, Clare Rusbridge. J. Small Anim. Pract. May 2016;57(Supp S1):60-65. Aims of study: Syringomyelia (SM) is characterised by fluid filled cavities in the spinal cord. A classic sign of severe SM is a tendency to scratch towards one shoulder referred to as “phantom scratching”. Stimulation of neck skin induces a rhythmic scratching action of the ipsilateral limb. Although easy to describe, the mechanism behind this action is less easy to elucidate. A popular explanation is that the dogs experience alloknesis (itch evoked by lightly touching the surrounding skin) or paraesthesia (a spontaneous or evoked sensation). However if affected dogs experience unusual sensations why do they make little or no skin contact? SM phantom scratching is similar to fictive scratch which develops a few months after transection of the caudal cervical spinal cord. In fictive scratch, stimulation of a skin receptive field results in a reflex scratching action due to hyperactivity of the scratching central pattern generator (CPG) i.e. neural circuits controlling a stereotyped sequence of muscle contractions. The similarity to fictive scratch suggests commonality of neural pathways. In this project we investigate the neuroanatomical site that relates to phantom scratching. We first investigate the hypothesis that phenomenon of phantom scratching is associated with a large dorsolateral syrinx in the upper cervical spinal cord segments. We then looked for an association to damage in other areas of the cervical spinal cord and investigated the hypothesis that phantom scratching is not just associated with a dorsolateral syrinx but one that extends to the superficial dorsal horn (SDH). Methods: Medical records from a two year period were searched for Cavalier King Charles Spaniels that had magnetic resonance imaging and diagnosis of clinical SM. The cohort was divided into SM with phantom scratching (19 dogs) and SM but no phantom scratching (18 dogs). The MRI studies were anonymised, randomised and viewed in EFILM TM. For each transverse image the maximum perpendicular dimensions of the syrinx in each spinal cord quadrant was determined. Visual assessment was made as to whether the syrinx extended to the SDH. Results: The study found that phantom scratching is associated with a large dorsolateral syrinx that extends to the SDH in the C3-C6 spinal segments (C2-C5 vertebrae). The study did not find an association to damage of other areas of cervical spinal cord. Conclusion: Phantom scratching in the dog is associated with a large syrinx that extends to the SDH in the C3-C6 spinal segments. We propose that phantom scratching is due to damage to projection neurons in lamina I of the SDH with consequent reduced descending inhibition to the lumbosacral scratching CPG. Drugs affecting SDH targets may be useful for management of phantom scratching. If a dog has SM extending to the SDH then it is at risk for phantom scratching. If an itchy SM affected dog has no SDH involvement then alternative explanations for scratching (e.g. allergic skin disease) should be investigated. (See also this November 2017 article.)

Forebrain conformation changes in Chiari-like malformation. Chloe Cross, Susan P. Knower, Angus K. McFayden, Jelena Jovanovik, Anna Tauro, Colin J. Driver, Noel Fitzpatrick, Clare Rusbridge. J. Small Anim. Pract. May 2016;57(Suppl. 1):63-64. Quote: Aims of study: Chiari-like Malformation (CM) is a caudal fossa and craniocervical junction disorder resulting in cerebrospinal fluid pathway obstruction and variable syringomyelia (SM). Recent studies suggest that conformational changes are not confined to the hindbrain and that the entire skull base is foreshortened. Insufficient room for the forebrain may contribute to caudal displacement and overcrowding of the hindbrain. The olfactory bulbs (OB) are ventrally orientated in brachycephalic dogs; it has been suggested that this may be more extreme in CM. Recently genetic studies have suggested a candidate gene Sall-1 for canine CM. Sall-1 deficiency in mice is associated with decreased OB size and defects in the human orthologue can be associated with skull abnormalities. We hypothesise Cavalier King Charles Spaniels (CKCS) with CM and SM have smaller and more ventrally orientated OB with rostral forebrain flattening. We compared OB size, angulation between the OB and the hard palate and two measurements that represent flattening of the rostral forebrain from 5 phenotypic groups. Methods: Medical records from a 2 year period were searched for CKCS that had brain magnetic resonance imaging (MRI) and neurological assessment. The cohort was divided as follows: SM with phantom scratching (15 dogs); clinical SM (e.g. pain) but no phantom scratching (17 dogs); behavioural signs of pain with CM but no SM (25 dogs); CKCS with no SM and no behavioural signs of pain or scratching (13 dogs). In addition medical records were searched for dogs in the 5–15kg weight range with normal brain MRI (19 dogs including 5 brachycephalic). The MRI studies were anonymised, randomised and viewed in EFILM TM. 5 measurements were taken from the T2W mid-sagittal brain MRI: the OB length and height (product represented OB size), angulation between the dorsal OB and the frontal lobe (bottom angle), angulation between the frontal and parietal lobes (top angle) and angulation between the OB and hard palate (OB angle). Results: There was a trend for decreasing mean OB size with increasing CMSM phenotype severity (SM-scratchers < SM non-scratchers < CM-pain < CKCS-control <other breed control) However post hoc analysis, Bonferroni, indicated that only “other-breed-control” was significantly different from the CMSM groups but was not significantly different from “CKCS control”. ANOVA analysis for OB, bottom and top angle did not reveal a statistically significant difference between the groups however for OB angle there was an apparent separation between the control and CMSM groups suggesting a trend towards more ventrally orientated OB with increasing CMSM phenotype severity. Conclusion: This study suggests that CM should be considered a more global brain and skull conformational disorder with features of extreme brachycephaly including smaller more ventrally orientated OB however further work is required and the measurement technique has been refined for future studies. We recommend that future studies into MRI conformation of CM and SM uses rigorous phenotyping based on clinical signs and age.

In vitro comparative evaluation and stability studies of different brands of pregabalin (75 mg) capsules marketed in Karachi, Pakistan: A case study. Muhammad Arif Asghar, Syed Baqir Shayum Naqvi. Sci.Int.(Lahore). May 2016;28(3):3091-3096. Quote: Pregabalin is a drug of choice for the treatment of epilepsy. Several brands are available in the market which makes it difficult to select the safe, effective and economic one. Therefore, the current study was designed to evaluate and compare the quality and physicochemical characteristics of six different pharmaceutical brands of Pregabalin (75 mg) capsules available in the pharmacies of Karachi, Pakistan. The comparison was based on different parameters such as, price, uniformity of dosage unit, disintegration time, dissolution assessment, chemical assay and stability of Pregabalin using standard methods. The result showed that almost all brands of Pregabalin are within the limits of manufacturers claim and meet USP/BP specifications. However, statistical calculations and similarity factor (f2) studies also revealed that all brands are pharmaceutically equivalent in their quality aspects. On the basis of achieved results, it was concluded that the cost-effective brands of Pregabalin should be utilized for the treatment of epilepsy.

Longitudinal Study of the Relationship among Craniocervical Morphology, Clinical Progression, and Syringomyelia in a Cohort of Cavalier King Charles Spaniels. S. Cerda-Gonzalez, N.J. Olby, E.H. Griffith. J. Vet. Int. Med. June 2016. Quote: Background: Craniocervical junction (CCJ) anomalies and secondary syringomyelia are commonly diagnosed in Cavalier King Charles spaniel (CKCS). Familiarity with the natural history of these abnormalities is vital to understanding the disease syndrome. Objective: To evaluate magnetic resonance imaging (MRI) predictors of worsening clinical signs, syringomyelia, and morphology in CKCS longitudinally. Animals: Fifty-four client-owned CKCS, 5–13 years old; 50% currently symptomatic. Methods: Longitudinal observational study. We enrolled CKCS with an MRI of the CCJ performed ≥3 years earlier. We used questionnaires and neurologic examinations to grade initial and current clinical status. Dogs that could be anesthetized were reimaged. Morphologic assessments included the presence and severity of: Chiari-like malformations, medullary position, atlantooccipital overlapping (AOO), dorsal atlantoaxial bands, and syringomyelia. Cranial cavity volumes and foramen magnum height were measured. Results: Clinical status was evaluated in 54 dogs; 36/54 were reimaged. Mean follow-up was 71 months. Of initially asymptomatic dogs, 32% were symptomatic at re-evaluation. Of initially symptomatic dogs, 56% had worsened; 13% had improved with medical management. The morphology of the CCJ at initial imaging did not predict development of either new or worsened signs or syringomyelia by the time of re-evaluation. Conclusion: Craniocervical junction anomalies assessed in this study did not appear predictive of future clinical status or syringomyelia in our cohort. The impacts of syringomyelia, AOO, and atlantoaxial bands on future clinical status merit further study in larger groups of CKCS. Clinical progression in our cohort of medically managed CKCS did not differ substantially from published reports of those treated surgically.

Differential diagnosis of vertebral spinous process deviations in archaeological and modern domestic dogs. Dennis F. Lawler, Chris Widga, David A. Rubin, Jennifer A. Reetz, Richard H. Evans, Basil P. Tangredi, Richard M. Thomas, Terrence J. Martin, Charles Hildebolt, Kirk Smith, Daniel Leib, Jill E. Sackman, James G. Avery, Gail K. Smith. J. Archaeological Science: Reports. July 2016. Quote: Paleopathological study of domestic animal remains can elucidate human-domesticate relationships, when all reasonable differential diagnoses are considered. Deviated spinous processes found on ancient domesticated dog vertebrae have been assumed to result from pack burdens, although consideration of diagnostic alternatives has been unclear. To more thoroughly assess the potential significance of these features, we first generated an extensive differential diagnosis of potential causes. Broad causal categories included: (i) morphological; (ii) infectious; (iii) taphonomic; (iv) life history (in utero to death), with numerous subcategories that sometimes overlap. We then evaluated these possibilities through an observational and radiology study of 15 ancient deliberate domestic dog burials (191 vertebrae) from the midwestern USA, dating between 10,130 and 200 years ago. Archaeological specimens from the UK were included to evaluate for geographic uniqueness of our observations. We characterized deviations of spinous processes of cervical (n = 74), thoracic (n = 51), lumbar (n = 60), and sacral (n = 6) vertebrae. Affected spinous processes were found in 34% of cervical vertebrae, 63% of thoracic vertebrae, 78% of lumbar vertebrae, and 50% of sacral vertebrae. Four types of spinous process deviations were observed: (a) lateral leaning from the base but not otherwise deviated; (b) lateral curving at some point above the base; (c) bowing because of multiple curves; and (d) torsion along the vertical axis. Computed tomography and micro-computed tomography were essential tools for establishing differential diagnoses. Highlights: Deviated vertebral spinous processes in dogs have been attributed historically to use as pack animals. A differential diagnosis for deviated spinous processes in domesticated dogs is presented. Observational and imaging studies indicate that deviated vertebral spinous processes have complex origins. Computed tomography and micro-computed tomography were essential tools for establishing differential diagnoses. ... Syringomyelia is a painful condition caused by a large, long, or asymmetrical syrinx in the cervical spinal cord, and malformation of the caudal occipital bone leads to cerebellar crowding and herniation of brain tissue, obstructing normal flow of cerebrospinal fluid.

Dogs attending primary-care practice in England with clinical signs suggestive of Chiari-like malformation / syringomyelia. Sanchis-Mora S, Pelligand L, Thomas CL, Volk HA, Abeyesinghe SM, Brodbelt DC, Church DB, Thomson PC, McGreevy PD, O'Neill DG. Vet. Rec. October 2016;179(17). Quote: The study population included all dogs [187,326 dogs] within the VetCompass Programme (September 1, 2009 - April 29, 2014). ... Ninety-three [93] symptomatic CM/SM cases met the case definition, giving a period prevalence overall of 0.05 per cent. Of these cases, 34 dogs (36.6 per cent) were female, 60 dogs (64.5 per cent) were neutered and 63 dogs (67.7 per cent) were insured. The most commonly affected breed overall was the Cavalier King Charles Spaniel (CKCS), accounting for 65 (69.9 per cent) of the case dogs. ... Figure 2The period prevalence in the CKCS was 1.6 per cent [out of a total of 4046 CKCSs]. ... Of these overall cases, there were 29 (44.6 per cent) females, 42 (64.6 per cent) neutered and 44 (67.7 per cent) insured CKCSs. Among the cases, 34 (52.3 per cent) were Blenheim, eight (12.3 per cent) ruby, three (4.6 per cent) black and tan and 20 (30.8 per cent) tricolour. During the study period, 11 of the 65 symptomatic CKCSs were euthanased/died (27.7 per cent). Nine of symptomatic CKCSs (10.8 per cent) died directly as a result of CM/SM. ... [T]he current study failed to identify a significant association between colour coat and symptomatic CM/SM diagnosis. Similarly, age did not statistically affect symptomatic diagnosis in the CKCS ... Other breeds affected included the King Charles Spaniel (KCS) (16 dogs, 17.2 per cent); crossbred (three dogs, 3.2 per cent); Chihuahua and Yorkshire Terrier (two dogs each, 2.2 per cent) and the Pug, Affenpinscher, Jack Russell terrier, Pomeranian and Shih Tzu (one dog each, 1.1 per cent). Of the three recorded crossbred CM/SM cases, two were recorded as being partly CKCS. ... Insured dogs had 4.6 times the odds of having a diagnosis of CM/SM compared with uninsured dogs. ... In the 93 cases, the most common sign reported for CM/SM was pain (67 dogs, 72 per cent). The most common manifestations were phantom scratching (36 dogs, 38.7 per cent), spontaneous yelping (27 dogs, 29 per cent), neck pain on palpation (16 dogs, 17.2 per cent) and provoked yelping, for example, vocalisation when picked up or touched (15 dogs, 16.1 per cent). ... Treatment data were available for 89 of the 93 affected dogs. Seventy-two dogs (77.4 per cent) received one or more drugs for treatment of CM/SM, and 17 dogs (20.4 per cent) were unmedicated. Gabapentin, NSAIDs and corticosteroids were the most commonly prescribed treatments for CM/SM administered to 48 dogs (67 per cent), 47 dogs (65 per cent) and 23 dogs (32 per cent), respectively. Of the 17 unmedicated dogs, six were reported to have pain and six were reported to show only scratching behaviour (35.2 per cent each). Of the 72 medicated dogs, 64 (88.8 per cent) were reported to show either a partial or a full response to medication, while the remaining nine dogs (12.5 per cent) were reported to have not improved after treatment. Figure 3

Two dogs (2.1 per cent of cases) underwent surgery for CM/SM but the outcomes of surgery were not recorded. During the study period, 23 of the 93 case dogs overall were euthanased/died (24.8 per cent). Of the 93 case dogs, nine (9.8 per cent) died or were euthanased as a result of CM/SM. ... Multivariable analysis identified three risk factors associated with CM/SM: breed, age and insurance. ... Dogs aged over five years had 2.7 times the odds of diagnosis of symptomatic CM/SM compared with dogs of less than one year of age. Insured dogs had 4.6 times the odds of CM/SM compared with uninsured dogs. ... Analgesics were prescribed to 72 (77.4 per cent) of the symptomatic dogs. ... Underestimation of the true prevalence: Diagnosis of CM/SM generally requires an MRI. However, this is a major limitation in primary-care practice. A significant proportion of dogs in this study were excluded because a clinical diagnosis was not made despite possible signs of CM/SM being present and because clinical signs could be confounded with other diagnosed diseases. This is an important source of underestimation of the true prevalence. It is also a concern as many dogs will not reach a final diagnosis and therefore will not be appropriately treated. This leads to a decrease in welfare of these patients. Some dogs have been diagnosed without MRI and therefore false positives may have been included. ... The increased diagnosis level recorded in insured animals suggests that financial and other constraints on diagnostic procedures may have allowed the true prevalence of CM/SM in the overall population to be underestimated. ... This study may help to inform clinicians about the clinical relevance and the need for improved awareness of clinical signs, particularly in high-risk breeds, to optimise the management of CM/SM in primary-care practice.

Acupuncture as an aid to treatment of Chiari-like malformation (CM)/syringomyelia (SM) in a Cavalier King Charles spaniel (CKCS). Donal Joseph O'Leary. Vet. Rec. Case Rept. September 2016;4(2). Quote: Syringomyelia associated with Chiari-like malformation is a common inherited condition in the Cavalier King Charles spaniel (CKCS) and often leads to debilitating clinical signs. Both conventional surgical and medical intervention in veterinary medicine tries to address the pain associated with the condition. The most common symptoms associated with Chiari-like malformation in human beings are neck pain and suboccipital headaches. ... This patient exhibited signs which suggested it was also suffering from headaches. It often presented with a frowning expression and during these times intensely disliked being touched, rubbed or patted on the head. Acupuncture had a definite positive effect on this patient with reductions in all the signs including the signs of phantom scratching and vocalisation. ... The patient exhibited signs which suggested it was suffering from similar clinical signs and acupuncture was used successfully as an aid to control these clinical signs along with conventional medical treatment. ... This patient exhibited both back and neck pain and evidence that it was suffering from headaches is also strong. It is therefore likely that acupuncture has positive effects on these also. ... The dog has now been coming for acupuncture for five years. The owner reports that it has a significant positive effect on both its demeanour and on the clinical signs. The squinting/ ‘pained’ expression is virtually eliminated when the dog comes regularly (three-week interval) for acupuncture.

Before acupunctureAfter acupunture


Clinical and Diagnostic Imaging Features of Brain Herniation in Dogs and Cats. M.J. Lewis, N.J. Olby, P.J. Early, C.L. Mariani, K.R. Muñana, G.S. Seiler, E.H. Griffith. J. Vet. Internal Med. September 2016;30(5):1672-1680. Quote: Background: Quantification of brain herniation on MRI and its immediate clinical implications are poorly described. Objectives: Define the normal position of caudal fossa structures on brain MRIs in dogs and cats utilizing morphometry, compare this to dogs and cats with caudal transtentorial herniation (CTH), foramen magnum herniation (FMH) or both identified on MRI, and investigate associations between herniation severity, clinical signs, and 24-hour outcome. Animals: Ninety-two controls (66 dogs, 26 cats), 119 cases with herniation (88 dogs, 31 cats). Methods: Retrospective case series. The MRI database was searched for controls with normal brain anatomy and cases with brain herniation. Morphometry in controls established TTX (transtentorial to rostroventral cerebellum) to quantify CTH and FMX (caudoventral cerebellum to foramen magnum) to quantify FMH. Measurements were compared between cases and controls. Correlations with specific clinical variables and outcome were investigated. Results: Measurements in medium/large control dogs versus small dog and cat controls were significantly different (P < .001, TTX: −0.46, −0.305, −0.3, FMX: 0.695, 0.27, 0.25, respectively). 119/1564 (7.6%) cases that underwent brain imaging had brain herniation. TTX and FMX were significantly different between controls and cases with CTH or FMH (P < .001). 67/89 (75%) cases with supratentorial lesions had no signs directly attributable to herniation. 71/119 (60%) had a normal anesthetic recovery. TTX was significantly associated with 24-hour survival (P < .001). Conclusions and clinical importance: Brain herniation can be quantified on MRI. Clinical signs directly attributable to brain herniation commonly are absent, and more severe CTH based on TTX is associated with a worse short-term outcome.

Perfusion-weighted Magnetic Resonance Imaging of Brachycephalic Dogs with Ventriculomegaly. M. J. Schmidt, A. Hartmann, K. H. von Pückler, L. Hähnsen, N. Ondreka. Vet. Rad. & Ultra. October 2016;57(6):646-669. Quote: Introduction: It has been shown that ventriculomegaly in dogs is associated with a loss of periventricular white matter comparable to clinical relevant internal hydrocephalus or normal pressure hydrocephalus (NPH). The pathophysiology of ventricular distension is unclear currently. The aim of this study was to compare brain perfusion in dogs with and without ventriculomegaly using perfusion-weighted magnetic resonance imaging to clarify, as to whether abnormal perfusion might be involved in the pathophysiology of ventriculomegaly. Materials and methods: Perfusion was measured in 23 Cavalier King Charles spaniels with ventriculomegaly, 10 healthy Beagle dogs were examined as a control group. Perfusion-weighted images were acquired using a dynamic multishot fast-field echo-EPI in a dorsal plane. Forty acquisitions per slice were acquired. Contrast was automatically injected using an automatic pump (0.2 mmol/kg body weight) in 20 ml crystalloid solution with an injection rate of 5 ml/s. Contrast was given at the 10th acquisition. Perfusion was measured using free-hand regions of interest (ROI) in five brain regions: periventricular white matter, caudate nucleus, parietal cortex, hippocampus, and thalamus using the STROKETOOL software tool. Time to peak (TTP), regional cerebral blood flow (rCBF), regional blood volume (rCBV), and mean transit time (MTT) was measured. Intraobserver variability was measured using kappa statistics. Differences between groups were tested using Mann–Whitney U-tests. Significance level was <0.05. Results: rCBF and rCBV were significantly lower in the periventricular white matter of the dogs with ventriculomegaly compared to control dogs (P < 0.001) but not for the other ROIs. Kappa statistics revealed substantial agreement between measurements (0.82). Discussion: Based on the differences in periventricular perfusion ventriculomegaly should be interpreted as a form of NPH as suggested previously. The impaired perfusion might be the reason for the reduced white matter volume in these dogs. This has been shown in laboratory rodents with experimentally induced hydrocephalus and humans with NPH. Cognitive studies should be conducted to investigate a possible impairment of memory, learning, and spatial orientation as present in humans with NPH.

Utility of the Electronic Von Frey Aesthesiometer to Quantify Cervical Skin Sensitivity in Dogs with Syringomyelia. H. Williams, S. Sanchis, H. A. Volk, L. Pelligand, J. Murrell, N. Granger. J. Vet. Int. Med. November 2016;30(6):1937. Quote: Only 35% of Cavalier King Charles Spaniels (CKCS) with syringomyelia display pain-associated behaviours, but we suspect that a greater proportion experience pain. An objective means of detecting pain in these dogs is lacking. Electronic von Frey aesthesiometer (eVF) testing consists of applying pressure onto the skin via a plastic tip. The pressure value is displayed electronically. Exceeding a certain pressure, defined as the skin sensitivity threshold, triggers a behavioural response from the dog. We conducted an ethically-approved, two-centre prospective observational study to assess whether the eVF could differentiate, based on cervical skin sensitivity threshold, CKCS with: (i) syringomyelia and clinical signs (syringomyelia-symptomatic – SM-S); (ii) syringomyelia without clinical signs (syringomyelia-asymptomatic – SM-A); and (iii) no syringomyelia (syringomyelia-free - SM-F). All dogs had cervical and caudal fossa magnetic resonance imaging. Following acclimatisation, the eVF was applied by an investigator blinded to the eVF display and skin sensitivity threshold recorded at C2 and C4 vertebrae bilaterally (three measures per site) and at the right dorsal metatarsal (RH). Data were analysed with multiple analysis of variance including fixed factors (centre, medication, group) and covariates (RH, age, clinical signs duration). Seventy CKCS were recruited into: SM-S (37), SM-A (15), SM-F (18). No difference in sensitivity was found between groups, except for the RH when analysed as a covariate (P = 0.031) but not post-hoc as a dependent variable (P = 0.885). Split plot analysis of variance demonstrated differences between cervical sites, independently of syringomyelia group (P < 0.001). In conclusion, eVF assessment of skin sensitivity does not differ significantly by syringomyelia status.

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2017

Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel. Susan P. Knowler, Chloe Cross, Sandra Griffiths, Angus K. McFadyen, Jelena Jovanovik, Anna Tauro, Zoha Kibar, Colin J. Driver, Roberto M. La Ragione, Clare Rusbridge. PLOS One. January 2017. Quote: Objectives: To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel [CKCS] using morphometric [the quantitative analysis of form, a concept that encompasses size and shape] measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods: This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and olfactory lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results: Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. Figure 6The Control cohort [31 CKCS in the hindbrain study (HBS) and 16 CKCSs in the whole brain study (WBS)] had the most natural, wolf-like, skull conformation in terms of ellipticity. The CM pain cohort [28 CKCSs in HBS and 25 CKCSs in WBS] was characterised by increased brachycephaly with greatest rostral forebrain flattening, shortest basicranium and compensatory cranial height. However, in this cohort, an increased distance between the occiput and atlas provided fewer impediments to CSF dynamics at the foramen magnum and reduced the risk for SM. The SM cohort [71 CKCSs in HBS and 31 CKCSs in WBS] exhibited two conformation anomalies. One phenotype variation was influenced by incongruities at the craniocervical junction and increased proximity of the dens producing a ‘concertina’ type flexure with medullary elevation. The other phenotypic variation was influenced by increased brachycephaly resulted in a ‘concertina’ type flexure similar to the CM pain cohort. However, both SM variations were characterised by an apparent reduction in caudal fossa volume which compromised the CSF dynamics in the spinal cord. Conclusion: Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It might identify dogs at risk of SM and CM pain to improve diagnosis and make available a means for screening breeding dogs and provide estimated breeding values. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise the neural parenchyma and impede cerebrospinal fluid flow. (Motion picture highlights the dynamic changes of the skull conformation and brain parenchyma associated with progressive brachycephaly and airorhynchy, shortening of the basicranium and supraoccipital bones and the proximity and angulation of the atlas and dens.)

Craniometric Analysis of the Hindbrain and Craniocervical Junction of Chihuahua, Affenpinscher and Cavalier King Charles Spaniel Dogs With and Without Syringomyelia Secondary to Chiari-Like Malformation.  Susan P. Knowler, Anna-Mariam Kiviranta, Angus K. McFadyen, Tarja S. Jokinen, Roberto M. La Ragione, Clare Rusbridge. PLOS One. January 2017. Quote: Objectives: To characterize and compare the phenotypic variables of the hindbrain and craniocervical junction associated with syringomyelia (SM) in the Chihuahua, Affenpinscher and Cavalier King Charles Spaniel (CKCS). Method: Analysis of 273 T1-weighted mid-sagittal DICOM sequences of the hindbrain and craniocervical junction from 99 Chihuahuas, 42 Affenpinschers and 132 CKCSs. The study compared 22 morphometric features (11 lines, eight angles and three ratios) of dogs with and without SM using refined techniques based on previous studies of the Griffon Bruxellois (GB) using Discriminant Function Analysis and ANOVA with post-hoc corrections. Results: The analysis identified 14/22 significant traits for SM in the three dog breeds, five of which were identical to those reported for the GB and suggest inclusion of a common aetiology. One ratio, caudal fossa height to the length of the skull base extended to an imaginary point of alignment between the atlas and supraoccipital bones, was common to all three breeds (p values 0.029 to <0.001). Associated with SM were a reduced occipital crest and two acute changes in angulation i) ‘sphenoid flexure’ at the spheno-occipital synchondrosis ii) ‘cervical flexure’ at the foramen magnum allied with medulla oblongata elevation. Comparing dogs with and without SM, each breed had a unique trait: Chihuahuas had a smaller angle between the dens, atlas and basioccipital bone (p value < 0.001); Affenpinschers had a smaller distance from atlas to dens (p value 0.009); CKCS had a shorter distance between the spheno-occipital synchondrosis and atlas (p value 0.007). ... Ten of the fourteen significant variables were found in the CKCS with one, line ac [see diagram below], unique to the breed. Line ac indicates the proximity of the sphenooccipital synchondrosis to the atlas bone. This study confirms the findings of others that the CKCS with SM have a reduced caudal fossa size a presumed consequence of early closure of the spheno-occipital and possibly other cranial sutures. Compared to other breeds including the GB, the CKCS has considerably greater incidence of cerebellar deformation by the supra-occipital bone and vermis herniation. These findings and the coexistence of occipital dysplasia and hypoplasia suggest that the CKCS may have additional predisposing risk factors for SM compared to the other breeds. ... Conclusion: The selected morphometries successfully characterised conformational changes in the brain and craniocervical junction that might form the basis of a diagnostic tool for all breeds. The severity of SM involved a spectrum of abnormalities, incurred by changes in both angulation and size that could alter neural parenchyma compliance and/or impede cerebrospinal fluid channels. (Figure 7, below,  links what is happening in the front and back of the skull.)

Figure 7

Prevalence of dorsal notch and variations in the foramen magnum shape in dogs of different breeds and morphotypes. Marta Kupczyńska, Norbert Czubaj, Karolina Barszcz, Wojciech Sokołowski, Michał Czopowicz, Halina Purzyc, Małgorzata Dzierzęcka, Wojciech Kinda, Zdzisław Kiełbowicz. Biolgia. February 2017;72(2):230-237. Quote: The study evaluated shape of the foramen magnum (FM) in dog with regard to its constitutional type (small, medium and large breeds) and morphotype (brachycephalic, mesaticephalic and dolichocephalic dogs). ... Currently, there is a discussion among researchers whether to consider occipital dysplasia as part of the normal morphology of the occipital bone that occurs mainly in small breeds (including ... the Cavalier King Charles Spaniel) ... Nevertheless, it has to be stated here that problems concerning so called “occipital area” are most often found in Cavalier King Charles Spaniels. ... We used multi-slice CT scanner to examine occipital area of 138 purebreds dogs. Two studied groups could be distinguished – living animals undergoing standard diagnostic CT procedure (n = 47) and macerated skulls of euthanized dogs (n = 91). Morphometric analysis was focused on presence of dorsal notch within foramen magnum. This anatomical feature was present in 33.3% of examined dogs. It was more often observed in small size dogs (70%) and those of brachycephalic morphotype (94.1%). For the first time dorsal notch was noted in breeds such as French Bulldog, Fox Terrier, Keeshond, Standard Schnauzer, English Bulldog, Cocker Spaniel, Boxer and Rottweiler. We distinguished four different shape of FM: oval, pentagonal, rhomboid and circular. Most common FM shape was oval (41 dogs; 45%) whereas circular type was least observed (5 dogs; 5.5%). The pentagonal shape was noticed in 27 specimens (29.7%) and the rhomboid shape in 18 dogs (19.8%). Authors conclude that dorsal notch is not pathology and should be considered a morphological variation within the normal anatomy. Results presented in this study should be taken into account during interpretation of the CT images of the craniocervical junction.

Cavalier King Charles Spaniels with Chiari-like malformation and Syringomyelia have increased variability of spatio-temporal gait characteristics. Olsen E, Suiter EJ, Pfau T, McGonnell IM, Matiasek K, Giejda A, Volk HA. BMC Vet Res. June 2017;13(1):159. Quote: Background: Chiari-like malformation in the Cavalier King Charles Spaniel is a herniation of the cerebellum and brainstem into or through the foramen magnum. This condition predisposes to Syringomyelia; fluid filled syrinxes within the spinal cord. The resulting pathology in spinal cord and cerebellum create neuropathic pain and changes in gait. This study aims to quantify the changes in gait for Cavalier King Charles Spaniel with Chiari-like malformation and Syringomyelia. Methods: We compared Cavalier King Charles Spaniel with Chiari-like malformation with (n = 9) and without (n = 8) Syringomyelia to Border Terriers (n = 8). Two video cameras and manual tracking was used to quantify gait parameters. Results & Conclusions: We found a significant increase in coefficient of variation for the spatio-temporal characteristics and ipsilateral distance between paws and a wider base of support in the thoracic limbs but not in the pelvic limbs for Cavalier King Charles Spaniels compared with the border terrier.

Syringomyelie – neue Therapieoption am Horizont? (Syringomyelia - new therapy option on the horizon) Stefanie Kruppke. Veterinär Spiegel. June 2017;27(02): 53-55. Quote (translated from German): The patients: Two Cavalier King Charles Spaniels were presented with the main symptom "nonspecific itching" (male, 8 and 4 years old) in practice. A complete dermatological clarification including cytology and skin scraping was carried out beforehand. In addition, parasitic therapy was performed with a combination preparation of 400 mg imidacloprid and 100 mg moxidectin as well as therapy with afoxolans to exclude a parasitic itching. Afterwards magnetic resonance tomography was diagnosed with chiari-like malformations and syringomyelia. The initiation of gabapentin therapy (10 mg / kg every 8 hours) as a possible therapy described in the corresponding literature showed only moderate results and an unsatisfactory result. New therapy option? Since these therapeutic approaches do not always lead to a satisfactory result, new approaches have been sought to help these patients. Since the itching is a neuropathically induced itching, a preparation with the active ingredient oclacitinib was used, which in the case of allergic dermatitis inhibits itching in the neurological range. An important element in inflammation and itching symptoms is the enzyme Januskinase. The immune modulator Oclacitinib [Apoquel] inhibits this enzyme and thus the inflammatory reactions and itching in atopic dermatitis. In the two Cavalier King Charles Spaniels presented, a therapy with oclacitinib was initiated in the standard dose, which is recommended for atopic dermatitis (0.4-0.6 mg / kg 2 × daily for 14 days, then 1 × daily administration). The use of the immunomodulator Oclacitinib as an "off-label use" can greatly assist the animal and owner in cases of tormenting itching and return both a piece of life quality despite a serious diagnosis. Result and conclusion: After only 2 days the itching is clearly reduced, no scratching behavior can be observed after 1 week and the owners report a generally improved general condition. Both patients are taking the drug for a year now and are clinically inconspicuous, side effects have not occurred. This case report has yet to be proved by larger studies, so that the exact mechanism of action can be investigated. However, this drug may eventually serve as a promising therapy for syringomyelia after further studies. Of course, there is no authorization for this indication so that it is initially an "off-label use".

Prävalenz der Chiari-ähnlichen Malformation und der Syringomyelie bei Cavalier King Charles Spanieln in der Bundesrepublik Deutschland. Prevalence of Chiari-like malformation and syringomyelia in Cavalier King Charles Spaniels in the Federal Republic of Germany. Miriam Refai, disseration. The Justus Liebig University of Giessen. May 2017. Quote: The aim of the present study was to establish the prevalence of Chiari-like malformation and syringomyelia within the CKCS breed of Germany and to determine whether age and/or sex had a significant influence on the prevalence of syringomyelia. A total of 339 CKCS were available for this study and their age ranged from 2.9 month to 11.2 years. Most of the dogs were asymptomatic and only presented by their owners request for breeding examination using magnetic resonance imaging (MRI). In this study we also included some dogs with clinical signs and MRI, because of a neurologic or non-neurologic disease. Consequently the analysis of the data record is based on the diagnostic findings of asymptomatic as well as symptomatic CKCS. T1- and T2-weighted magnetic resonance images of the head and the cranial cervical spinal cord (to C5 vertebra) were obtained from each participant. The dogs were divided into two groups, “affected” or “non-affected”, whether they suffer from Chiari-like malformation and/or syringomyelia or not. The classification was made in regard to presence or absence of Chiari-like malformation and/or syringomyelia, without any subdivision or graduation of these conditions. Pathomorphological changes consistent with Chiari-like malformation were found in 329 of 339 CKCS. Without consideration of the age, there was an overall prevalence within this tested population of 97.1% of dogs with Chiari-like malformation. 163 of 339 CKCS had a proved evidence of syringomyelia at the point of examination. This finding resulted in an overall prevalence of 48.1% of CKCS with a positive diagnosis of syringomyelia. The outcome of this study revealed that the risk of developing syringomyelia increases with the age of the CKCS. Additionally, it was found that syringomyelia can occur as a late onset disease. The prevalence of dogs, that showed changes consistent with syringomyelia, was 25% within the first year of life, but in CKCS over six years of age the prevalence was already 63.7%. In spite of these findings, sex did not have a significant effect on developing syringomyelia within the participants of this study. Therefore, the inherited genetic defect of syringomyelia does not appear to be sex-linked. The present study confirmed that Chiari-like malformation appears to be ubiquitous in the CKCS breed and that almost half of all dogs within the CKCS population seems to be affected by syringomyelia in Germany. These results support the assumption of other authors that the likelihood of a positive scan for syringomyelia raises with increased age of the CKCS.

Dynamic Susceptibility Contrast Perfusion Magnetic Resonance Imaging Demonstrates Reduced Periventricular Cerebral Blood Flow in Dogs with Ventriculomegaly. Martin J. Schmidt, Malgorzata Kolecka, Robert Kirberger, Antje Hartmann. Vet. Neuro. & Neurosurgery. August 2017; doi: 10.3389/fvets.2017.00137. Quote: The nature of ventriculomegaly in dogs is still a matter of debate. Signs of increased intraventricular pressure and atrophy of the cerebral white matter have been found in dogs with ventriculomegaly, which would imply increased intraventricular pressure and, therefore, a pathological condition, i.e., to some extent. Reduced periventricular blood flow was found in people with high elevated intraventricular pressure. The aim of this study was to compare periventricular brain perfusion in dogs with and without ventriculomegaly using perfusion weighted-magnetic-resonance-imaging to clarify as to whether ventriculomegaly might be associated with an increase in intraventricular pressure. Perfusion was measured in 32 Cavalier King Charles spaniels (CKCS) with ventriculomegaly, 10 CKCSs were examined as a control group. Cerebral blood flow (CBF) was measured using free-hand regions of interest (ROI) in five brain regions: periventricular white matter, caudate nucleus, parietal cortex, hippocampus, and thalamus. CBF was significantly lower in the periventricular white matter of the dogs with ventriculomegaly but not in the other ROIs. Reduction of periventricular CBF might imply increase of intraventricular pressure in ventriculomegaly. ... Cerebral blood flow can be reduced in periventricular white matter in CKCSs with ventriculomegaly, which makes some increase of intraventricular pressure likely.

Syringomyelia and Craniocervical Junction Abnormalities in Chihuahuas. A.-M. Kiviranta, C. Rusbridge, O. Laitinen-Vapaavuori, A. Hielm-Björkman, A.K. Lappalainen, S.P. Knowler, T.S. Jokinen. J. Vet. Int. Med. September 2017. Background: Chiari-like malformation (CM) and syringomyelia (SM) are widely reported in Cavalier King Charles Spaniels and Griffon Bruxellois dogs. Increasing evidence indicates that CM and SM also occur in other small and toy breed dogs, such as Chihuahuas. Objectives: To describe the presence of SM and craniocervical junction (CCJ) abnormalities in Chihuahuas and to evaluate the possible association of CCJ abnormalities with SM. To describe CM/SM-related clinical signs and neurologic deficits and to investigate the association of CM/SM-related clinical signs with signalment, SM, or CCJ abnormalities. Animals: Fifty-three client-owned Chihuahuas. Methods: Prospective study. Questionnaire analyses and physical and neurologic examinations were obtained before magnetic resonance and computed tomography imaging. Images were evaluated for the presence of SM, CM, and atlantooccipital overlapping. Additionally, medullary kinking, dorsal spinal cord compression, and their sum indices were calculated. Results: Scratching was the most common CM/SM-related clinical sign and decreased postural reaction the most common neurologic deficit in 73 and 87% of dogs, respectively. Chiari-like malformation and SM were present in 100 and 38% of dogs, respectively. Syringomyelia was associated with the presence of CM/SM-related clinical signs (P = 0.034), and medullary kinking and sum indices were higher in dogs with clinical signs (P = 0.016 and P = 0.007, respectively). Conclusions and Clinical Importance: Syringomyelia and CCJ abnormalities are prevalent in Chihuahuas. Syringomyelia was an important factor for the presence of CM/SM-related clinical signs, but many dogs suffered from similar clinical signs without being affected by SM, highlighting the clinical importance of CCJ abnormalities in Chihuahuas.

Twelve years of chiari-like malformation and syringomyelia scanning in Cavalier King Charles Spaniels in the Netherlands: Towards a more precise phenotype. Wijnrocx K, Van Bruggen LWL, Eggelmeijer W, Noorman E, Jacques A, Buys N, Janssens S, Mandigers PJJ. PLoS One. September 2017;12(9). Quote: Chiari-like malformation (CM), syringomyelia (SM) and middle ear effusion (also called PSOM) are three conditions that frequently occur in Cavalier King Charles Spaniels (CKCS). Both CM and SM are currently screened in the Netherlands prior to breeding and are graded according to the British Veterinary Association's Kennel Club (BVA/KC) scheme. This study evaluated the prevalence and estimated genetic parameter of CM, SM and middle ear effusion from 12 years of screening results. For SM, the classical method using the BVA/KC scheme, was compared with exact measuring of the central canal dilation. For CM, the BVA/KC scheme was compared with a more detailed scheme. Next to this the presence of microchip artifacts was assessed. 1249 screening of 1020 dogs were re-evaluated. Results indicated the presence of CM in all dogs, suggesting it has become a breed-specific characteristic. And although different grades of CM were observed, the condition did not deteriorate over time. SM was present in 39% of the dogs and a clear age effect was demonstrated, with SM increasing with age. This emphasizes the importance of screening at appropriate age, since SM can worsen with increasing age. One alternative is to promote repeated measures. The presence of middle ear effusion in this study was 19%-21% for dogs younger than 3 years, and 32%-38% for dogs older than 3 years. In as much as 60%, microchip artifacts were noticed, leading to the recommendation to place microchips in another location in breeds that are susceptible to developing SM. Finally, this study estimated the heritability of CM in this population, due to the lack of phenotypic variance, to be very low at 0.02-0.03. The heritability for SM central canal dilatation to be 0.30, compared to 0.13 for the classical BVA/KC method, using a model including the age effect and the combined effect of veterinary clinic and year of the evaluation. Genetic correlations were rather small, ranging from 0.16-0.33. As a conclusion, screening for SM and CM in the entire population should be maintained, and a selection scheme against SM should be based on estimated breeding values for the exact measurement of the central canal dilatation.

Questionnaire-based Analysis of Owner-reported Scratching and Pain Signs in Cavalier King Charles Spaniels Screened for Chiari-like Malformation and Syringomyelia. C.R. Sparks, S. Cerda-Gonzalez, E.H. Griffith, B.D.X. Lascelles, N.J. Olby. J. Vet. Intern. Med. January 2018;32(1):331–339. Quote: Background: Chiari-like malformation (CM) and syringomyelia (SM) cause a pain syndrome in Cavalier King Charles spaniels (CKCS). Clinical signs are not consistently apparent on neurologic examination, and owner reporting of signs provides vital clinical history. However, owner questionnaires for this disease are not well developed. Objectives: To develop a tool to capture owner-reported clinical signs for use in clinical trials and to compare owner-reported signs with the presence of pain on neurologic examination and SM on magnetic resonance imaging (MRI). Animals: Fifty client-owned CKCS. Methods: Owners completed a questionnaire [linked here] and pain/scratch map [linked here]. Each dog underwent a neurologic examination and craniocervical magnetic resonance imaging (MRI). Questionnaire responses were developed into scores, area of shading for pain/scratch maps was measured, and consistency of responses between these tools was assessed. Owner-reported findings were compared with neurologic examination findings and presence and severity of SM on MRI. Results: Thirty-three dogs were symptomatic and 17 asymptomatic; 30 had SM. ...The most common presenting sign was phantom scratching, occurring in 32 dogs, and the most common sign of pain was crying out when being lifted, occurring in 11 dogs. Figure 1[See Figure 1 at right.] ... Extent of shaded areas on maps positively correlated with questionnaire scores for pain and scratch. Owner-reported findings were not significantly associated with presence or severity of SM or neurologic examination findings. Owner-reported lateralization of signs was significantly associated with SM lateralization. Conclusions: The questionnaire and maps may be useful for clinical trials. Lack of association of owner-reported signs with SM highlights our lack of understanding of the pathophysiology of pain in this disease. ... The conclusion that SM causes pain in CKCS is complicated by the finding that dogs with CM but no SM can show classic signs of neuropathic pain, as illustrated by 10 dogs in our study. Inconsistencies have been described in prior studies as well. These data emphasize the uncertainty surrounding the role of SM in producing signs in these dogs. Indeed, other breeds, such as Yorkshire terriers, commonly have SM yet do not display the same signs. ... To conclude, the full range of signs reported by owners of CKCS includes a variety of manifestations of pain, with phantom scratching as the most commonly reported sign followed by crying out when being lifted. Owner reporting of pain and scratch frequency and severity captured by the [revised final questionnaire, named ChiMPS-T (Chiari-like malformation pain and scratch tool)  linked here] correlates with the owner-reported surface area affected by these signs in their dogs. Neither the scores nor the surface area reported correlated with the presence or severity of SM, highlighting uncertainty on the source of pain in these dogs. Further validation of these tools including responsiveness, test-retest, and discriminatory validity needs to be assessed. The relationship among CM, SM, and pain and scratch in this population of dogs deserves further examination.

MRI characteristics for “phantom” scratching in canine syringomyelia. Zoe R. Nalborczyk, Angus K. McFadyen, Jelena Jovanovik, Anna Tauro, Colin J. Driver, Noel Fitzpatrick, Susan P. Knower, Clare Rusbridge. BMC Vet. Res. November 2017. DOI 10.1186/s12917-017-1258-2. Quote: Background: A classic sign of canine syringomyelia (SM) is scratching towards one shoulder. Using magnetic resonance imaging (MRI) we investigate the spinal cord lesion relating to this phenomenon which has characteristics similar to fictive scratch secondary to spinal cord transection. Medical records were searched for Cavalier King Charles spaniels with a clinical and MRI diagnosis of symptomatic SM associated with Chiari-like malformation (CM). The cohort was divided into SM with phantom scratching (19 dogs) and SM but no phantom scratching (18 dogs). MRI files were anonymised, randomised and viewed in EFILM ™. For each transverse image, the maximum perpendicular dimensions of the syrinx in the dorsal spinal cord quadrants were determined. Visual assessment was made as to whether the syrinx extended to the superficial dorsal horn (SDH). Results: We showed that phantom scratching appears associated with a large dorsolateral syrinx that extends to the SDH in the C3-C6 spinal cord segments (corresponding to C2-C5 vertebrae). Estimated dorsal quadrant syrinx sizes based on the perpendicular diameters were between 2.5 and 9.5 times larger in dogs with phantom scratching, with the largest mean difference p-value being 0.009. Conclusion: SM associated phantom scratching appears associated with MRI findings of a large syrinx extending into the mid cervical SDH. We hypothesise that damage in this region might influence the lumbosacral scratching central pattern generator (CPG). If a scratching SM affected dog does not have a large dorsolateral cervical syrinx with SDH involvement then alternative explanations for scratching should be investigated. (See also this May 2016 abstract.)

Characterisation of chiari-like malformation and secondary syringomyelia in selected toy dog breeds using magnetic resonance imaging. Knowler, S. P. November 2017. Doctoral thesis, Univ. of Surrey. Quote: Chiari-like Malformation (CM) and secondary Syringomyelia (SM) is a complex, debilitating abnormality which compromises the normal cerebrospinal fluid movement of the central nervous system culminating in the development of fluid-containing cavities within the spinal cord and associated with behavioural signs of pain and neurological deficits. The prevalence of asymptomatic CM dogs suggest that cerebellar indentation and impaction may be normal anatomical variations and unsuitable as a definition of CM. Magnetic Resonance Imaging (MRI) remains the definitive means of diagnosing CM/SM and a morphometric technique of quantifying CM and SM on mid-sagittal MRI has been successfully applied and validated in previous studies to a cohort of Griffon Bruxellois (GB) dogs with and without CM and a mixed breed GB family crossed with a mesaticephalic breed (Australian Terrier). Using a refined technique which took account of recent research findings, morphometries using a triangulation of circles, lines and angles were used to ‘map’ MRIs of the whole brain and cervical region in order to quantify the severity of the CM and SM phenotype in the Cavalier King Charles (CKCS). A further morphometric analysis was undertaken to explore brachycephaly and miniaturization as risk factors for CM and SM by comparing their impact in the CKCS, Affenpinscher and Chihuahua breeds. The collective framework of lines and angles generated a unique ‘signature’ for the dog, characterised by “concertina” type flexures demonstrating the combined nature of segregated traits towards the severity in the phenotype. Compared to controls, CKCS with CM pain are characterised by increased brachycephaly and airorhynchy, while significant traits for SM in the three dog breeds included those reported for the GB, suggesting a common aetiology. The characterisation of the CM phenotype provides the possibility of a diagnostic tool for veterinarians and means to assist breeders with mate selection to reduce symptomatic prevalence of CM/SM.

Chiari-like malformation and syringomyelia. Sandra Sanchis Mora, Ludovic Pelligand. Vet. Focus. November 2017;3:29-34. Quote: Key Points: • Chiari-like malformation and syringomyelia are two linked conditions that cause neuropathic pain. • A high proportion of Cavalier King Charles Spaniels are affected, although other (usually small) breeds can also be susceptible. • Clinical signs of neuropathic pain are non- specific, and confirmation of the disease is supported by magnetic resonance imaging. • Treatment options include using a combination of different analgesics, or surgical decompression of the caudal cranial fossa, but owners should be aware that neuropathic pain is challenging to treat and that the main goal is to maintain a good quality of life for the patient.

MRI-based morphometric analysis in relation to Chiari-like malformation in brachycephalic canine breeds. C.R. Gordon, K. Marioni-Henry, P. Amengual, T. Liuti. Vlaams Diergeneeskundig Tijdschrift. December 2017;86:351-360. Quote: The aim of this study was to investigate potential differences and correlations between brain and skull morphology and the clinical signs of brachycephalic dogs with and without Chiari-like malformation (CLM). ... The high prevalence of CLM in the CKCS prohibits a comparison with CLM free dogs within this breed alone. In this study, a strictly brachycephalic study population was utilized for morphometric comparisons between dogs with and without CLM. ... A total of thirty dogs were included in the study, of which five were neutered males, seven intact males, twelve neutered females and six intact females. The breeds represented included the CKCS (16), French bulldog (5), Pug (3), Chihuahua (2), Boxer (2), Staffordshire bull terrier (1) and the Papillon (1). Twenty dogs constituted the CLM group including CKCS (15), Chihuahuas (2), a Papillon (1), Staffordshire bull terrier (1) and a Pug (1). Ten dogs without evidence of CLM on MR imaging were classified as the control group including French bulldogs (5), Boxers (2), a Chihuahua (1), Pug (1) and a CKCS (1). ... Various measurements were derived from magnetic resonance images of the brain and craniocervical junction of thirty brachycephalic dogs in a flexed-neck position. Each dog was assigned a clinical grade. The distance from the planum of the foramen magnum to the pons was significantly reduced, providing evidence of craniocephalic disproportion similar to human patients with Chiari malformation type I. ... The reduction of the foramen magnum to pons distance in the current study could reflect regional shortening of the caudal fossa, or could reflect caudal displacement of the pons by, for example, an overcrowded forebrain. The correlation between this measurement and the degree of cerebellar herniation is interesting as it has not previously been identified and adds further value to this parameter and its association with CLM in dogs. ... Cerebral length relative to cranial length was significantly increased in dogs with CLM compared with control dogs, supporting the hypothesis that CLM is governed by a global overcrowding of the brain, dissimilar to the human condition. Significant correlations were identified between these measurements and the extent of cerebellar herniation. No significant differences or correlations were identified with clinical grade. This is the first described morphometric analysis to use a strictly brachycephalic study population inclusive of a control group free from CLM. ... Another study found that syringomyelia is significantly associated with a smaller frontal sinus size (Scrivani et al., 2007). The findings of the current study suggest that this implication could be extended to the brachycephalic subgroup, and that a simple, linear measurement could potentially be used to assess global crowding proven by volumetric studies, which required more specialized software. Overcrowding in the supratentorial portion of the cranium could potentially displace the entire cerebellum and brainstem caudally against the occipital bone contributing to the development of cerebellar herniation and resultant alterations in CSF. By this theory, forebrain overcrowding could be responsible for the caudal displacement of the pons, thereby explaining the reduction in distance between the pons and the foramen magnum as identified in this study. ... In this study, there was no significant difference in mid cerebellar surface area relative to mid total brain surface area between brachycephalic dogs with and without CLM.

Foramen Magnum Decompression with Duraplasty Using Lyoplant® for Caudal Occipital Malformation Syndrome in a Dog. Wan-Sang Park, SungHun Kang, Jun-Su Kim, Sung-Guon Park, Hee-Sup Moon, Sang-yeon Kim, Sung-Jin Hong, Tae-Sung Hwang, Hee-Chun Lee, Yong-Hyun Hwang, Hyun Park, Jae-Hoon Lee. J. Vet. Clinics. December 2017;34(6):449-453. Quote: A 3-year-old castrated male Maltese dog, weighing 4.8 kg was referred with hindlimb ataxia and right forelimb proprioceptive deficits were shown for 20 months. Chiari-like malformation and syringomyelia diagnosed through MRI at a local animal hospital and Knuckling of right forelimb and reluctance to walk were managed with steroid. The medical management was getting ineffective to manage for the symptoms one month before referred. Physical and neurological examinations, radiography, computed tomography, and magnetic resonance imaging were performed and diagnoses of caudal occipital malformation syndrome (COMS) and subsequent syringomyelia (SM) were made. Given that pharmacological treatment was previously ineffective, surgical intervention was recommended. Foramen magnum decompression with duraplasty using Lyoplant® was performed. Three days post-surgery, the dog showed improved gait and activity. After 2 months, the dog received no additional prescription medications. At the 12-month follow-up after surgery, the dog showed no clinical problems or recurrences, despite complete cessation of pharmacological treatment. In present report, we applied Lyoplant® as a dural graft has been carried out in a dog with COMS. Surgical decompression with Lyoplant® was an effective long-term (12-month) treatment for COMS without the need for any pharmacological treatment.

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2018

Assessing the relative importance of health and conformation traits in the cavalier king Charles spaniel. Katrien Wijnrocx, Liesbeth François, Peter Goos, Nadine Buys, Steven Janssens. Canine Genetics & Epidemiology. January 2018. DOI 10.1186/s40575-017-0056-2. Quote: Background: The selection of a future breeding dog is a complicated task, in which disease characteristics and different traits have to be combined and weighed against one another. Truncation selection, that is the exclusion of affected animals, may be very inefficient when selecting on a large number of traits, and may result in a reduction of the genetic diversity in a population or breed. Selection could be facilitated by the use of a selection index that combines multiple traits or breeding values into one score. This however requires a consideration of their relative value according to their economic weight, which is difficult to express in monetary units for health traits. The use of a choice experiment to derive non-market values might be a solution to this problem. This is a pilot study to assess the potential use of choice experiments to ascertain the public preference and relative importance attached to health- and conformation traits in the selection of a Cavalier King Charles spaniel. ... Our study also indicated that the “level of inbreeding” is considered important by breeders and owners. ... This study invited breeders and owners to express their attitudes towards the importance of traits in the selection of a CKCS by means of a choice experiment. ... The focus was on two prevalent disorders, mitral valve disease and syringomyelia, and on several important conformation traits such as muzzle length and eye shape. Based on available prior information, a Bayesian D-optimal design approach was used to develop a choice experiment and the resulting choice sets. Results: Every participant (breeder or owner) in the choice experiment was presented with a total of 17 choice sets, in which at most four traits could vary to reduce the cognitive burden. ... As the number of attributes in a choice experiment is limited to reduce the cognitive burden of the respondents, only following attributes were considered to be of major interest in the choice of a CKCS: shape of the eyes, coat colour, muzzle length, level of inbreeding, purchase price of the dog, syringomyelia status, eye disease status, and mitral valve disease status. ... A total of 114 respondents [Respondents were Belgian, Danish, UK and USA breeders and owners] participated in the choice experiment and results showed that respondents (breeders/owners) current attitudes were directed towards health (syringomyelia and mitral valve disease), followed by eye shape and level of inbreeding. ... The choice experiment showed that no difference in preference between breeders or owners, they both attached most importance to the health traits such as SM and MVD. ... Conclusions: This approach identifies the value breeders and owners attach to certain traits in the breeding objective. The resulting relative weights, represented as the logworths obtained from the choice experiment, could be an alternative to economic weights. They could be implemented as a weight when breeding values are available, but more study on this topic will be necessary. A challenge in this approach is to scale up the experiment with additional traits. Moreover, for other traits, the genetic parameters and correlations should be known first, in order to include them in the health selection index as well.

Computer simulation of syringomyelia in dogs. Srdjan Cirovic, Robert Lloyd, Jelena Jovanovik, Holger A. Volk, Clare Rusbridge. BMC Vet. Res. March 2018;14:82-91. Quote: Background: Syringomyelia is a pathological condition in which fluid-filled cavities (syringes) form and expand in the spinal cord. Syringomyelia is often linked with obstruction of the craniocervical junction and a Chiari malformation, which is similar in both humans and animals. Some brachy-cephalic toy breed dogs such as Cavalier King Charles Spaniels (CKCS) are particularly predisposed. The exact mechanism of the formation of syringomyelia is undetermined and consequently with the lack of clinical explanation, engineers and mathematicians have resorted to computer models to identify possible physical mechanisms that can lead to syringes. We developed a computer model of the spinal cavity of a CKCS suffering from a large syrinx. The model was excited at the cranial end to simulate the movement of the cerebrospinal fluid (CSF) and the spinal cord due to the shift of blood volume in the cranium related to the cardiac cycle. To simulate the normal condition, the movement was prescribed to the CSF. To simulate the pathological condition, the movement of CSF was blocked. Results: For normal conditions the pressure in the SAS was approximately 400 Pa and the same applied to all stress components in the spinal cord. The stress was uniformly distributed along the length of the spinal cord. When the blockage between the cranial and spinal CSF spaces forced the cord to move with the cardiac cycle, shear and axial normal stresses in the cord increased significantly. The sites where the elevated stress was most pronounced coincided with the axial locations where the syringes typically form, but they were at the perimeter rather than in the central portion of the cord. This elevated stress originated from the bending of the cord at the locations where its curvature was high. Conclusions: The results suggest that it is possible that repetitive stressing of the spinal cord caused by its exaggerated movement could be a cause for the formation of initial syringes. Further consideration of factors such as cord tethering and the difference in mechanical properties of white and grey matter is needed to fully explore this possibility. (See also this December 2015 abstract by the same research team.)

Evidence of negative affective state in Cavalier King Charles Spaniels with syringomyelia. Alastair Cockburn, Melissa Smith, Clare Rusbridge, Carol Fowler, Elizabeth S. Paul, Joanna C. Murrell, Emily J. Blackwell, Rachel A. Casey, Helen R. Whay, Michael Mendl. Applied Anim. Behaviour Sci. April 2018;201:77-84. Quote: Syringomyelia is a common and chronic neurological disorder affecting Cavalier King Charles Spaniels. The condition is putatively painful, but evaluating the affective component of chronic pain in non-human animals is challenging. Here we employed two methods designed to assess animal affect – the judgement bias and reward loss sensitivity tests – to investigate whether Cavalier King Charles Spaniels with syringomyelia (exhibiting a fluid filled cavity (syrinx) in the spinal cord of ≥2 mm diameter) were in a more negative affective state than those without the condition. Dogs with syringomyelia did not differ in age from those without the condition, but owners reported that they scratched more (P < 0.05), in line with previous findings. They also showed a more negative judgement of ambiguous locations in the judgement bias task (P < 0.05), indicating a more negative affective state, but did not show a greater sensitivity to loss of food rewards. These measures were unaffected by whether the dog was or was not receiving pain-relieving medication. Across all subjects, dogs whose owners reported high levels of scratching showed a positive judgement bias (P < 0.05), indicating that scratching was not directly associated with a negative affective state. Tests of spontaneous behaviour (latency to jump up to or down from a 30 cm high platform) and physiology (thermography of the eye) did not detect any differences. These results provide initial evidence from the judgement bias task that syringomyelia may be associated with negative affect in dogs, and open the way for further and larger studies to confirm findings and investigate the effects of medication in more detail. • Dogs with syringomyelia (SM) show a more negative judgement bias than those without SM. • SM dogs do not show a greater sensitivity to reward loss than SM-free dogs. • SM dogs scratch more than SM-free dogs but do not differ in jump up/down tests. • SM may be associated with negative affect in Cavalier King Charles Spaniels.

Understanding and Treating Chiari-like Malformation and Syringomyelia in Dogs. Ashley C. Hechler, Sarah A. Moore. Topics in Compan. Anim. Med. March 2018. doi:10.1053/j.tcam.2018.03.002 Quote: Chiari-like malformation (CM) and syringomyelia (SM) are common and debilitating conditions in toy and small breed dogs. CM, considered ubiquitous in the cavalier King Charles spaniel (CKCS) population, results in abnormal cerebrospinal fluid dynamics which can lead to the development of SM. The clinical signs associated with CM/SM are frequently confused with other otologic and dermatologic conditions, which may delay appropriate treatment. A definitive diagnosis of CM/SM requires advanced imaging; however, due to expense associated with this, many cases are managed presumptively and symptomatically for the condition. The primary goal of treatment is to manage neuropathic pain and neurologic deficits through pharmaceutical or surgical approaches. Current literature suggests that most CM/SM-affected dogs have progression of their clinical signs in spite of medical or surgical management; however, most maintain a good quality of life based on owner assessments. Lack of correlation between structural markers of disease and clinician and owner-derived measures of neuropathic pain highlight the need for more robust, quantitative measures of pain in this common veterinary disease. ... CM/SM is a complex condition of small and toy breed dogs for which both medical and surgical management can be considered. Development of objective, quantitative assessments to document both the presence and severity of neuropathic pain are important for future studies comparing outcomes between medical and surgical management, and for documenting response to novel medical therapies. Clinicians should be aware that the most common clinical sign of the condition is phantom scratching, which can be mistaken for dermatologic and otologic conditions also common in small breed dogs. The genesis of phantom scratching in CM/SM is unclear, and its relevance as a surrogate marker of neuropathic pain in veterinary clinical studies should be further scrutinized.

A genome-wide association study identifies candidate loci associated to syringomyelia secondary to Chiari-like malformation in Cavalier King Charles Spaniels. Frédéric Ancot, Philippe Lemay, Susan P. Knowler, Karen Kennedy, Sandra Griffiths, Giunio Bruto Cherubini, Jane Sykes, Paul J. J. Mandigers, Guy A. Rouleau, Clare Rusbridge, Zoha Kiba. BMC Genetics. March 2018;19:16. Quote: Background: Syringomyelia (SM) is a common condition affecting brachycephalic toy breed dogs and is characterized by the development of fluid-filled cavities within the spinal cord. It is often concurrent with a complex developmental malformation of the skull and craniocervical vertebrae called Chiari-like malformation (CM) characterized by a conformational change and overcrowding of the brain and cervical spinal cord particularly at the craniocervical junction. CM and SM have a polygenic mode of inheritance with variable penetrance. Results: We identified six cranial T1-weighted sagittal MRI measurements that were associated to maximum transverse diameter of the syrinx cavity. Increased syrinx transverse diameter has been correlated previously with increased likelihood of behavioral signs of pain. We next conducted a whole genome association study of these traits in 65 Cavalier King Charles Spaniel (CKCS) dogs (33 controls, 32 with extreme phenotypes). Two loci on CFA22 and CFA26 were found to be significantly associated to two traits associated with a reduced volume and altered orientation of the caudal cranial fossa. Their reconstructed haplotypes defined two associated regions that harbor only two genes: PCDH17 on CFA22 and ZWINT on CFA26. PCDH17 codes for a cell adhesion molecule expressed specifically in the brain and spinal cord. ZWINT plays a role in chromosome segregation and its expression is increased with the onset of neuropathic pain. Targeted genomic sequencing of these regions identified respectively 37 and 339 SNPs with significantly associated P values. Genotyping of tagSNPs selected from these 2 candidate loci in an extended cohort of 461 CKCS (187 unaffected, 274 SM affected) identified 2 SNPs on CFA22 that were significantly associated to SM strengthening the candidacy of this locus in SM development. Conclusions: We identified 2 loci on CFA22 and CFA26 that contained only 2 genes, PCDH17 and ZWINT, significantly associated to two traits associated with syrinx transverse diameter. The locus on CFA22 was significantly associated to SM secondary to CM in the CKCS dog breed strengthening its candidacy for this disease. This study will provide an entry point for identification of the genetic factors predisposing to this condition and its underlying pathogenic mechanisms.

2D quantification and characterisation of the spinal cord dorsal horn neuronal population in Cavalier King Charles Spaniels with syringomyelia. Zoë Nalborczyk, Javier Salguero, Fernando Constantino-Casas, Penny Watson, Clare Rusbridge. BSAVA Congress 2018 Proceedings. April 2018;p. 430. Quote: Objectives: Syringomyelia is characterised by fluid-filled lesions in the spinal cord. A classic sign of severe syringomyelia is ‘phantom scratching’, the pathogenesis of which is unclear. It has been associated with a large dorsolateral syrinx at the level of the C3 and C4 spinal segments with damage to the superficial dorsal horn. We compared populations of inhibitory and excitatory interneurons in the dorsal horn of the middle cervical spinal cord segments between ‘scratchers’ and ‘non-scratchers’ to further
investigate this. Methods: Using image analysis software and immunohistochemistry the constituents and neuronal populations of the middle cof the middle cervical spinal cord segmentservical spinal cord segments of the dorsal horn for four cohorts were identified and compared. These four cohorts included dogs with symptomatic syringomyelia and phantom scratching, dogs with symptomatic syringomyelia, dogs with asymptomatic syringomyelia and dogs with neither syringomyelia nor phantom scratching. Results: ‘Scratchers’ had significantly larger central cavities than ‘non-scratchers’. There were significant differences in the distribution of inhibitory interneurons in the left and right dorsal horn of the spinal cord between the four cohorts. There were no significant differences in excitatory interneuron distribution. Conclusions: The results suggest there are differences in the number of inhibitory interneurons in one or more laminae of the left and right dorsal horn between cohorts but does not identify in which lamina(e) the differences lie. Further complex statistical analysis and methodology alteration are required to grasp the true significance of these results in relation to the development of phantom scratching in dogs with severe syringomyelia.

Behavioural and clinical signs of Chiari-like malformation and syringomyelia in Cavalier King Charles Spaniels. Clare Rusbridge. BSAVA Congress 2018 Proceedings. April 2018;pp. 430-431. Quote: Objectives: Chiari-like malformation (CM) and syringomyelia (SM) are associated with behavioural signs of pain and scratching. However there is poor data on which of these non-specific signs are the most useful for indicating symptomatic disease and whether associated with CM or SM or both. Methods: The medical records of Cavalier King Charles Spaniels presenting with history of behavioural signs of pain and CM with or without SM were analysed. Dogs with other causes of pain or scratching were excluded. Maximum transverse diameter of the syrinx or central canal dilation (CCD) was measured and the dogs were divided into no SM (16 dogs); CCD<2 mm (12 dogs); SM 2–3.9 mm (23 dogs): SM≥4 mm (50 dogs). Results: The most common signs in all groups was vocalisation (spontaneous, changing head position, on rising, when lifting dog from under the sternum); scratching/rubbing the head/ears; unwilling or difficulty jumping/doing stairs; hyperaesthesia to palpation of the cervical, thoracic and/or lumbar spine; decreased exercise ability; lethargy and sleep disturbance. Phantom scratching, scoliosis, weakness and postural deficits were only seen in the SM≥4 mm group. Conclusion: This study has limitations due to its retrospective nature but provides data for planning future clinical trials. Results suggest CM with or without SM may present with behavioural signs of pain particularly associated with changes in head position. Dogs may scratch or rub their head/ears and examination may suggest spinal hyperaesthesia. SM specific signs tend to be associated with larger syringes and likely damage of the spinal cord. (See also this July 2019 article.)

Network analysis of multiple brain morphometric features in dogs to isolate key driving factors for syringomyelia. Olivia Saunders, Tobias Schwarz, Katia Marioni-Henry, Tom Freeman, Nina Marie Rzechorzek. BSAVA Congress 2018 Proceedings. April 2018;p. 494. Quote: Objectives: Syringomyelia (SM) is an extremely painful condition that commonly affects the Cavalier King Charles Spaniel (CKCS) and represents one of the most important welfare issues currently present in veterinary neurology. Much controversy exists surrounding the development of SM; historically, diagnosis has focused on Magnetic Resonance Imaging (MRI) features of the spinal cord and Chiari-like malformation (CLM) at the skull-neck junction, overlooking potentially relevant features of the brain. Three-dimensional estimation of brain ventricular system volume in brachycephalic dogsThis study set out to test whether any MRI-derived morphometric features of the brain may explain the predisposition of dogs to SM. Methods: An unbiased approach was taken using network analysis software (Miru) to evaluate enrichment within 8,432 data points, incorporating clinical data and blinded retrospective measurements of brain MRI features in 246 dogs, including 22 CKCSs. ... 22 measures of general brain and ventricular morphology, established measures of CLM, derived measures and normalization factors. ...  Results: Key preliminary findings included a significant correlation between brain ventricle morphometry and breed type in terms of length of the skull. CKCS dogs clustered independently based on median age at MRI, brain length-to-volume ratio, cerebellar volume and sulcus depth. To date, this study has generated the most comprehensive analysis of MRI-based brain morphometry in dogs, highlighting candidate measures to explore further as putative drivers of SM. Conclusions: Preliminary analysis has clustered brachycephalic breeds on the basis of ventricular morphology, and a proportion of CKCS dogs due to a combination of factors, including ventricular morphology. Further analysis of this data is ongoing and will focus on parameters that isolate CKCS dogs independently of features associated generally with brachycephaly and parameters that isolate dogs with SM irrespective of breed.

Three-dimensional estimation of brain ventricular system volume in brachycephalic dogs with and without Chiari-like malformation and syringomyelia. Clare Perrott, Augusto Coppi, E. Jovanovik, Clare Rusbridge. BSAVA Congress 2018 Proceedings. April 2018;p. 495. Quote: Objectives: To ascertain if dogs with Chiari-like malformation (CM) and syringomyelia (SM) are more likely to have dilation of the lateral, third and fourth ventricles and whether these measurements could enhance CMSM screening. Methods: Case control study that obtained quantitative volume measurements of lateral, third (including cavum velum interpositum and quadrigeminal cistern) and fourth (including mesencephalic aqueduct) ventricles using Cavalieri’s principle of stereology from T2-weighted sagittal brain magnetic resonance imaging (MRI). [Fig. 1] Three-dimensional estimation of brain ventricular system volume in brachycephalic dogs The sample was composed of a Chihuahua group; five with CMSM and five normal and a mixed brachycephalic toy breed group; eight with CMSM and eight normal breed matched. Cavalier King Charles Spaniels (CKCS) were not included in the cohort. Data analysis included descriptive statistics. Two-sample T-Tests and Mood Median Tests. Results: Stereology measurements showed no significant difference in the lateral, third or fourth ventricle volume between Chihuahuas and mixed brachycephalic breeds with and without CMSM. Conclusions: A novel stereology based methodology has successfully quantified ventricular volumes and may be applicable for future studies in diseases that affect brain and ventricular volume. Currently a recommendation cannot be made that the Kennel Club British Veterinary Association CMSM Health Scheme should include assessment of ventricular size. Continued research with increased sample sizes to reduce biological variability and inclusion of CKCS would further confirm whether assessment of ventricular size could provide added benefit. Additional screening methods for CMSM are required to improve the health and welfare of predisposed breeds.

Investigation of Sensory Thresholds in Cavalier King Charles Spaniels with and without Chiari-like Malformations and Syringomyelia. C. R. Sparks, A. Gorney, K. Williams, B. D. X. Lascelles, N. J. Olby. Vet. Comp. Orthop. Traumatol. May 2018;31(S 01):A6 (A0016). Quote: Introduction: Ninety-two percent of Cavalier King Charles Spaniels (CKCS) have a skull malformation called Chiari-like malformation (CM). CM is frequently associated with syringomyelia (SM), an accumulation of fluid within the spinal cord that has been linked to a neuropathic pain syndrome. The purpose of this study was to obtain quantitative data on thermal and mechanical thresholds in CKCS with and without SM. We hypothesized that CKCS affected with SM will have lower sensory thresholds when compared with unaffected dogs. Materials and Methods: Fifty-four dogs were classified as symptomatic or not by their owners, presence of pain was noted on neurological examination, sensory thresholds testing was performed, and SM was identified on magnetic resonance imaging. Results: Owners reported 24/54 dogs as painful, 33/54 had scratching signs, 40/54 were painful on examination and 34/54 had SM. There was no significant difference in sensory thresholds between dogs with and without SM (p > 0.5). Owner-reported symptomatic dogs had lower mechanical thresholds on the paw (median: 0.367 kg) and neck (2.075 kg) compared with asymptomatic dogs (0.6275 kg and 2.545 kg, respectively) (p = 0.009 and 0.007, respectively). Dogs that exhibited pain on neurological examination had decreased latencies to heat at the thorax (median = 17.55 seconds) compared with dogs that were not painful (22.16 seconds) (p = 0.03). Mechanical thresholds were lower on the side of the neck that corresponded to lateralization of SM in dogs with asymmetrical syrinxes (p = 0.015, 0.09). Discussion: This information can be leveraged to optimize treatment protocols and objectively study efficacy of future therapeutics in CKCS.

Mechanical Quantitative Sensory Testing in A Canine Translational Model of Neuropathic Pain: A Pilot Investigation. S. A. Moore, E. T. Hostnik, L. Cole. Vet. Comp. Orthop. Traumatol. May 2018;31(S 01):A4 (A0011). Quote: Introduction: Drug development related to neuropathic pain is inefficient, related at least in part to limited predictive value of experimental models. The utility of pet dogs with spontaneous disease for use as clinical translational models has recently become a focus. Syringohydromyelia (SM) is a painful spontaneous neurological disorder common in pet dogs of the Cavalier King Charles Spaniel (CKCS) breed which results in behaviours that have long been suggested by veterinarians to represent a neuropathic pain phenotype. Materials and Methods: Mechanical quantitative sensory testing was performed using an electronic von Frey anesthesiometer in normal CKCS (n=9) and CKCS with syringomyelia (SM) (n=7). We hypothesized that dogs with SM would have significantly lower mechanical sensory threshold (ST) than dogs without SM, consistent with hyperesthesia and a neuropathic pain phenotype. Results: Mean sensory threshold (ST) for normal CKCS was 220.4 ± 42.5 g for the thoracic limbs and 175.6 ± 21.5 g for the pelvic limbs. Mean ST for SM-affected CKCS was 148.8 ± 21.1 g for the thoracic limbs and 129.2 ± 8.2 g for the pelvic limbs. There was a statistically significant decrease in ST in the pelvic limbs of SM-affected CKCS compared with normal (p = 0.045). This relationship was also present in the thoracic limbs but did not achieve statistical significance (p = 0.094). Discussion: Spontaneously occurring SM in pet CKCS may represent a valuable clinical animal model through which to study interventions aimed at improving treatment of neuropathic pain.

Retrospective study of 16 Cavalier King Charles Spaniel dogs diagnosed with Chiari-Like Malformation and Syringomyelia. Magnetic Resonance Imaging and Surgical Management. Catalina Cucos, Ates Barut, Iuliana Ionaşcu, Radu Constantinescu, Constantin Vlagioiu. Bulletin of Univ. of Ag. Scie. & Vet. Medi. Cluj-Napoca. May 2018;75(1):118-122. Quote: Chiari-like malformation (CM) and Syringomyelia (SM) are complex neurological disorders, that affects the brain and respectively the spinal cord. These conditions affect certain toy breed dogs, among which the Cavalier King Charles Spaniel breed is overrepresented, causing numerous clinical signs, of which the neurological pain is commonly observed.The purpose of this research was to describe the CM/SM magnetic resonance images, to discuss the medical management and to track the outcome of the patients. All of the 16 Cavalier King Charles Spaniel dogs underwent surgical treatment, consisting of cranio-cervical decompression, combined with drug therapy. Thirteen of the 16 cases presented good results with clinical improvement of the symptomatology, escpecially decreasing the neuropathic pain, and increasing the quality of life. The other 3 cases presented no improvement of the symptomatology. ... The study was performed on 16 Cavalier King Charles dogs, with a median age of 35 months, 10 females and 6 males. The youngest patient in the group was 14 months old and the oldest was 97 months old. ... In all of the dogs included in this study MRI sequences of the brain, cervical and thoracic spinal segments were performed, showing mild identation of the cerebellum in 3 cases, marked identation of the cerebellum in 9 cases, and herniation of the cerebellum through foramen magnum in 4 cases. All the cases presented cervical fluid-filled cavities within the spinal cord at the time of examination, the width syrinx varied between 1.13 mm and 6.73 mm. ... All the dogs made a quick recovery after surgery, the neuropathic pain, spontaneous vocalization and scratching improved in all dogs after the surgery. In the postopertively period, none of the dogs showed complete resolution of the clinical signs.

Morphometric Analysis of Spinal Cord Termination in Cavalier King Charles spaniels. Courtney Sparks. ACVIM Forum, Abstract N-15. June 2018. Quote: Cavalier King Charles spaniels (CKCS) suffer from Chiari-like malformation (CM), a skull malformation that causes crowding of the caudal fossa, and syringomyelia (SM). Affected dogs show signs of pain and frequently show lumbosacral pain. Tethered cauda equina has been reported in people with CM but currently there is no morphometric data on the caudal aspect of the vertebral column and spinal cord in CKCS. The purpose of this study was to compare the location of the conus medullaris in CKCS with other size-matched breeds. We hypothesized that the spinal cord terminates more caudally in CKCS. A retrospective study was conducted on 90 dogs with thoracolumbar magnetic resonance imaging (MRI). Dog breeds were grouped as CKCS (n=48), and brachycephalic (n=21) and non-brachycephalic (n=20) size-matched controls. MRI identifiers were removed to blind the observer. Termination of the spinal cord was determined from T2-weighted sagittal and axial images as the 6th (L6), or 7th lumbar vertebra (L7), or sacrum. Breed was revealed after Chi-squared analyses were performed. Among 48 CKCS, the spinal cord terminated at L6 in 3, L7 in 23, and sacrum in 22 dogs compared with 8 at L6, 27 at L7 and 5 at sacrum in 41 controls. Spinal cord termination was significantly more caudal in CKCS as compared to brachycephalic (P = 0.015) and non-brachycephalic breeds (P = 0.005). There was no difference between size-matched controls (P = 0.157). There is a need to investigate whether tethering of the cauda equina contributes to signs of pain in CKCS. (See also this January 2021 article.)

Prevalence of syringomyelia in clinically unaffected Cavalier King Charles Spaniels in Germany (2006–2016). Sabine Schulze, Miriam Refai, Martin Deutschland, Klaus Failing, Martin Schmidt. Tierarztliche Praxis. June 2018;46(03):157-162. Quote: Objective: The aim of the study was to investigate the prevalence of syringomyelia in clinically unaffected Cavalier King Charles Spaniels (CKCS) in Germany. Material and methods: From 2006 to 2016 a total of 339 asymptomatic CKCSs from all over Germany were included. Age ranged from 3 months to 11 years (mean 3.72 years ± 2.17 years). T1- and T2-weighted magnetic resonance images of the head and cervical spine were obtained. Results: Overall, 163 out of 339 (48.1 %) CKCSs showed evidence of syringomyelia. The results (odds ratio of 1.27 per year; p < 0.0001) corroborate the findings of other studies, in which the risk of developing syringomyelia increases with age. Conclusion and clinical relevance: In conclusion, around half of the dogs within the German CKCS population are affected by syringomyelia. The prevalence of syringomyelia of the German CKCS population is similar to that of the British CKCS population, which is subjected to breeding strategies on the basis of magnetic resonance imaging investigations.

Morphometric analysis of brachycephalic features identified by machine learning technique in dogs with/without syringomyelia. S.P. Knowler, M. Spiteri, A.K. McFadyen, F. Stringer, K. Wells, C. Rusbridge. ACVIM Forum Abstract N-14. June 2018. Quote: The aim of the study was a follow up morphometric analysis of features associated with Cavalier King Charles spaniel (CKCS) with syringomyelia (SM) secondary to Chairi-like malformation (CM) that had first been identified by an innovative machine learning technique which removes human bias. Recent studies have suggested that CM is a more complex disorder than originally thought and affected by features associated with brachycephaly such as olfactory bulb rotation and rostral flattening of the forebrain. T2W sagittal DICOM anonymized images of 66 CKCS, over 4 years of age were obtained, comprising i) 26 dogs without SM with no or <2mm wide central canal dilation (ccd) ii) 40 dogs with SM with syrinx width 4mm or over. Morphometric analysis of the shape and position of the soft palate relative to the skull base and the nature of rostral skull flattening was obtained. In SM dogs, the distance between the rostral end of the palate and i) sella turcica (P= 0.049) ii) foramen magnum basioccipital (P=0.030) were significantly reduced, as was the maximum distance through the palate centroid (P=0.015). However, the reduced distance between the brain and frontal bone was highly significant (P <0.001). The reduction in distance between the olfactory bulb and the sella turcica may be of interest (P = 0.054). Discriminate analysis/logistic regression revealed that rostral skull flattening dominated any model but when removed, ratio of maximum distance through the palate centroid to cerebral height to cerebrum height was highly significant (P< 0.001). Conclusion: The characteristics of CKCS with SM include osseous insufficiency in the skull and changes in the shape of the soft palate which were implicated by machine learning technology.

Morphogenesis of canine Chiari malformation and secondary syringomyelia: Disorders of cerebrospinal fluid circulation. Susan P. Knowler, Gabriel L. Galea, Clare Rusbridge. Front. Vet. Sci. July 2018;doi: 10.3389/fvets.2018.00171 Quote: Chiari-like Malformation (CM) and secondary syringomyelia (SM), as well as their analogous human conditions, is a complex developmental condition associated with pain and accompanying welfare concerns. CM/SM is diagnosed ever more frequently, thanks in part to the increased availability of magnetic resonance imaging in veterinary medicine. Research over the last two decades has focused primarily on its pathophysiology relating to overcrowding of the cranial caudal fossa. More recent characterisations of CM/SM include brachycephaly with osseous reduction and neural parenchymal displacement involving the entire brain and craniocervical junction to include rostral flattening, olfactory bulb rotation, increased height of the cranium, reduced cranial base with spheno-occipital synchondrosis angulation, reduced supraoccipital and interparietal crest and rostral displacement of the axis and atlas with increased odontoid angulation. The most shared manifestation of CM is the development of fluid-filled pockets (syrinx, syringes) in the spinal cord that can be readily quantified. Dogs with symptomatic CM without SM have a reduced basioccipital bone, compensatory increased cranial fossa height with displaced parenchyma whereby the cerebellum is invaginated beneath the occipital lobes but without compromising cerebrospinal fluid channels enough to cause SM. Thus, broadly defined, CM might be described as any distortion of the skull and craniocervical junction which compromises the neural parenchyma and cerebrospinal fluid circulation causing pain and/or SM. The aetiology of CM is multifactorial, potentially including genetically-influenced, breed-specific abnormalities in both skeletal and neural components. Since causation between specific morphologic changes and SM or clinical signs is unproven, CM might be more appropriately considered as a brachycephalic obstructive CSF channel syndrome (BOCCS) rather than a single malformation. Understanding the normal development of the brain, skull and craniocervical junction is fundamental to identifying deviations which predispose to CM/SM. Here we review its anatomical, embryological, bio-mechanical, and genetic underpinnings to update the profession’s understanding of this condition and meaningfully inform future research to diminish its welfare impact.

Retrospective Study of 37 Cavalier King Charles Spaniel Dogs Diagnosed with Chiari-Like Malformation and Syringomyelia. table Cătălina Anca Cucoș, Radu Constantinescu, Ateș Barut, Iuliana Ionașcu, Constantin Vlăgioiu. Table 3EuroBiotech J. July 2018;2(3):161-164. Quote: Chiari-like malformation represents a congenital anomaly that affects the bony cranial base and the hindbrain, leading to fluid filled cavities formation in the spinal cord, condition named Syringomyelia. This paper aims to assess the variety of the clinical signs and to evaluate the magnetic resonance imaging findings in thirty- seven Cavalier King Charles Spaniel dogs. The study was performed over a four-year period, from 2013 to 2017, all cases underwent neurological examination, full diagnostic work-up, including magnetic resonance imaging scans of the brain, cervical and upper thoracic spinal cord. Thirty-seven dogs were included in this study, 23 females and 14 males, with a mean age of 3.6±2.1years. The commonest clinical findings encountered were neuropathic pain and vocalization, seen in all 37 cases, followed by scratching, facial rubbing, paw licking, air licking, tail chasing, seizures and unilateral facial paralysis. Different grades of cerebellar herniation and cervical syrinxes were noted in all cases, other magnetic resonance imaging findings encountered were medullary kinking, presyrinx and ventriculomegaly. In establishing the diagnosis of the Chiari-like malformation and Syringomyelia, the breed, clinical history and the symptomatology are very important, but only magnetic resonance imaging technique can provide quantitative assessment of the nervous system lesions. (See also this August 2018 abstract.)

Clinical and diagnostic imaging features of Chiari-like malformation and Syringomyelia in Cavalier King Charles Spaniel dogs – retrospective study. Catalina Anca Cucos, Radu Constantinescu, Ates Barut, Iuliana Ionascu, Constantin Vlagioiu. J. Biotechnology. August 2018;280(Supp):s75-s76. Quote: Chiari-like malformation and Syringomyelia are complex neurological disorders that affects the hindbrain, the bony cranial base and spinal cord. The purpose of this study is to evaluate the variety of the clinical signs and to discuss the magnetic resonance imaging findings in Cavalier King Charles Spaniel dogs. Thirty-seven dogs with a mean age of 3.6±2.1 years were included in this study, 23 females and 14 males. Only dogs that underwent neurological examination, full diagnostic work-up, including magnetic resonance imaging scans of the brain, cervical and upper thoracic spinal cord were considered. Neuropathic pain and vocalization were the commonest clinical findings, encountered in all cases, followed by scratching (82%), facial rubbing (29.7%),pawlicking (10.6%), air licking (10.6%), tail chasing (6.4%), seizures (2.7%) and unilateral facial paralysis (2.7%). The magnetic resonance imaging data revealed different grades of cerebellar herniation and cervical syrinxes in all cases, medullary kinking (89.2%), presyrinx – spinal cord edema (51.3%), ventriculomegaly (22.6%). In order to set Chiari-like malformation and Syringomyelia diagnosis, the breed, clinical history and symptomatology are very important, but magnetic resonance imaging has a fundamental role in establishing the diagnosis. (See also this July 2018 article.)

The Effect of Electromagnetic Fields on Post-Operative Pain and Locomotor Recovery in Dogs with Acute, Severe Thoracolumbar Intervertebral Disc Extrusion: A Randomized Placebo-Controlled, Prospective Clinical Trial. Natalia Zidan, Joe Fenn, Emily Griffith, Peter J. Early, Chris L. Mariani, Karen R. Muñana, Julien Guevar, Natasha J. Olby. J. Neurotrauma. August 2018;35:1726-1736. Quote: Spinal cord injury (SCI) attributed to acute intervertebral disc extrusions (IVDEs) is common in dogs and is treated by surgical decompression. Dogs with sensorimotor complete injuries have an incomplete recovery. Pulsed electromagnetic fields (PEMFs) reduce post-operative pain through anti-inflammatory effects and there is growing evidence for neuroprotective effects. This randomized, controlled clinical trial evaluated the effect of PEMF on post-operative pain and neurological recovery in dogs with surgically treated sensorimotor complete SCI attributed to acute IVDE. Sixteen dogs with surgically treated complete thoracolumbar SCI were randomized to receive PEMF (15 min every 2 h for 2 weeks then twice-daily for 4 weeks) or placebo starting immediately after diagnosis. The primary outcome was gait score at 2 weeks. Secondary measures of gait, pain perception, and proprioceptive function were evaluated at 2 and 6 weeks. Plasma glial fibrillary acidic protein (GFAP) concentration was measured as an SCI biomarker. Post-operative pain was quantified by measuring mechanical sensory thresholds (MSTs) at control and surgical sites. There was no significant difference in demographics or GFAP concentration between the two groups at trial entry. There was no difference in primary outcome or in secondary measures of gait, but proprioceptive placing was significantly better at 6 weeks and GFAP concentrations were significantly lower at 2 weeks in the PEMF group. MSTs were significantly higher in the PEMF-treated group. We conclude that PEMF reduced incision-associated pain in dogs post-surgery for IVDE and may reduce extent of SCI and enhance proprioceptive placing. Larger clinical trials are warranted.

Osteopetrosis associated with chiari-like malformation in a cavalier king charles spaniel - radiological findings. Ricardo Fernandes, Chris Jordan, Joana Tabanez, Jeremy Rose, Clare Rusbridge, Colin Driver. 31st ESVN-ECVN Symposium. September 2018. Poster Abstract P51. Quote: Osteopetrosis is a genetically determined bone disease that develops as a result of malfunction of osteoclastic activity leading to excessive deposition of immature bone, thickening of cortical bone and narrowing of the medullary cavities. An 18 month-old male Cavalier King Charles Spaniel presented for evaluation of cervical hyperesthesia. Brain and spinal MRI revealed a thickening and sclerosis (markedly hypointense signal on T1 sequences) of the calvaria with complete absence of bone marrow in the bones of the skull and vertebral bodies. There was severe Chiari-like malformation with herniation of the cerebellum and medulla into the foramen magnum. The occipital bone was markedly dysplastic and was compressing the caudal aspect of the cerebellum. The medulla was compressed by the cerebellum dorsally and by the dens of the axis ventrally. Spinal MRI revealed syringomyelia within the C2-C3 and C5-L3 segments. The maximal width of a syrinx (4.8mm) occurred at the level of T4, at which level very little spinal cord parenchyma remained. Radiography confirmed thickening of the cortices and narrowing of the medullary cavities of the appendicular skeleton. Haematology confirmed a non-regenerative anaemia consistent with myelopthisis. We hypothesise that a mass effect from the calvarial thickening leads to reduced volume of the caudal fossa and cerebellar herniation. The absence of osteoclastic activity may lead to abnormal growth of the occipital bone resulting in a smaller caudal fossa. This is the first case report where MR findings in a patient with osteopetrosis associated with Chiari-like malformation are described in veterinary medicine. (See also this March 2019 article on the same study.)

Investigation of sensory thresholds in Cavalier King Charles Spaniels with and without Chiari-like malformations and syringomyelia. Figure 1Courtney R. Sparks, Angela Gorney, Kim Williams, Emily H. Griffith, Sofia Cerda-Gonzalez, B. Duncan X. Lascelles, Natasha J. Olby. J. Vet. Int. Med. October 2018. DOI: 10.1111/jvim.15297 Quote: Background: Cavalier King Charles Spaniels (CKCS) suffer pain associated with Chiari-like malformation and syringomyelia (CMSM). People suffer from a similar condition and describe numerous sensory abnormalities. Sensory changes have not been quantified in affected CKCS. Objectives: To use quantitative sensory testing (QST) to quantify thermal and mechanical thresholds in CKCS and to compare QST in dogs with and without syringomyelia (SM). Animals: Forty-four CKCS. Methods: Prospective study. Dogs underwent neurological examinations and craniocervical magnetic resonance imaging (MRI). Thermal testing was performed over the humerus and thorax (n=32); mechanical testing was performed on the paw and neck (n=44). Latencies, thresholds, and response rates were compared with presence and severity of SM on MRI, presence of pain reported by the owner and pain identified on examination. Results: Thirty dogs had SM, 30 were painful on examination, 29 were owner-reported symptomatic. Thermal and mechanical variables were not significantly different based on presence or severity of SM. Dogs with pain on examination had decreased mechanical thresholds on the paw (0.38 kg, SD=0.18) and neck (2.05 kg, SD=0.74) compared to thresholds of dogs without pain on examination on the paw (0.60 kg, SD=0.30) and neck (2.72 kg, SD=0.57; P=.021). Conclusions and Clinical Importance: Mechanical and thermal sensitivity does not appear to be related to the presence of SM, but mechanical sensitivity appears to be related to the presence of pain and clinical signs. Mechanical testing may be useful for assessing sensory abnormalities during clinical trials. ... In summary, the purpose of our study was to quantify sensory thresholds in a cohort of CKCS with and without SM. We found no correlation between sensory thresholds (quantified by mechanical thresholds, thermal latencies and mechanical and thermal response rates) and SM. However, the presence or absence of pain on neurological examination did correlate with mechanical thresholds. These tools may be useful for assessing sensory changes in a clinical trial setting. Because of the inconsistencies between the presence and severity of SM and QST data, the relationship between SM and clinical signs deserves further examination.

Clinical Application of Diagnostic Imaging of Chiari-Like Malformation and Syringomyelia. Clare Rusbridge, Felicity Stringer, Susan P. Knowler. Frontiers in Vet. Sci. November 2018;doi: 10.3389/fvets.2018.00280. Quote: Chiari-like malformation (CM) and syringomyelia (SM) is a frequent diagnosis in predisposed brachycephalic toy breeds since increased availability of MRI. However, the relevance of that MRI diagnosis has been questioned as CM, defined as identification of a cerebellar herniation, is ubiquitous in some breeds and SM can be asymptomatic. ... The diagnosis of symptomatic CM and SM can be challenging in some breeds such as the Cavalier King Charles spaniel (CKCS) because CM, as defined by the BVA/KC Health Scheme is ubiquitous, and SM is prevalent but may be asymptomatic. ... This article reviews the current knowledge of neuroanatomical changes in symptomatic CM and SM and diagnostic imaging modalities used for the clinical diagnosis of CM-pain or myelopathy related to SM. Although often compared to Chiari type I malformation in humans, canine CM-pain and SM is more comparable to complex craniosynostosis syndromes (i.e., premature fusion of multiple skull sutures) characterized by a short skull (cranial) base, rostrotentorial crowding with rostral forebrain flattening, small, and ventrally orientated olfactory bulbs, displacement of the neural tissue to give increased height of the cranium and further reduction of the functional caudotentorial space with hindbrain herniation. MRI may further reveal changes suggesting raised intracranial pressure such as loss of sulci definition in conjunction with ventriculomegaly. In addition to these brachycephalic changes, dogs with SM are more likely to have craniocervical junction abnormalities including rostral displacement of the axis and atlas with increased odontoid angulation causing craniospinal junction deformation and medulla oblongata elevation. Symptomatic SM is diagnosed on the basis of signs of myelopathy and presence of a large syrinx that is consistent with the neuro-localization. The imaging protocol should establish the longitudinal and transverse extent of the spinal cord involvement by the syrinx. Phantom scratching and cervicotorticollis are associated with large mid-cervical syringes that extend to the superficial dorsal horn. If the cause of CSF channel disruption and syringomyelia is not revealed by anatomical MRI then other imaging modalities may be appropriate with radiography or CT for any associated vertebral abnormalities.

Craniovertebral Junction Anomalies in Small Breed Dogs with Atlantoaxial Instability: A Multicentre Case–Control Study. Maja A. Waschk, Beatriz Vidondo, Inés Carrera, Angel M. Hernandez-Guerra, Pierre Moissonnier, Ioannis N. Plessas, Martin J. Schmidt, Dietmar Schnötzinger, Franck Forterre, Christina Precht. Vet. Comp. Orthop. Traumatol. November 2018. DOI: 10.1055/s-0038-1675797. Quote: Objective: The main purpose of this study was to define criteria to systemically describe craniovertebral junction (CVJ) anomalies and to report the prevalence of CVJ anomalies in small breed dogs with and without atlantoaxial instability (AAI). Methods: Retrospective multicentre matched case–control study evaluating magnetic resonance imaging and computed tomographic images of small breed dogs with and without AAI for the presence of CVJ anomalies. Results: One hundred and twenty-two dogs were enrolled (61 with [including 3 cavalier King Charles spaniels] and 61 without AAI). Only dogs with AAI had dens axis anomalies such as separation (n = 20) or a short-rounded conformation (n = 35). Patients with AAI were more likely to have atlantooccipital overlapping based on transection of McRae's line by the dorsal arch of the atlas (odds ratio [OR] = 5.62, p < 0.01), a transection of Wackenheim's clivus line (OR = 41.62, p < 0.01) and rostral indentation of the occipital bone (OR = 2.79, p < 0.05). Patients with AAI were less likely to have a larger clivus canal angle (OR = 0.94, p < 0.01) and larger occipital bone lengths (OR = 0.89, p < 0.05). Clinical Significance: Small breed dogs with AAI are more likely to have other CVJ anomalies such as atlantooccipital overlapping or dens anomalies. The grade of brachycephaly does not differ between patients with and without AAI. Certain objective criteria from human literature were found useful for the assessment of both AAI and atlantooccipital overlapping such as McRae's line, Wackenheim's clivus line, and clivus canal angle. The classification criteria used can help to evaluate CVJ anomalies in a more systematic way.

Computed tomographic finding in Chiari like malformation in Cavalier King Charles Spaniel - case report. Purdoiu, R. C., Ondreka, N., Kiss, T., Popovici, C., Papuc, I., Danciu, C. G., Lazar, A. C., Lacatus, R. Universitatea de Stiinte Agricole a Banatului Timisoara, Medicina Veterinara. December 2018;51(2):106-111. Quote: The patient was a female Cavalier King Charles Spaniel, 21-month-old, that was initially diagnosed with otitis media, the symptoms debuted 10 months prior the CT scanning. The symptoms consist in discomfort at the level of the right ear, sratching and pain, the symptoms are not permanent, also the patient avoids long walking. Behavioral changes and the symptoms are more evident when the air pressure changes. A treatment for otitis media was administered, but the symptoms persists. Prednisone, antibiotics, antimitotic and clotrimazol drops was the therapy of choice. Otoscope examination show a narrowed additive canal. ... The CT [computed tomography] shows a typical brachycephalic head conformation with shortened facial bones and dome shaped calvarium. The supraoccipital bone is short and stunted, the foramen magnum appears enlarged. Part of the cerebellar vermis appears to protrude caudally beyond the bony margin of the supraoccipital bone. Marked but incidental deviation of the nasal septum is noted. ... A linear hypoattenuating area is seen centrally within the cervical spinal cord level with C2 and compatible with syringomyelia. Mild asymmetric dilation of the lateral ventricles of the brain is noted accentuating the right side. ... Changes of the occipital bone produce also occipital hypoplasia with incomplete formation of the bone (Fig. 6). ... In absence of MRI examination, the CT examination represent an alternative in diagnosing this pathology.

Figure 6 -- Occipital Hypoplasia

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2019

Pilot study of head conformation changes over time in the Cavalier King Charles spaniel breed. Susan Penelope Knowler, Lena Gillstedt, Thomas J Mitchell, Jelena Jovanovik, Holger Andreas Volk, Clare Rusbridge. Vet. Rec. January 2019;doi: 10.1136/vr.105135. Quote: Modern interpretation of head conformation in the Cavalier King Charles spaniel (CKCS) has favoured a smaller, more exaggerated, brachycephalic type than originally described in the 1929 breed standard. Recent research studies identified brachycephaly and reduced hind cranium as two conformational (dysmorphic) features that increase risk for symptomatic Chiari-like malformation and secondary syringomyelia (SM). A prospective pilot study investigated the hypothesis that dysmorphic head features could be assessed visually and correlated with risk of SM. ... This study aimed to find out if it is possible to identify risk of CM/SM in a dog’s head shape through evaluation with the eye alone by breed experts. ... Hypothesis: Head conformation (dysmorphic features) is correlated with risk of SM and can be evaluated with the eye alone by breed experts. ...  Thirteen CKCS, selected from anonymised photographic evidence, were physically appraised by authorised Kennel Club judges using a head shape checklist. These subjective evaluations were then matched with objective measurements of the cranium (cephalic index and rostrocaudal doming) and their subsequent MRI. A positive correlation (P=0.039) between the judges’ checklist score and rostrocaudal doming (hindskull ratio) and a positive correlation between the cephalic index and hindskull ratio (P=0.042) were identified. Five CKCS had no SM and their status tallied with 62 per cent of the judges’ evaluation. Although the ability of adjudicators to identify differences in head conformation varied, there was sufficient association between the dysmorphic parameters and the risk of SM to cause concern and propose a larger study in CKCS breed. ... This prospective investigation demonstrated that it was possible to compare subjective evaluation of head conformation with objective measurements and revealed a significant correlation between the subjective visual evaluation of head conformation and an objective evaluation of dorsoventral doming using photographs. However, this pilot investigation demonstrated that individual adjudicators can vary in their interpretation of the CKCS breed type and also suggests that measuring the cephalic index or rostrocaudal doming alone is not a reliable indicator of brachycephaly but should be taken together with a visual evaluation and take account of other features, such as those on the checklist and the size of the dog.

Figure 5

Mechanical sensory threshold in Cavalier King Charles spaniels with syringomyelia-associated scratching and control dogs. M.S.Thoefner, U.Westrup, N.Toft, O.J.Bjerrum, M.Berendt. Vet. J. February 2019; doi: 10.1016/j.tvjl.2019.01.011 Quote: Highlights: • Cavalier King Charles spaniels with syringomyelia are assumed to experience central neuropathic pain. • In humans with central neuropathic pain, monofilaments were used to evaluate somatosensory function. • The cervical mechanical sensory threshold was quantified with monofilaments in case and control dogs. • Mean mechanical sensory threshold was not significantly different between case and control dogs. • The complete somatosensory profile needs to be characterised in order to assess whether syringomyelia alters sensory thresholds. It is assumed that Cavalier King Charles spaniels with Chiari-like malformation and syringomyelia experience central neuropathic pain. An association between spinal cord parenchymal lesions and specific clinical signs (e.g. spontaneous and evoked scratching, withdrawal, and paroxysmal pain manifestations with vocalisation) has been suggested. This led to the hypothesis that mechanical sensory threshold is altered in clinical cases. The aim of this study was to quantify the cervical mechanical sensory threshold using Semmes-Weinstein monofilaments in nine Cavalier King Charles spaniels with Chiari-like malformation and assumed syringomyelia-associated central neuropathic pain compared to eight control dogs. Clinical and neurological examination including magnetic resonance imaging was undertaken. Mean mechanical sensory threshold was not significantly different between case and control dogs (t-test on log10 transformed data; P = 0.25). Substantial variation within and between dogs was seen, with individual thresholds ranging from 0.04 to 26 g in case dogs and from 0.02 to 10 g in control dogs. Based on these results, it is unlikely that Cavalier King Charles spaniels with Chiari-like malformation and syringomyelia have increased mechanical sensation characterised by lower mechanical sensory threshold when quantified with Semmes-Weinstein monofilaments. Whether clinical cases experience central neuropathic pain remains unknown. The assessment of sensory function in dogs with assumed central neuropathic pain should be multimodal and include not only mechanical but also tactile and thermal threshold quantification. The use of threshold quantification in a clinical setting is challenging due to an insufficient signal relative to the biological background noise within and between dogs.

Morphometric analysis of spinal cord termination in Cavalier King Charles Spaniels. Courtney R. Sparks, Ian Robertson, Natasha J. Olby. J. Vet. Intern. Med. February 2019; DOI: 10.1111/jvim.15437. Quote: Background: There is an association between Chiari malformations, syringomyelia (CMSM) and tethered cord syndrome (TCS) in people, suggesting Cavalier King Charles Spaniels (CKCS) with CMSM could also have TCS. Currently there are no data on the position of the caudal spinal cord structures in CKCS. Objective: To describe and compare location of spinal cord termination in CKCS with weightmatched controls and to examine the relationship between SM and spinal cord termination. Animals: Thirty-nine CKCS and 33 controls with thoracolumbar [TL] MRIs; 34 of 39 CKCS also had cervical MRIs. Methods: Blinded retrospective study. Spinal cord and dural sac termination were determined from T2-weighted sagittal and transverse images and half-Fourier acquisition single-shot turbo spin echo sequences. Intra-observer reliability was determined using kappa analysis. Presence of SM was compared with location of spinal cord and dural sac termination. Results: Intra-observer reliability was moderate for identifying spinal cord termination (Kappa = 0.6) and good for dural sac termination (Kappa = 0.8). The spinal cord terminated at lumbar vertebra 6 (L6) in 1, 7 (L7) in 22, and sacrum in 16 CKCS versus 9 at L6, 23 at L7, 1 at sacrum in controls. Spinal cord (P < .001) and dural sac (P = .002) termination were significantly more caudal in CKCS compared to controls. The presence of thoracolumbar SM was associated with more caudal dural sac termination in CKCS (P = .03). Conclusions and Clinical Importance: ... To conclude, we found that CKCS have a caudally displaced spinal cord and dural sac when compared with a range of weight-matched breeds. These findings suggest that CKCS could be predisposed to TCS and that spinal cord tethering could be involved in the development of TL SM. Future work is needed to determine whether there is spinal cord tethering in CKCS, potentially through dynamic studies, by consideration of the clinical signs and exploratory surgery  [See, also this June 2018 abstract.]

Syringosubarachnoid shunt placement in a cavalier king charles spaniel dog diagnosed with chiari like malformation and syringomyelia. Case report. Cătălina Anca Cucoş, Ateş Barut, Iuliana Ionaşcu, Radu Constantinescu, Constantin Vlăgioiu. Sci. Works. Series C. Vet. Med. 2018;LXIV(2):29-34. Quote: The aim of this paper was to describe the syringosubarachnoid shunting as surgical management in Chiari like malformation and Syringomyelia, and to track the outcome of the patient. A 4-year-old Cavalier King Charles Spaniel female dog was referred for neurological evaluation due to the intense sudden attacks of pain, occurring more and more often lately. A year earlier, the dog was diagnosed with Chiari-like malformation and syringomyelia, undergoing to a craniocervical decompression with durotomy. Postoperatively the clinical signs improved only for a short period of time, afterwards the clinical symptoms progressively reappeared [progressive neuropathic pain, expressed by sudden yelping, neck and spinal discomfort, scoliosis, apathy and depression. Besides these clinical signs, the patient also presented “phantom” scratching and “bunny-hopping” pelvic limb gait], worsening in the last two months, thus requiring another surgical intervention. The dog was subjected to surgical placement of a syringosubarachnoid shunt at the cervical spinal cord [The maximum syrinx width is located cervical, marking the position where the shunt will be surgically placed. ... The syringosubarachnoid shunt was placed at the level of C3-C4. ... A ventriculoperitoneal catheter was used to create the syringosubarachnoid shunt.], the patient being evaluated periodically during the hospitalization, and after that at one, four and twelve months postoperatively. In the follow-up period the patient presented good results with improvement of the clinical signs. ... At three years after the syringosubarachnoid shunt placement the patient presents an amelioration of the clinical signs comparative to the preoperative period, notably decreased neuropathic pain, the intensity and the frequency of the pain attacks reduced, scratching and yelping diminished, overall increasing the life quality of the patient. ... Syringosubarachnoid shunt placement represents a safe and efficient procedure, which leads to clinical improvement of the clinical signs and reestablishes the quality of life. Syringosubarachnoid shunting can be an alternative option with good results, especially in cases in which foramen magnum decompression has failed.

Magnetic resonance findings in a Cavalier King Charles spaniel with osteopetrosis, Chiari-like malformation and syringomyelia. Ricardo Fernandes, C.J. Jordan, Colin Driver. Vet. Rec. Case Repts. March 2019; doi: 10.1136/vetreccr-2019-000812. Quote: Osteopetrosis (OP) is a rare genetic condition characterised by osteoclast impairment, deficient bone remodelling and increased bone density. Human patients with OP often present with fractures, osteomyelitis, anaemia, abnormal skeletal development, cranial nerve compression and rarely increased intracranial pressure secondary to craniosynostosis and/or calvarial [skull cap] thickening. A 17-month-old male neutered Cavalier King Charles spaniel was presented for evaluation of occasional painful vocalisation. MR of the brain and the vertebral column revealed a rare association of Chiari-like malformation (CLM) and calvarial [skull cap] thickening due to diffuse OP resulting in severe cerebellar compression and herniation into the foramen magnum. ... MR scanning of the brain revealed partial herniation of the cerebellar vermis into the foramen magnum, consistent with Chiari-like malformation (CLM) and several other common associated features such as dilatation of the lateral ventricles and Figure 1Aflattening of the forebrain. There was moderate dilation of the fourth ventricle. The occipital bone was markedly dysplastic and was compressing the caudal and dorsal cerebellum. The skull base appeared abnormally shortened; particularly in the region of the basioccipital bone. The spinal cord was dorsally compressed by the cerebellum and appeared to be ‘kinked’ due to ventral compression from the dens of the axis (figure 1A). There was a marked generalised calvarial thickening that was more noticeable on T1-weighted sequences (figure 1B,C). The bones of the skull and the vertebral bodies demonstrated a reduction of marrow space (figure 1D,E); all bones of the axial skeleton had markedly thickened cortices and markedly reduced medullary canals. On MR sequences of the cervical and thoracolumbar spine, there was diffuse syringomyelia (SM) with syringes extending from C2 to L4 (figure 2A, B). The syrinx was expanding dorsally and laterally towards the dorsal horns of the grey matter at the level of T4, where the syrinx reached its maximum width (4.8 mm). Orthogonal radiographs (Cuattro DR, USA) of the appendicular skeleton revealed markedly thickened cortices and a significant reduction of the volume of the medullary cavities of the long bones (figure 3A, B). ... Surgical treatment (foramen magnum decompression and dorsal laminectomy of C1) was declined by the pet owner. Gabapentin was prescribed for control of neuropathic pain (Gabapentin; Sandoz, 10 mg/kg every eight hours); and cimetidine (Zitac; Intervet, 10 mg/kg every 12 hours) due to its effects on histamine 2 receptors, inhibiting cerebrospinal fluid (CSF) production. The patient demonstrated a good clinical response to the prescribed therapy. The packed cell volume remained reduced but stable until the patient was lost to follow-up 10 months after the initial presentation. ... To the authors’ knowledge, this report represents the first described case of calvarial thickening caused by OP in association with CLM and syringomyelia in veterinary medicine. (See also this September 2018 abstract on the same study.)

Clinical usage of gabapentin in dogs under primary veterinary care in the UK. Lavinia F Mitton, Sandra Sanchis-Mora, Ludovic Pelligand, Holger Volk, David C Brodbelt, Dan G O’Neill. BSAVA Cong. April 2019; p. 478. Quote: Objectives: This retrospective study aimed to explore gabapentin use in dogs in the UK. We aimed to report usage prevalence, conditions treated, therapeutic effectiveness, treatment duration and dose regimens, suspected adverse reactions and accompanying treatments. Methods: The study included 318,922 dogs within the VetCompass™ Program under primary veterinary care in 2016. Data were collected from anonymised electronic medical records. Results: Usage prevalence of gabapentin was 0.44% (95% CI: 0.42–0.47%; n = 1415). Twenty condition types were treated including: spinal pain and/or lesion (31.7%), pain – musculoskeletal (23.9%), osteoarthritis (13.2%), Chiarilike malformation/syringomyelia (4.7%), intervertebral disc disease (4.3%), unspecified neuromuscular signs (4.0%), unspecified pain (3.8%), cruciate disease (2.7%) and seizure(s) (1.9%). Gabapentin was reported to improve clinical signs in 47.3% of dogs. The course duration was generally short term (59.7%; <30 days between first and last dispense) and 59.6% of doses were given twice daily. The prevalence of suspected adverse reactions was 7.85% (95% CI: 6.57%–9.36%; n = 1438) and the most common were sedation (5.2%) and ataxia (1.3%). The most common accompanying treatments alongside gabapentin were non-steroidal anti-inflammatory drugs (27.2%), tramadol (9.0%), glucocorticoids (5.6%) and opioids (4.8%). Statement (Conclusions): This study provides useful benchmarking data on gabapentin usage in primary-care practice and suggests a low occurrence of mild side effects. Despite the subjective nature of the efficacy assessment, gabapentin showed a good therapeutic efficacy. These results can assist practicing clinicians to benchmark their clinical use of gabapentin and to predict suspected adverse reactions.

Rostral skull changes in Cavalier King Charles spaniels with Chiari-like malformation and syringomyelia. Eleonore Dumas, Susan Penny Knowler, Felicity Stringer, Clare Rusbridge. BSAVA Congress 2019 proceeding. April 2019; p. 539. Quote: Objectives: Chiari-like malformation (CM) and secondary syringomyelia (SM) have proven associations to multiple morphological traits of the caudal cranium and cervical spine in Cavalier King Charles Spaniels (CKCS). Since brachycephaly increases risk for disease, this study focused on the morphology of the rostral skull and forebrain and aimed to identify physical features associated to development of CM associated pain (CM-P) and SM with a more severe phenotype. Methods: Analysis of 12 measurements (11 lines and 1 angle) taken on T2 weighted midsagittal MRI of the skull and cervical spinal cord of 66 CKCS enabled the comparison of 3 phenotypic groups: dogs without SM or CM-P (control group; n = 11), dogs with CM-P only (n = 15), dogs with clinically severe CM/SM (syrinx transverse diameter ≥4mm and clinical signs relating to SM; n = 40). Results: SM-affected CKCS had an increased height of the cranium (p = 0.028) and reduced depth of the stop (p = 0.006) compared to controls. SM-affected CKCS also had a significant reduction in height of the nasal cavity compared to CM-P (p = 0.014). There were 2 additional significant traits comparing dogs with and without SM; SM affected dogs had a more ventral orientation of the olfactory bulbs (p = 0.014) and shorter distance between basicranium and hard palate (p = 0.031). Statement (Conclusions): Dogs with symptomatic CM/SM are more likely to have brachycephalic features of the rostral skull with “midface” hypoplasia similar to craniosyostosis Crouzan syndrome. This not only enhances our understanding of the disease and “at risk” head conformation but could also impact assessment of MRI and disease diagnosis.

Prevalence of neurological disorders in Cavalier King Charles Spaniels in neurology referral populations. Katie Brown, Rowena Packer, Holger Volk, Clare Rusbridge. BSAVA Congress 2019 proceedings. April 2019; pp. 538-9. Quote: Objectives: This study aimed to determine the distribution of clinical presentations and the prevalence of neurological conditions in Cavalier King Charles Spaniels (CKCS). A particular focus was placed upon establishing if syringomyelia was a prevalent disease in CKCS and a frequent diagnosis in referral populations. Methods: Records of 500 CKCS presenting to Fitzpatrick Referrals and the Royal Veterinary College neurology departments over a selected four-year period (September 2013– September 2017) were searched. Data was examined to determine the presenting clinical signs and final diagnosis made and analysis was carried out to establish the prevalence and frequency of these. Results: The most common clinical presentations of all neurological conditions were behavioural signs of pain (312 cases; 62.4%), spinal pain (238; 47.6%), phantom scratching (121; 24.2%) and gait abnormalities (90; 18.0%). The most common final diagnosis was syringomyelia (216 affected; 43.2% prevalence), orthopaedic conditions (74; 14.8%) and intervertebral disc disease (60; 12.0%). Other less frequently documented conditions included Chiari-like malformation associated pain (56; 11.2%), myoclonus (19; 3.8%), epilepsy (18;3.6% and skin disease (12; 2.4%). Statement (Conclusions): This study provides vital information for veterinarians, breeders and owners of CKCS about common presentations of syringomyelia and other neurological diseases to allow for earlier recognition of these potentially painful disorders. It concludes that syringomyelia is the most prevalent neurological disease in referral practices and emphasizes the frequency of pain associated with neurological disorders, but when compared to previous studies, it may be underdiagnosed in first opinion practices.

Is CT an alternative to MRI in a morphometric analysis system for prediction of Chiari-like malformation associated pain and syringomyelia? Clare Rusbridge, Angus McFadyen, Felicity Stringer, Susan Knowler. BSAVA Congress 2019 proceedings. April 2019; pp. 503-4. Quote: Objectives: A system of MRI morphometric analysis to predict Chiarilike malformation associated pain (CM-P) and syringomyelia (SM) has been developed. The analysis relies on bony landmarks and computer tomography (CT) of the skull and cervical vertebrae may be useful to predict disease risk i.e. as a more economical pre-breeding screening test. Methods: This proof of principle pilot study compared morphometric analysis between MRI and CT. Medical records over 4 years were searched for dog breeds predisposed to CM-P and SM that had both MRI and CT head imaging. 13 dogs were identified (5 Chihuahua, 7 Cavalier King Charles Spaniels, 1 Griffon Bruxellois). 13 measurements (1 circle, 1 ellipse, 7 lines, 4 angles) were taken on midsagittal T2 weighted MRI and CT images of the skull and cervical spinal cord. Results: ICC Model (2,1) absolute agreement showed very good agreement for 9 measurements (ICC range 0.790–0.987); 3 measurements had some agreement (ICC range 0.585– 0.687) and 1 angle had poor agreement (0.288). Measurements that used bony landmarks had better agreement. Statement (Conclusions): Morphometric analysis to predict risk of CM-P and SM can be applied to CT but refinement will be necessary. This may eventually be useful as a pre-breeding screening test especially if anatomical analysis software is developed. CT is not sensitive for SM and for the foreseeable future any hypothetical CT pre-breeding test for skeletally mature dogs would be combined with MRI from 5 years of age to determine the final CM-P/SM status. All data would be used in an estimated breeding value programme.

Pregabalin for the treatment of syringomyelia-associated neuropathic pain in dogs: A randomised, placebo-controlled, double-masked clinical trial. S.Sanchis-Mora, Y.M.Chang, S.M.Abeyesinghe, A.Fisher, N.Upton, H.A.Volk, L.Pelligand. Vet. J. July 2019; doi: 10.1016/j.tvjl.2019.06.006 Quote: Highlights: • Cavalier King Charles Spaniels with Chiari-like malformation/syringomyelia can have neuropathic pain. • Pregabalin has efficacy in humans with neuropathic pain, and similarly affected dogs could potentially benefit from the drug. • Pregabalin-treated dogs showed improved owner-recorded daily pain scores using a numerical rating scale. • Pregabalin improved mechanical hyperalgesia, cold hyperalgesia at 0°C and cold allodynia at 15°C. • Pregabalin was efficacious for the treatment of neuropathic pain caused by Chiari-like malformation and syringomyelia in dogs. Abstract: Pregabalin is the first-line treatment for neuropathic pain (NeP) in humans. Dogs with Chiari-like malformation and syringomyelia (CM/SM) associated with NeP could benefit from pregabalin. The aim of this study was to evaluate the efficacy of pregabalin for NeP in dogs with CM/SM. ... Nine Cavalier King Charles Spaniels (four males and five females) were recruited for the study from February 2016 to August 2016 (Fig. 2). The median age was 6 years old (range, 1.1–9 years) and the median bodyweight was 9.6 kg (range, 6.6–13.8 kg). All dogs presented with cervical hyperaesthesia on palpation and five dogs showed scratching behaviour, either phantom scratching or making contact with the skin without evidence of skin/ear disease. ... Six dogs had a heart murmur. ... One dog dropped out of the study at day 7 of the first period due to an ailment unrelated to the study. ... Eight dogs with symptomatic CM/SM were included in a double-masked, randomised, crossover placebo–controlled clinical trial.  ... The pregabalin formulation was the oral solution Lyrica (20 mg/mL, bottle of 473 mL Pfizer). ... All dogs received anti-inflammatory drugs as base-line treatment during placebo or pregabalin phase of 14±4 days each. Analgesic efficacy was assessed with a daily numerical rating scale (NRS) recorded by dog owners (0–10, 10=worst pain) and quantitative sensory testing at baseline, placebo and pregabalin phases. Blood samples were collected to report pregabalin exposure and to assess renal function. Daily NRS scores recorded by dog owners in the pregabalin group were lower than in the placebo group (P=0.006). Mechanical thresholds were higher with pregabalin compared to baseline or placebo (P=0.037, P<0.001). Cold latency at 15°C was prolonged on the neck and humeri with pregabalin compared to baseline (P<0.001 for both) or placebo (P=0.02, P=0.0001). Cold latency at 0 °C was longer on pregabalin compared to baseline and placebo (P=0.001, P=0.004). There was no pregabalin accumulation between first and last dose. This study demonstrates the efficacy of pregabalin for the treatment of NeP due to CM/SM on daily pain scores recorded by dog owners. Pregabalin significantly reduced mechanical hyperalgesia, cold hyperalgesia (0°C) and allodynia (15°C) compared to placebo. Pregabalin was non-cumulative and well tolerated with occasional mild sedation.

Identifying and Treating Neuropathic Pain in Dogs with Syringomyelia. Ashley C. Hechler. Master's thesis, Ohio State Univ. July 2019. Quote: Syringomyelia (SM) is a debilitating condition in the cavalier King Charles spaniel (CKCS) that results in neuropathic pain and diminished quality of life. Von Frey aesthesiometry (VFA) is a method of mechanical quantitative sensory testing that provides an objective sensory threshold (ST) value and can be used to quantify neuropathic pain and monitor response to therapy. The utility of VFA has been previously established in client-owned dogs with acute spinal cord injury and osteoarthritis but the technique has not been evaluated in dogs with SM. The goal of this study was to evaluate ST, as determined by VFA, in dogs with and without SM, to assess the utility of VFA in quantifying NP in SM-affected dogs. We hypothesized the SM-affected CKCS would have lower ST values consistent with hyperesthesia, when compared to control CKCS. Additionally, we hypothesized that ST values in SM-affected dogs would be inversely correlated with syrinx size on MRI and with owner-derived clinical sign scores. ST values for the thoracic and pelvic limbs differed significantly between SM-affected and control CKCS (p=0.027; p=0.0396 respectively). Median ST value (range) for the thoracic limbs was 184.1 grams (120.9-552) for control dogs, and 139.9 grams (52.6-250.9) for SM-affected dogs. The median ST value (range) for the pelvic limbs was 164.9 grams (100.8-260.3) in control dogs and 129.8 grams (57.95-168.4) in SM-affected dogs. The ST values in SM-affected dogs did not correlate with syrinx height on MRI (r=0.314; p=0.137). Owner-reported clinical sign scores showed an inverse correlation with pelvic limb ST values, where dogs with lower ST values (hyperesthesia) were reported by their owners to display more frequent and severe clinical signs (r=-0.657; p=0.022). ST values were lower in SM-affected CKCS compared to control dogs, suggesting the presence of neuropathic pain. Dogs with lower ST pelvic limb values were perceived by their owners to have more severe clinical signs classically associated with SM. Our results suggest that VFA may offer an objective assessment of neuropathic pain in SM-affected dogs and could be useful for monitoring response to therapy in future clinical studies. (See also this September 2019 ACVIM Forum abstract.)

Behavioral and clinical signs of Chiari-like malformation-associated pain and syringomyelia in Cavalier King Charles spaniels. Clare Rusbridge, Angus K. McFadyen, Susan P. Knower. J. v. Intern. Med. July 2019; doi: 10.1111/jvim.15552 Quote: Background: Diagnosis of Chiari-like malformation-associated pain (CM-P) or clinically relevant syringomyelia (SM) is challenging. We sought to determine common signs. ... The aim of this study was to characterize retrospectively the clinical and behavioral signs of CM-P and SM and relate these to maximum syrinx transverse diameter. It is with a view to translating this data into a tool which can be used in prospective studies into the treatment, diagnosis, and genetics of CM/SM. ... Animals: One hundred thirty client-owned Cavalier King Charles spaniels with neuroaxis magnetic resonance imaging (MRI) and diagnosis of CM-P/SM. Dogs with comorbidities causing similar signs were excluded with exception of otitis media with effusion (OME). Methods: Retrospective study of medical records relating signalment, signs, and MRI findings. Dogs were grouped by SM maximum transverse diameter (1 = no SM; 2 = 0.5-1.99 mm; 3 = 2-3.9 mm: 4 = ≥4 mm). Differences between all groups—groups 1 versus 2-4 and groups 1-3 versus 4—were investigated. Continuous variables were analyzed using 2-sample t-tests and analysis of variance. Associations between categorical variables were analyzed using Fisher's exact or chi-square tests. Results: Common signs were vocalization (65.4%), spinal pain (54.6%), reduced activity (37.7%), reduced stairs/jumping ability (35.4%), touch aversion (30.0%), altered emotional state (28.5%), and sleep disturbance (22%). Head scratching/rubbing (28.5%) was inversely associated with syrinx size (P = .005), less common in group 4 (P = .003), and not associated with OME (P = .977). Phantom scratching, scoliosis, weakness, and postural deficits were only seen in group 4 (SM ≥4mm; P = .004). ... Our results suggest any tool developed for ascertaining quality of life in CM-P and SM should have specific questions on signs suggesting discomfort, scratching/rubbing (including character/site), sensitivity to touch, activity, ability to jump and climb stairs, emotional state, and sleep. The study further suggests that SM-specific signs are phantom scratching, scoliosis, and sensory and motor signs that can be related to spinal cord damage by the syrinx and are associated with large syringes (transverse width ≥4 mm). Non-SM-specific signs include vocalization (described as without obvious trigger, when shifting position when recumbent and when being lifted under the sternum to a height), spinal pain, head and ear rubbing or scratching, aversion to touch, refusal or difficulty jumping or doing stairs, exercise intolerance/reduced activity, sleep disruption, or behavioral change described as becoming more anxious, timid, aggressive, or withdrawn. These non-SM-specific signs could reflect CM-P. Although possible variables for the tool have been identified, interrelationships between them would have to be taken into account in a multivariate sense when modeling. ... Conclusions and Clinical Importance: Signs of pain are common in CM/SM but are not SM-dependent, suggesting (not proving) CM-P causality. Wide (≥4 mm) SM is associated with signs of myelopathy and, if the dorsal horn is involved, phantom scratching (ipsilateral) and torticollis (shoulder deviated ipsilateral; head tilt contralateral). (See also this April 2018 abstract.)

Network analysis of canine brain morphometry links tumour risk to oestrogen deficiency and accelerated brain ageing. Nina M. Rzechorzek, Olivia M. Saunders, Lucy V. Hiscox, Tobias Schwarz, Katia Marioni-Henry, David J. Argyle, Jeffrey J. Schoenebeck, Tom C . Freeman. Nature Scientific Repts. August 2019;9:12506. Quote: Structural 'brain age' is a valuable but complex biomarker for several brain disorders. The dog is an unrivalled comparator for neurological disease modeling, however canine brain morphometric diversity creates computational and statistical challenges. Using a data-driven approach, we explored complex interactions between patient metadata, brain morphometry, and neurological disease. Twenty-four morphometric parameters measured from 286 canine brain magnetic resonance imaging scans [25 (8.7%) cavalier King Charles spaniels] were combined with clinical parameters to generate 9,438 data points. Network analysis was used to cluster patients according to their brain morphometry profiles. ... CKCS dogs were distinguished by their ventricular parameters and cerebellar compression. ... Interestingly, 21 of 25 CKCS dogs in our cohort had intact septa, despite their high prevalence of Chiari-like malformation. Conceptually, a compromised septum might increase ventricular compliance and thus explain why Boxers are at low risk of Chiari-like malformation and syringomyelia, despite shared ventricular morphology with CKCSs. ... Canine gliomas occur most commonly in brachycephalic breeds, with the Boxer at highest risk. We noted a significant enrichment of brain tumours with Boxers, however the absence of tumour diagnoses in CKCS dogs resulted in non-enrichment of tumours within our brachycephalic category. ... Our findings suggest that advanced brain ageing enhances brain tumour risk in dogs and may be influenced by oestrogen deficiency-a risk factor for dementia and brain tumours in humans. Morphometric features of brain ageing in dogs, like humans, might better predict neurological disease risk than patient chronological age.

CSF omeprazole concentration and albumin quotient following high dose intravenous omeprazole in dogs. M. Giroda, F. Allerton, E. Vangrinsven, A.C. Tutunaru, J. de Marchin, C. Gómez-Fernández-Blanco, A. Ruiz-Nuño, A. Wojnicz, F. Farnir, K. Gommeren, D. Peeters. Res. in Vet. Sci. August 2019; doi: 10.1016/j.rvsc.2019.07.009. Quote: Clinical signs of syringomyelia and hydrocephalus occur secondary to cerebrospinal fluid (CSF) accumulation within the central nervous system. Omeprazole is recommended to treat these conditions despite little evidence of its capacity to decrease CSF production in the dog. Studies into new treatments are hampered by difficulties in measuring CSF production. The albumin quotient (QAlb), the ratio between CSF and serum albumin concentrations, may reflect CSF production and any decrease in CSF production should be associated with an increase in QAlb. The primary objective of this study was to determine CSF omeprazole concentration after administration of a high intravenous dose of omeprazole and to evaluate its impact on QAlb in the dog. The second aim was to validate QAlb as a surrogate marker of CSF production. Eighteen dogs were included in this prospective crossover placebo-controlled study. Each dog received omeprazole (10 mg/kg), acetazolamide (50 mg/kg) combined with furosemide (1 mg/kg) and saline. Blood and CSF samples were obtained on day 0 and then every 7 days, one hour after drug administration. Omeprazole concentrations (2.0 ± 0.4 μmol/L) reached in CSF after high dose omeprazole were lower than the concentrations previously described as decreasing CSF production in dogs. There was no significant increase in QAlb following administration of acetazolamide/furosemide, prohibiting validation of QAlb as a surrogate marker for CSF production. Several dogs presented transient mild side effects after injection of acetazolamide/ furosemide. High dose omeprazole was well tolerated in all dogs. ... Administration of a high dose of omeprazole produced CSF omeprazole concentrations lower than those previously reported to be effective at reducing CSF production in dogs. The administration of acetazolamide in combination with furosemide was not associated with an increase in QAlb one hour after administration when compared to placebo administration. This suggests a lack of sensitivity of QAlb as a surrogate marker of CSF production in dogs.

Mechanical Quantitative Sensory Testing in Cavalier King Charles Spaniels with and without Syringomyelia. Ashley Hechler, Eric Hostnik, Laurie Cook, Lynette Cole, Sarah Moore. J. Vet. Intern. Med. September 2019;doi: 10.1111/jvim.15597;#NO1:107. Quote: Syringomyelia (SM) is a debilitating condition in cavalier King Charles spaniels (CKCS) resulting in clinical signs of neuropathic pain, such as hyperesthesia and allodynia. Currently, advances in disease treatment are hindered by lack of quantitative ways to assess neuropathic pain and monitor response to therapy. We evaluated an electronic Von Frey aesthesiometer (VFA; IITC Systems) to quantify sensory threshold (ST) abnormalities in SM. We hypothesized that SM-affected dogs would have lower ST than controls, consistent with hyperesthesia, and that ST would inversely correlate with syrinx height and clinical signs scores. Twenty-nine CKCS with (n = 19) and without (n = 10) SM were enrolled. ST was measured by a single investigator, blinded to disease status. ST was compared between groups using Wilcoxin rank-sum. Associations between ST, clinical signs, and imaging findings were evaluated by linear regression. Median ST (range) for the thoracic limbs was 184.1 grams (120.9 - 552) for control, and 139.9 grams (52.6 - 250.9) for SM-affected dogs. Median ST for the pelvic limbs was 164.9 grams (100.8 - 260.3) in control, and 129.8 grams (57.95 - 168.4) in SM-affected dogs. ST for the thoracic and pelvic limbs was lower in SM-affected dogs (p = 0.027; p = 0.0396), suggestive of hyperesthesia. ST in SM-affected dogs did not correlate with syrinx height (r = 0.314; p = 0.137). Pelvic limb ST was inversely correlated with owner-derived clinical sign scores, where dogs with lower ST displayed more severe clinical signs (r = -0.657; p = 0.022). Our results suggest that VFA may offer an objective assessment of hyperesthesia in SM-affected dogs and could be useful in future studies to monitor response to therapy. (See also this July 2019 abstract.) (See also this March 2020 article.)

Using machine learning to understand neuromorphological change and image-based biomarker identification in Cavalier King Charles Spaniels with Chiari-like malformation-associated pain and syringomyelia. Spiteri, M., Knowler, S.P., Rusbridge, C., Wells, K. J. Vet. Intern. Med. September 2019; 10.1111/jvim.15621 . Quote: Background: Chiari-like malformation (CM) is a complex malformation of the skull and cranial cervical vertebrae potentially resulting in pain and secondary syringomyelia (SM). CM associated pain can be challenging to diagnose. ["Machine-learning" is a process of a computer not explicitly programmed by people, which looks for patterns and data, then analyzes that information and draws conclusions and makes predictions from that gathered information.] We propose a machine learning approach to characterize morphological changes in dogs that may/may not be apparent to human observers. This data driven approach can remove potential bias (or blindness) that may be produced by a hypothesis driven expert observer approach. Hypothesis/Objectives: Using a novel machine learning approach to understand neuromorphological change and to identify image-based biomarkers in dogs with CM associated pain (CM-P) and symptomatic SM (SM-S), with the aim of deepening the understanding on these disorders. Animals: 32 client owned Cavalier King Charles Spaniels (CKCS) (11 controls, 10 CM-P, 11 SM-S). Methods: Retrospective study using T2W midsagittal DICOM anonymized images which were mapped to a images of a average clinically normal CKCS reference using Demons image registration. Key deformation features were automatically selected from the resulting deformation maps. A kernelized Support Vector Machine was used for classifying characteristic localized changes in morphology. Results: Candidate biomarkers were identified with receiver operating characteristic (ROC) curves with area under the curve (AUC) of 0.78 (sensitivity = 82%; specificity = 69%) for the CM-P biomarkers collectively, and an AUC of 0.82 (sensitivity = 93%; specificity = 67%) for the SM biomarkers collectively. Conclusions and clinical importance: Upon comparing dogs with CM-P to a control group, the main regions identified as diagnostically relevant candidate biomarkers for this condition are: the floor of the third ventricle and closely associated neural tissue, and the region in sphenoid bone (pre-sphenoid and basisphenoid) around the sella turcica. There are also lesser areas of interest in caudal nasal cavity close to the dorsal cribriform plate, between the soft palate and the tongue, on the tip of the odontoid process. The main regions were identified as diagnostically relevant biomarkers when comparing dogs with a specific diagnosis of SM to a control group are: the pre-sphenoid bone and the region between the soft palate and the tongue. It is worth noting that both experiments have yielded biomarkers in the presphenoid bone and area between the soft palate and the tongue, which indicates both conditions being strongly related to changes within this area. Further work will explore the further development of the image registration process, which in turn is expected to improve the AUC values. This study has shown we can successfully discriminate between CM-P subjects and those without, and for those with SM-S, and those without, using a set of biomarkers discovered using machine learning. This work can be used as a basis to build a clinical diagnostic test based on registering these key locations in a query subject back to the equivalent landmarks on a reference subject free of such pathology. Further analysis could be done to investigate whether a link exists between disease severity and the magnitude of the neuro-morphological distortion indicated by these biomarkers. Developing these biomarkers into a clinical diagnostic test is the topic of on-going work.

Facial changes related to brachycephaly in Cavalier King Charles Spaniels with Chiari‐like malformation associated pain and secondary syringomyelia. Susan P. Knowler, Eleonore Dumas, Michaela Spiteri, Angus K. McFadyen, Felicity Stringer, Kevin Wells, Clare Rusbridge. J. Vet. Intern. Med. November 2019; doi: 10.1111/jvim.15632. Quote: Background: Recent studies including an innovative machine learning technique indicated Chiari-like malformation (CM) is influenced by brachycephalic features. Objectives: Morphometric analysis of facial anatomy and dysmorphia in CM-associated pain (CM-P ) and syringomyelia (SM) in the Cavalier King Charles Spaniel (CKCS). Animals: Sixty-six client-owned CKCS. Methods: Retrospective study of anonymized T2W sagittal magnetic resonance imaging of 3 clinical groups: (1) 11 without central canal dilation (ccd) or SM (CM-N), (2) 15 with CM-P with no SM or <2 mm ccd (CM-P), and (3) 40 with syrinx width ≥4 mm (SM-S). Morphometric analysis assessed rostral skull flattening and position of the hard and soft palate relative to the cranial base in each clinical group and compared CKCS with and without SM‐S. Results: Sixteen of 28 measured variables were associated to SM-S compared to CM-N and CM-P. Of these 6 were common to both groups. Predictive variables determined by discriminant analysis were (1) the ratio of cranial height with cranial length (P<.001 between SM-S and CM-N) and (2) the distance between the cerebrum and the frontal bone (P<.001 between SM-S and CM-P). CM-P had the lowest mean height of the maxillary area. Conclusions and Clinical Importance: CKCS with CM-P and SM-S have cranial brachycephaly with osseous insufficiency in the skull with rostral flattening and increased proximity of the hard and soft palate to the cranial base. Changes are greatest with CM-P. These findings have relevance for understanding disease pathogenesis and for selection of head conformation for breeding purposes.

Figure 5


2020

Pregabalin alleviates clinical signs of syringomyelia-related central neuropathic pain in Cavalier King Charles Spaniels – a randomised controlled trial. Maria S. Thoefner, Lene T. Skovgaard, Fintan J. McEvoy, Mette Berendt, Ole J. Bjerrum. Vet. Anaesth. & Analgesia. March, 2020;47(2):238-248. Quote: Objective: We aimed to assess the efficacy and benefit-risk profile of pregabalin to reduce the clinical signs of central neuropathic pain as reflected by scratching episodes in dogs with symptomatic syringomyelia. Study design: Randomized, double-blind, placebo-controlled crossover study. Animals: A total of 12 client-owned Cavalier King Charles Spaniels (1.1-7.4 years old, bodyweight 8.2-10.8 kg) with magnetic resonance imaging-confirmed syringomyelia and clinical signs of central neuropathic pain. Methods: Randomization of dogs to either pregabalin 150 mg or placebo for 25 days and 48-hours wash-out before crossover to the alternate phase of 25 days duration. The primary outcome was defined as number of scratching events during 10 minutes of video recorded physical activity. Treatment effect was estimated using a generalised estimation equations model. Benefit-risk and quality of life assessments were obtained through owner interviews focusing on potential adverse events. Results: The treatment effect estimate was an 84% (95% confidence interval = 75%-89%) reduction in mean number of scratching events relative to baseline when compared to placebo (p < 0.0001). Owner-assessed satisfactory quality of life was status quo and rated as ‘good’ or ‘could not be better’ in 6/11 dogs and improved in 4/11 dogs. The most prevalent adverse events were increased appetite in 9/12 dogs and transient ataxia in 9/12 dogs. There was one dog withdrawn by the owner 7 days after crossover to pregabalin owing to persistent ataxia. No dogs needed rescue analgesia during the trial. Conclusion and clinical relevance: Pregabalin is superior to placebo in the reduction of clinical signs of syringomyelia-related central neuropathic pain in dogs. At a dose range of 13–19 mg kg-1 orally twice daily the encountered adverse events were acceptable to all but one owner.

Mechanical quantitative sensory testing in cavalier King Charles spaniels with and without syringomyelia. Ashley C. Hechler, Eric T. Hostnik, Laurie B. Cook, Lynette K. Cole, Sarah A. Moore. BMC Vet. Res. March 2020; dio: 10.1186/s12917-020-02313-7. Quote: Background: Syringomyelia (SM) is a debilitating condition in the cavalier King Charles spaniel (CKCS) that results in neuropathic pain and diminished quality of life. Von Frey aesthesiometry (VFA) is a method of mechanical quantitative sensory testing that provides an objective sensory threshold (ST) value and can be used to quantify neuropathic pain (NP) and monitor response to therapy. The utility of VFA has been previously established in client-owned dogs with acute spinal cord injury but the technique has not been evaluated in dogs with SM. The goal of this study was to evaluate ST, as determined by VFA, in dogs with and without SM, to assess the utility of VFA in quantifying NP in SMaffected dogs. We hypothesized the SM-affected CKCS would have lower ST values, consistent with hyperesthesia, when compared to control CKCS. Additionally, we hypothesized that ST values in SM-affected dogs would be inversely correlated with syrinx size on MRI and with owner-derived clinical sign scores. ... Nineteen 19 SM-affected [MRI evidence] and 10 control CKCSs [no MRI evidence of SM] were enrolled. ... Control dogs ranged from 1 to 2 years of age (median 1.5 years) and SM-affected dogs ranged from 1 to 8 years of age (median 4 years). SM-affected dogs were significantly older than control dogs, but the sex did not differ significantly between groups. ... Results: ST values for the thoracic and pelvic limbs differed significantly between the SM-affected and control CKCS. Median ST value (range) for the thoracic limbs was 184.1g (120.9–552) for control dogs, and 139.9g (52.6–250.9) for SM-affected dogs. The median ST value (range) for the pelvic limbs was 164.9g (100.8–260.3) in control dogs and 129.8g (57.95–168.4) in SM-affected dogs. The ST values in SM-affected dogs did not correlate with syrinx height on MRI (r=0.314;p=0.137). Owner-reported clinical sign scores showed an inverse correlation with pelvic limb ST values, where dogs with lower ST values (hyperesthesia) were reported by their owners to display more frequent and severe clinical signs. Conclusion: ST values were lower in SM-affected CKCS compared to control dogs, suggesting the presence of neuropathic pain. Dogs with lower ST pelvic limb values were perceived by their owners to have more severe clinical signs classically associated with SM. Our results suggest that VFA might offer quantitative assessment of neuropathic pain in SM-affected dogs and could be useful for monitoring response to therapy in future clinical studies. (See also this September 2019 abstract.)

The effect of phenotypic selection on fourteen years of chiari-like malformation and syringomyelia MRI scanning in Cavalier King Charles Spaniels in the Netherlands. Laterveer, M. Utrecht Univ. master thesis. March 2020. Quote: Chiari-like malformation (CM) and Syringomyelia (SM) is an inherited disease complex which is common in the Cavalier King Charles Spaniels (CKCS). Since 2004 a law-enforced obligatory screening program prior to breeding is used to achieve a healthier population of Dutch CKCS. This study evaluated the effect of phenotypic selection by combining pedigree data and screening results of two to three generations of dogs to see if there is any improvement in the breeding stock. In total, 572 MRI scans from 518 dogs were prospectively enrolled if they were screened between January 1st 2016 and December 31st 2018. CM and PSOM (primary secretory otitis media) were scored and SM was defined as unaffected (CCD (central canal dilation) of 0 mm) or affected (CCD of >0 mm). The prevalence of SM in this study was 22.7% and increased with age clearly demonstrating the age-effect of SM. The prevalence of middle ear effusion in the left ear was 19.4% and in the right ear 20.0%. Results indicated that selecting unaffected parents leads to a lower CCD in offspring. This reduction in CCD is even more if parents with healthier grandparents are given priority. Conversely, the offspring of affected parents was more likely to have an increase in CCD. CM and PSOM did not improve upon screening for unaffected parents. It is concluded that, the obligatory screening for and subsequent selection for older unaffected CKCS, the offspring indeed improved each generation and as indicated by a reduced prevalence of Syringomyelia.

Medical infrared thermal imaging of syringomyelia in the Cavalier King Charles Spaniel. Michael Larkin, Catherine Loughin, Dominic Marino, Curtis Dewey, Scott Umbaugh, Joseph Sackman. BMC Vet. Res. May 2020;16:137. doi: 10.1186/s12917-020-02354-y  Quote: Background: Medical infrared thermal imaging (MITI), also known as medical infrared imaging (MII) or infrared thermography (IRT), is a noninvasive imaging modality used for screening purposes in human medicine and gaining popularity in veterinary medicine. ... MITI requires use of a specific camera that captures emission of heat from the surface of objects, such as skin. Topical heat emission is influenced by localized disease processes as a result of autonomic nervous system imbalance. The purpose of this study was to determine the utility of using thermography to identify changes in thermographic patterns associated with syringomyelia (SM) presence or absence in Cavalier King Charles Spaniels (CKCS) with Chiari-like Malformation (CLM). ... One hundred dogs were included in this study. Due to poor image quality (usually motion artifact) preventing proper interpretation on some of the MITI images, seven of the dogs were eliminated totaling 93 CKCS in this study. Of the 93 CKCS included, the average age was 33.7 months old (SD = 27.4 months) and the average weight of each patent was 8.1kg (17.8 pounds). There were 35 female intact (37.6%), 24 female spayed (25.8%), 15 male intact (16.1%) and 19 male neutered (20.4%) CKCS. Of the 93 CKCS included in this study, all (100%) had CLM based on complete, full-body MR imaging; 48 (51.6%) were diagnosed with SM and 45 (48.4%) had no evidence of SM. ... Results: In CKCS with CLM, MITI was most accurate at a texture distance of 6. Optimizing imaging feature sets produced a highest accuracy of 69.9%, with 81.3% sensitivity and 57.8% specificity for identifying the presence of syringomyelia. Conclusion: Thermographic image analysis is a successful non-invasive, diagnostic test that can be used to screen for syringomyelia presence in a CKCS with CLM. ... This study revealed that MITI is a successful screening test for the presence of SM in CKCS with CLM. Compared to other imaging modalities, MITI is a quick, inexpensive modality that does not require sedation nor anesthesia, and eliminates radiation exposure (to patient & staff). MITI does not provide insight to syrinx location or severity nor should it be used as a sole diagnostic modality. While veterinary thermographic imaging continues to improve as advances in technology occur, MRI will remain the gold standard for definitive diagnosis and staging of Chiari-like malformation and syringomyelia. (Fig. 1 -- Thermograms of CKCS: Left image is CKCS without SM; right image is CKCS with SM.)

Figure 1

Comparison of high-field MRI and multidetector CT for grading Chiari-like malformation and syringomyelia in Cavalier King Charles Spaniels. Sarah M Weber, Eric T Hostnik, Wm Tod Drost, Alessandra N Hamlin, Marc A Ledesma, Lauren Timperman, Ashley C. Hechler, Lynette K Cole. Vet. Radiol. & Ultrasound. April 2020;doi: 10.1111/vru.12862. Quote: Chiari-like malformation (CM) and syringomyelia (SM) are common illnesses that can cause debilitating neuropathic pain in Cavalier King Charles spaniels (CKCS). The current imaging modality to screen CKCS for CM/SM is MRI of the brain and cervical spine. Magnetic resonance imaging provides good soft tissue detail and contrast of the cerebellum and cervical spinal cord. Computed tomography (CT) is another cross-sectional imaging technique that facilitates brain and neck evaluation; however, soft tissue resolution does not match that of MRI. Computed tomography benefits include identification of concurrent craniocervical junction anomalies (atlantooccipital overlap) and shorter imaging/ anesthesia times with the ability to use only sedation. The aim of this retrospective, method comparison study is to assess the utility of multidetector CT for screening CM and SM in CKCS as compared to high-field MRI. Three groups of observers with different levels of experience graded CM and SM based on the British Veterinary Association/Kennel Club CM/SM classification criteria. Thirty CKCS underwent multidetector CT and 3 Tesla MRI studies. Computed tomography and MRI studies were reviewed at different timepoints to minimize bias. Computed tomography has lower Cohen's Kappa agreement for each observer group compared to MRI. The intraclass correlation coefficient averaging CM and SM for all groups was excellent using MRI, while CT was poor for SM and moderate for cerebellar herniation. ... Computed tomography is financially cheaper, shorter in acquisition time, more accessible to general practitioners, and requires less anesthetic drugs/time. Results of this study support the hypothesis that the overall agreement and the agreement between observer groups of similar experience levels is higher using 3T MRI compared to multidetector CT. The second hypothesis related to sensitivity, specificity, and accuracy had mixed results. The average sensitivity and accuracy for diagnosis of cerebellar herniation and SM using MRI was higher than CT. ... The higher accuracy, though only slight, using CT for identifying cerebellar herniation counters our hypothesis that MRI is a better tool for CM evaluation. The lower inter-rater agreement for diagnosis of cerebellar herniation using CT relative to MRI indicates that though accuracy is slightly higher, the observers were not arriving to the same consensus regarding each individual case. Also, the slight difference in accuracy may not be a clinically significant difference. The more accurate identification of SM using MRI does support the hypothesis of MRI as a better tool for identifying neural pathology. ... The specificity for identifying cerebellar herniation was similar between MRI and CT. The average specificity for identifying SM was higher using CT compared to MRI. The third hypothesis regarding experience was not completely supported by the results. Sensitivity, specificity, and accuracy for MRI of DACVR [radiology diplomate] B, as well as the average sensitivity, specificity, and accuracy for CT findings of the ACVR observers were higher than the lesser-experienced groups of observers. However, the average sensitivity, specificity, and accuracy of the veterinary interns and secondyear residents were similar with the veterinary interns slightly higher than the residents. ... Greater observer experience resulted in a higher agreement for CT and MRI. Magnetic resonance imaging should remain the standard for screening of CM and SM as CT can result in misclassification and greater disagreement.

Figure 2

New considerations about Chiari-like malformation, syringomyelia and their management. Clare Rusbridge. InPractice. June 2020;42(5):252-267; doi: 10.1136/inp.m1869 Quote: Background: Chiari-like malformation (CM) is a developmental condition, characterised by a conformational change and overcrowding of the brain and cranial cervical spinal cord. CM-associated pain (CM-P) and syringomyelia are increasingly being diagnosed, due to the rising popularity of predisposed brachycephalic breeds and the availability of MRI in veterinary practices. Aim of the article: This article aims to update the veterinary profession on these conditions, and provides a guide to diagnosis and treatment of clinically relevant disease. ... The condition is most common in Cavalier King Charles spaniels (CKCS) and their crosses (eg, cavapoos), especially if the cross is with a smaller dog than a CKCS.

Retrospective Study of 240 Dogs Receiving Gabapentin for Chronic Pain Relief. Lily V Davis, Peter W Hellyer, Robin A Downing, Lori R Kogan. J. Vet.Med. & Research. August 2020;7(4):1194-1197. Quote: Our goal was to assess gabapentin dosage and tolerability in dogs taking it for chronic pain. ... All patients in this study were on gabapentin due to an inability to fully control their pain with NSAIDs or nutraceuticals alone. ... The majority (217 patients; 90.42%) had pain localized to their back. The other anatomic locations of pain included stifle (33; 13.8%), elbow/shoulder (21; 8.8%) and hip (11; 4.6%). Some patients’ pain was localized to multiple areas and is counted in all categories. The most common diagnosis of pain was osteoarthritis (203; 84.6%), followed by generalized, nonspecific back pain (22;9.2%), intervertebral disk disease (18; 7.5%), and degenerative myelopathy (11; 4.6%). Some patients experienced two different kinds of pain and are embodied in both categories. One hundred and thirty-six (56.67%) patients did not have definitive anatomic cause for their pain, such as cruciate tears or intervertebral disc disease, as seen in Table 2. ... We retrospectively analyzed the medical records of 240 dogs taking gabapentin for chronic pain and systematically assessed: patient signalment, definitive diagnosis, location and description of pain, VAS scores immediately preceding and following the patient’s maximum gabapentin dose, maximum gabapentin dosage, presence or absence of side effects related to gabapentin use, use of NSAID/immunomodulator drugs and nutraceuticals, presence or absence of levothyroxine supplementation, surgical procedures, and physical medicine. The range of tolerated gabapentin doses was 6.9 - 500 mg/kg/day [3.1- 227.3 mg/lb], PO, q12 hr (every 12 hrs) and only 10% of patients experienced the most common side effect of sedation. ... The results from this case series suggest that gabapentin is well-tolerated at much higher doses than what is typically prescribed. Side effects were uncommon, with no clear pattern based on dose, or dog size or age. Therefore, like many other analgesic medications, the efficacy of gabapentin appears patient-specific and should be dosed to effect until side effects are noted or analgesia is achieved.

The effect of combined carprofen and omeprazole administration on gastrointestinal permeability and inflammation in dogs. Susan M. Jones, Ann Gaier, Hiroko Enomoto, Patricia Ishii, Rachel Pilla, Josh Price, Jan Suchodolski, Joerg M. Steiner, Mark G. Papich, Kristen Messenger, M. Katherine Tolbert. J. Vet. Intern. Med. September 2020; doi: 10.1111/jvim.15897. Quote: Background: Proton pump inhibitors (eg, omeprazole) commonly are administered concurrently with nonsteroidal anti-inflammatory drugs (NSAIDs; eg, carprofen) as prophylaxis to decrease the risk of gastrointestinal (GI) injury. However, evidence to support this practice is weak, and it might exacerbate dysbiosis and inflammation. Hypothesis/Objectives: To evaluate the effect of carprofen alone or combined with omeprazole in dogs. We hypothesized that coadministration of omeprazole and carprofen would significantly increase GI permeability and dysbiosis index (DI) compared to no treatment or carprofen alone. Animals: Six healthy adult colony beagle dogs. Methods: Gastrointestinal permeability and inflammation were assessed by serum lipopolysaccharide (LPS) concentration, plasma iohexol concentration, fecal DI, and fecal calprotectin concentration in a prospective, 3-period design. In the first 7-day period, dogs received no intervention (baseline). During the 2nd period, dogs received 4 mg/kg of carprofen q24h PO for 7 days. In the 3rd period, dogs received 4 mg/kg of carprofen q24h and 1 mg/kg of omeprazole q12h PO for 7 days. Gastrointestinal permeability testing was performed at the end of each period. Data were analyzed using repeated measures mixed model analysis of variance with Tukey-Kramer post hoc tests. Results: Serum LPS and plasma iohexol concentrations did not differ between treatments. Fecal calprotectin concentrations differed between treatments. The DI varied over time based on the treatment received. Co-administration of omeprazole and carprofen significantly increased fecal calprotectin concentration and DI compared to baseline and carprofen alone. Conclusions and Clinical Importance: Omeprazole prophylaxis induces fecal dysbiosis and increases intestinal inflammatory markers when coadministered with carprofen to otherwise healthy dogs with no other risk factors for GI bleeding. ... The increase in fecal DI when dogs were given carprofen and omeprazole PO suggests that addition of omeprazole had a negative impact on the fecal microbiome, and in turn may negatively impact intestinal health. ... Whether carprofen plays a substantial role in the induction of dysbiosis or inflammation when coadministered with omeprazole cannot be determined from our study because we did not include a treatment group in which dogs received omeprazole alone. ... [Other studies have shown that] Carprofen-induced injury to the gastroduodenal mucosa is generally mild and resolves quickly after drug discontinuation. ... Based on previous studies in which omeprazole caused intestinal dysbiosis in dogs and the lack of dysbiosis or inflammation with carprofen alone in our study, we believe that omeprazole is the major driver of fecal dysbiosis and intestinal inflammation and, although further study is needed, may result in development of NSAID-induced enteropathy, as previously determined in other species.

Clinical reasoning in canine cervical hyperaesthesia: which presenting features are important. Nicholas John Grapes, Rowena Mary Anne Packer, Steven De Decker. Vet. Rec. November 2020; doi: 10.1136/vr.105818. Quote: Background: To evaluate whether clinical features from the history, presentation, physical and neurological examination of dogs with cervical hyperaesthesia are statistically predictive of the underlying diagnosis. Methods: Two hundred and ninety‐eight dogs presenting with cervical hyperaesthesia between January 2010 and October 2018 were investigated. ... The study population consisted of 54 diferent breeds with 38 crossbreeds. The most prevalent breeds were Cavalier King Charles spaniels (n=49), French bulldogs (n=31), beagles (n=27), labradors (n=18) and cocker spaniels (n=10). Of the French bulldogs within the study population, 84 per cent (n=26) were diagnosed with IVDE, while 88 per cent (n=43) of Cavalier King Charles spaniels studied were diagnosed with SM [syringomyelia]. ... Only neurologically normal dogs with cervical hyperaesthesia on examination were included, while those with concurrent neurological deficits including gait abnormalities and proprioceptive deficits were excluded. Univariate analysis of clinical variables was performed, and those associated with each diagnosis were retained for multivariable binary logistic regression models. Results: Ninety-five per cent of cervical hyperaesthesia presentations were represented by eight conditions that included steroid-responsive meningitis arteritis (SRMA; n=100 - 33.6%), intervertebral disc extrusion (n=78 - 26.2%), syringomyelia (SM; n=51 - 17.1%), intervertebral disc protrusion (n=30 - 10.1%), neoplasia (n=8 - 2.7%), cervical spondylomyelopathy (n=7 2.3%), immune‐mediated polyarthritis (n=5 - 1.7%) and meningoencephalomyelitis of unknown aetiology (n=5 - 1.7%). ... 88 per cent of Cavalier King Charles spaniels presenting with cervical hyperaesthesia during the study period were diagnosed with SM. SM was most commonly episodic in its progression. Although the most obvious clinical signs to the owner such as phantom scratching or vocalisation may be intermittent or episodic, recent research has identiied that persistent signs of discomfort including reduced activity, reluctance to jump or climb stairs, emotional changes and aversions to being touched are common in dogs with Chiari-like malformation and SM. ... Conclusions: Easy-to-recognise clinical features can be used to identify the most likely differential diagnosis in neurologically normal dogs with cervical hyperaesthesia, which may aid the decision making of veterinary surgeons evaluating dogs with this presentation.

Quantification of cerebrospinal fluid flow in dogs by cardiac-gated phase-contrast magnetic resonance imaging. Muriel A. Christen, Daniela Schweizer-Gorgas, Henning Richter, Fabiola B. Joerger, Matthias Dennler. J. Vet. Intern. Med. December 2020; doi: 10.1111/jvim.15932. Quote: Background: Cerebrospinal fluid (CSF) flow in disease has been investigated with two-dimensional (2D) phase-contrast magnetic resonance imaging (PC-MRI) in humans. Despite similar diseases occurring in dogs, PC-MRI is not routinely performed and CSF flow and its association with diseases is poorly understood. Objectives: To adapt 2D and four-dimensional (4D) PC-MRI to dogs and to apply them in a group of neurologically healthy dogs. Animals: Six adult Beagle dogs of a research colony. Methods: Prospective, experimental study. Sequences were first optimized on a phantom mimicking small CSF spaces and low velocity flow. Then, 4D PC-MRI and 2D PC-MRI at the level of the mesencephalic aqueduct, foramen magnum (FM), and cervical spine were performed. Results: CSF displayed a bidirectional flow pattern on 2D PC-MRI at each location. Mean peak velocity (and range) in cm/s was 0.92 (0.51-2.08) within the mesencephalic aqueduct, 1.84 (0.89-2.73) and 1.17 (0.75-1.8) in the ventral and dorsal subarachnoid space (SAS) at the FM, and 2.03 (range 1.1-3.0) and 1.27 (range 0.96-1.82) within the ventral and dorsal SAS of the cervical spine. With 4D PC-MRI, flow velocities of >3 cm/s were visualized in the phantom, but no flow data were obtained in dogs. Conclusion: Peak flow velocities were measured with 2D PC-MRI at all 3 locations and slower velocities were recorded in healthy Beagle dogs compared to humans. These values serve as baseline for future applications. The current technical settings did not allow measurement of CSF flow in Beagle dogs by 4D PC-MRI.

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2021

Association between filum terminale internum length and pain in Cavalier King Charles spaniels with and without syringomyelia. Courtney R. Sparks, Christian Woelfel, Ian Robertson, Natasha J. Olby. J. Vet. Intern. Med. January 2021; doi: 10.1111/jvim.16023. Quote: Background: Lumbar syringomyelia (SM), lumbosacral pain, and more caudal spinal cord termination are reported in Cavalier King Charles spaniels (CKCS). Data are lacking on the clinical relevance of alterations in their spinal cord terminal structures. ... The normal spinal cord tapers to a relatively elastic structure called the filum terminale internum, composed of ependymal, pial and glial cells and surrounded by the subarachnoid space and dural sac. Distally, the dural sac closes down onto the filum, creating a more fibrous tether, called the filum terminale externum. This structure fuses with the periosteum of the caudal (Cd) vertebrae, thus anchoring the meninges and spinal cord within the vertebral canal. ... Objectives: To compare spinal cord termination level and filum terminale internum length (FTIL) with presence of lumbar SM and clinical signs in CKCS. Animals: Forty-eight CKCS. ... Twenty-three of 48 dogs (48%) did not have SM, 2 dogs had cervical SM only (4%), 1 dog had lumbar SM only (2%), and 22 dogs had both cervical and lumbar SM (46%). All dogs with lumbar SM also had thoracic SM. The cohort consisted of 16 (33%) normal dogs, 12 (25%) asymptomatic dogs with SM, 7 (15%) symptomatic dogs without SM (CM-pain), and 13 (27%) symptomatic dogs with SM.  ... Methods: In this prospective study, pain was quantified using owner and clinician assessments. ... We hypothesized that symptomatic CKCS with CM with or without SM would have a significantly more caudal termination of their spinal cord than do asymptomatic dogs. Our aims were first to describe and compare the site of spinal cord and dural sac termination in symptomatic and asymptomatic CKCS, and second to quantify and compare the length of the filum terminale internum between these 2 groups of dogs. ... Vertebral level of spinal cord and dural sac termination, presence of SM, and FTIL were determined from sagittal magnetic resonance imaging (MRI) sequences. Kappa and intraclass correlation (ICC) analyses determined interobserver reliability. The MRI findings were compared to owner and clinician-reported pain quantification. Results: Interobserver reliability was good for spinal cord and dural sac termination and excellent for FTIL. The spinal cord terminated at 6th lumbar vertebra in 1, 7th lumbar vertebra in 31, and the sacrum in 15 dogs, and termination level was associated with lumbar SM but not clinical signs. Mean FTIL was 2.9 ±1.08 mm; it was associated with owner-reported pain and spinal palpation scores. Painful CKCS without SM had shorter FTIL compared to normal CKCS and painful CKCS with SM. Conclusions: Painful CKCS without SM have decreased distance between the termination of the spinal cord and dural sac, suggesting a shorter FTIL. More caudal spinal cord termination is associated with development of lumbar SM. ... In summary, the purpose of our work was to determine if caudal spinal abnormalities in CKCS were associated with clinical signs of pain and scratch. We disproved our hypothesis that a more caudal location of spinal cord termination would be associated with clinical signs. However, we found that FTIL is associated with pain, not scratch, and our work supported previous findings that the vertebral level of the spinal cord termination is associated with lumbar SM. In addition, we found that painful dogs without SM were differentiated from other phenotypes by a decreased FTIL. These findings show that location of the filum terminale is associated with development of lumbar SM and FTIL is associated with spinal pain in CKCS. Future work is warranted to characterize other caudal clinical and functional abnormalities, potentially by use of gait analysis, electro-physiological evaluation of the conus medullaris, and urodynamic studies in these dogs. (See also this June 2018 abstract.)

Frequency of phantom scratching in Cavalier King Charles Spaniels (CKCS) assessed by owner questionnaire before and during maropitant treatment. Emma Gilbert, Sandra Sanchis Mora, Ludovic Pelligand, Lydia Poad, Holger Volk, Clare Rusbridge. BSAVA Congress 2021: Clinical abstract presentation. January 2021; doi: 10.22233/9781913859039.26. Quote: Study basis: The superficial dorsal horn was previously found to be affected in CKCS with syringomyelia with the clinical sign of phantom scratching. The NK-1 receptors located in this area are considered as a target for treatment for fictive [phantom] itch. We aimed to assess outcomes with 2 weeks maropitant treatment (NK-1 R antagonist) on frequency of phantom scratching. Results: Population: 9 CKCS, mean age 6.1 years (range 3-10), 3 males (1 entire, 2 neutered) and 6 females (1 entire, 5 neutered). The most common site that the syrinx involved the superficial dorsal horn was the level of C3 or C4 vertebrae. Following treatment with maropitant mean scores for questions on frequency of phantom scratching decreased. Wilcoxon Rank sign analysis was significant in 4/6 of these questions. Spontaneous scratching, scratching while walking, scratching when groomed, scratching when touched. Discussion: VAS scores were difficult for owners to complete without guidance with only 3/9 being completed (though notably all giving a decreased score consistent with improvement), we therefore excluded them from the results of our study. This trial was open label, and therefore subject to caregiver bias, placebo effect and high owner expectation. Owners were happy with maropitant as a treatment for chronic disease due to its low side effect profile. Further investigation with a placebo controlled crossover study is needed next to confirm this initial evidence for a positive effect to decrease frequency of phantom scratching in dogs and the lack adverse effects found with treatment with this licensed veterinary product.

The Need for Head Space: Brachycephaly and Cerebrospinal Fluid Disorders. Clare Rusbridge, Penny Knowler. Life. February 2021; doi: 10.3390/life11020139. Quote: Brachycephalic dogs and cats are predisposed to cerebrospinal fluid (CSF) circulation disorders, such as ... Chiari-like malformation, and syringomyelia. ... Cavalier King Charles spaniels with syringomyelia associated with Chiari-like malformation have smaller volume jugular foramina compared to Cavalier King Charles spaniels without syringomyelia. However, direct causality between smaller jugular foramen and syringomyelia has not been proven. ... [C]raniosynostosis [premature closure of cranial sutures, preventing continued growth to accommodate the growing size of the brain] may be associated with a primary venous abnormality. Cavalier King Charles spaniels with syringomyelia associated with Chiari malformation have reduced volume caudal cranial fossa dorsal sinuses. ... Chiari-like malformation associated pain in dogs describes a syndrome of pain associated with brachycephaly and hindbrain herniation. It is often compared to Chiari type I and 0 malformation in humans. However, it is more like the hindbrain herniation seen with syndromic and complex craniosynostosis in humans, for example, Crouzon’s and Pfeiffer syndrome. ... In comparison to dogs with Chiari-like malformation only, dogs with syringomyelia have more extreme brachycephaly with craniocervical junction deformation, including cervical flexure, change in angulation of the odontoid peg, increased proximity of the atlas to the skull (often referred to as atlanto-occipital overlapping), kinking or elevation of the craniospinal junction, and loss of the cisterna magna. Changes in conformation of the spinal canal and cord may also contribute. The authors propose that syringomyelia develops due to a combination of reduced CSF absorption though nasal lymphatics, reduced venous drainage, altered neuroparenchymal compliance, and reduced CSF movement through the lateral apertures or craniocervical junction. Curvature of the spinal canal and intrathoracic pressure gradient may contribute especially in the thoracic spinal cord. The mechanism of development of syringomyelia is controversial. The most accepted theory is that subarachnoid space obstruction results in a mismatch in timing between the arterial pulse peak pressure and CSF pulse peak pressure. ... Dogs and cats with neonatal characteristics of a reduced muzzle and brachycephaly have impaired CSF [cerebrospinal fluid] circulation, which predisposes ventriculomegaly, hydrocephalus, quadrigeminal cistern expansion, Chiari-like malformation associated pain, and syringomyelia.

Histologic findings of the dura mater at the level of the foramen magnum in 121 CKCS with Chiari-like malformation. Jaclyn P. Holdsworth, Dominic J. Marino, Catherine A. Loughin, Andrew D. Miller, Joseph J. Sackman, Martin L Lesser, Marissa O’Donnell. ResearchSquare. March 2021; doi: 10.21203/rs.3.rs-314710/v1. Quote: Background: To describe histopathologic features found in dural biopsies of Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation (CM) and identify any associations between age, duration of clinical signs, syrinx location or syringomyelia (SM) and quality of life (QOL). The medical records of 121 consecutive client owned CKCS with CM and SM, confirmed by whole body magnetic resonance imaging (MRI), that underwent foramen magnum decompression (FMD) with cranioplasty and durectomy with biopsy from 2006 to 2016 were retrospectively reviewed. Dura biopsies were submitted to a board-certified veterinary pathologist for histopathologic interpretation. The chi-square test was used to analyze associations between diagnosis and categorical variables. For continuous measures, the Kruskal-Wallis non-parametric test was used to compare distributions across pathology categories. A result was considered statistically significant at the P<0.05 level of significance. Results: The mean age, duration of pre-surgical clinical signs, and pre-operative QOL (1-5 scale) were 44.27 months, 44.78 weeks, and 2.72 respectively. Syringomyelia was found in the cervical region only in thirty-nine of one hundred twenty-one (32.23%) of dogs, in the cervical and thoracic region only in seventeen of one hundred twenty-one (14.05%) of dogs, and in the cervical, thoracic and lumbar region combined in sixty-five of one hundred twenty-one (53.72%) of dogs. Sixty-six of one hundred twenty-one (54.55%) dural biopsy specimens had histopathology changes; fifty-five (45.45%) did not. Forty-three of one hundred twenty-one (35.54%) dural biopsy specimens had osseous metaplasia, sixteen of one hundred twenty-one (13.22%) had evidence of fibrosis, four of one hundred twenty-one (3.31%) had arachnoid hyperplasia, and three of one hundred twenty-one (2.48%) had evidence of mineralization. Conclusions: The majority of dogs with CM were found to have histopathologic changes in the dura at the time of FMD cranioplasty was performed. These dural changes can be observed in dogs experiencing clinical signs for a time period as short as four weeks prior to presentation. Histopathologic changes were not associated with age, breed, duration of clinical signs, the location of syringomyelia or preoperative QOL. The influence of histopathologic changes on long term prognosis in dogs without dural decompression is unknown since all dogs in this study had dural resection.

Syringomyelia and Myxomatous Mitral Valve Disease in Cavalier King Charles Spaniels. Maiken B.T. Bach, C.L. Stougaard, M.S. Thofner, M.J. Reimann, U. Westrup, J. Koch, M. Fredholm, T. Martinussen, M.Berendt, L.H. Olsen. 2021 ACVIM Forum. June 2021; C-12. Quote: Cavalier King Charles spaniels (CKCS) are genetically predisposed to both syringomyelia (SM) and myxomatous mitral valve disease (MMVD). This study investigated if a possible association between the occurrence of the two diseases exists. This combined retrospective and prospective study running 2007-2015 included 55 CKCS: Forty-one dogs with syrinx identified with MRI, defined by a hypointense area in T1 > 2mm in width, and 14 controls ( > 5 years of age) with no syrinx on MRI. Of dogs with SM, 19 dogs were asymptomatic while 22 were symptomatic. Echocardiography ( > 4 years of age) were performed in all dogs. A possible association between syringomyelia and MMVD disease severity (left ventricle internal diameter in diastole (LVIDD), LVIDD normalized to bodyweight (LVIDDN) and left atrium to aortic ration (LA:Ao)) was tested using multivariable linear regression analysis adjusting for sex and age. There was no significant difference in LVIDD, LVIDDN and LA:Ao (median [IQR]) between CKCS with SM (28.20 [27.0–30.80], 1.50 [1.40–1.60], 1.20 [1.10–1.40]) and CKCS without SM (28.90 [27.15–36.75], 1.55 [1.43–1.83], 1.30 [1.20–1.80]). Yet, LVIDD, LVIDDN and LA:Ao were smaller in CKCS with symptomatic SM (27.20 [25.85–28.80], 1.45 [1.30–1.50] and 1.20 [1.10–1.28]) compared to CKCS with asymptomatic SM (30.80 [28.40–38.40] p < 0.001, 1.60 [1.50–1.90] p < 0.001, 1.40 [1.20–1.75]). We found no overall association between MMVD and SM. Dogs affected with symptomatic SM had less severe MMVD compared to dogs with asymptomatic SM indicating it is important to be aware of both diseases when breeding CKCS.

Ventriculomegaly in Cavalier King Charles Spaniels with Chiari-like Malformation: Relationship with Clinical Signs and Imaging Findings. F. Tirrito, F. Cozzi, S. Corazzo, B. Contiero, R. Lombardo. 33d ESVN-ECVN Symposium 2021, #P-30. September 2021. Vet. Intern. Med. December 2021; doi: 10.1111/jvim.16332.  Quote: Chiari-like malformation (CM) frequently occurs in Cavalier King Charles Spaniels (CKCS). Ventriculomegaly, secondary to disturbance of cerebrospinal fluid flow at the craniocervical junction, has been reported in CKCS with CM. However, its clinical relevance is unclear. The aim of the study was to calculate lateral ventricles dimension in CKCS with CM and to investigate the association between ventriculomegaly and signalment, clinical signs, ventricular asymmetry, CM and syringomyelia (SM) grade, medullary kinking index, follow-up, and epileptic seizures. A retrospective study was performed enrolling forty-three client-owned CKCS with magnetic resonance imaging diagnosis of CM. Initial and follow-up (up to 36 months) clinical status was graded. Images were reviewed to quantify dimension of lateral ventricles, to evaluate ventricular symmetry, CM and SM grade, and medullary kinking index. Cases presenting epileptic seizures were also recorded. The most common initial clinical signs were scratching and neck pain. Ventriculomegaly was identified in 70% of dogs, CM grade 2 was observed in 77% of cases, ventricular asymmetry and syringomyelia were identified in 54% and 80% of dogs, respectively; median medullary kinking index was 37.77%. Moreover, 28% of dogs presented epileptic seizures. No significant association was identified between dimension of lateral ventricles and signalment, clinical signs, and imaging findings; no significant association was identified between ventriculomegaly and epilepsy. In conclusion, the prevalence of ventriculomegaly in CKCS with CM is high but this finding does not seem related to the severity of clinical signs, to CM/SM, to medullary kinking index, and to epileptic seizures.

Successful Pain Management after Filum Terminale Internum De-tethering in 2 CKCS with Chiari-like Malformation. Ane Uriarte, Abby McElroy, Petra Klinge. 33d ESVN-ECVN Symposium 2021, #P-79. September 2021. Vet. Intern. Med. December 2021; doi: 10.1111/jvim.16332. Quote: Cavalier King Charles Spaniels (CKCS) are affected by Chiari-like malformation (CM) and syringomyelia (SM) causing neuropathic chronic pain. Severely affected cases fail to respond to medical management and occipital cranioplasty is often recommended. Clinical relapse of neuropathic pain is recorded in a high number of cases treated with this surgical approach. An association between Chiari I malformation (CM1) and tethered cord syndrome in human patients presenting post failed CM1 surgery is recognised (Milhorat et al., 2009). For these patients, de-tethering of the filum terminale internium may be effective in relieving symptomatology, restoring normal brain stem length, normalizing the position of the cerebellar tonsils, and in some cases, avoiding the need for posterior fossa surgery (Milhorat et al 2009). CKCS have a caudally displaced spinal cord and dural sac when compared with a range of weight-matched breeds (Sparks at al., 2019). Additionally, painful CKCS without SM have been found to have a shorter filum terminale internum (Sparks at al., 2020). Two CKCS affected with CM had a successful resolution of pain following de-tethering surgery, including a 7-year-old who relapsed after occipital cranioplasty and a 1-year-old with no previous surgery. The filum terminale internum was sectioned via a dorsal laminectomy without complications and both animals were free of pain, without medication, for 20 and 7 months respectively at the time of writing. Follow up MRI was performed on one dog. De-tethering of the filum terminale internum will remain controversial until definitive treatment guidelines are established in human and veterinary medicine.

Foramen magnum decompression and modified cranioplasty using titanium mesh plate in small dogs with caudal occipital malformation syndrome and syringomyelia. Yukiko Nakano, Y. Nozue, K. Nakata, S. Kimura, H. Kamishina. 33d ESVN-ECVN Symposium 2021, #O-22. September 2021. Vet. Intern. Med. December 2021; doi: 10.1111/jvim.16332. Quote: Foramen magnum decompression (FMD) is one of the surgical treatments of Chiari malformation type 1 in humans. FMD is also a treatment option for caudal occipital malformation syndrome (COMS) and syringomyelia in dogs. Cranioplasty (CP) is combined with FMD to prevent postoperative scar tissue formation that compresses the FMD site. However, adequate decompression may not be achieved in small-breed dogs with reported surgical procedures because of the potential risk of damage of the transvers sinus. We performed modified [much wider] FMD+CP in small-breed dogs [3 chihuahuas and 2 toy poodles] and retrospectively investigated the clinical outcomes and complications. Informed consent was obtained from owners of all dogs prior to surgeries. We performed modified FMD+CP in 5 dogs with COMS and syringomyelia. The occipital bone was removed widely with a great care not to damage the transvers sinus. A pre-contoured titanium mesh plate was placed over the bone defect and secured to the parietal and temporal bones with screws. Procedures were completed without any intraoperative complication in all dogs. Complete resolution of clinical signs was seen in 2 dogs. Cerebellar symptoms such as ataxia and hypermetria remained in three dogs, but QOL of these dogs was improved and the owners were satisfied with the outcome. Three-month postoperative follow-up MRI performed in 3 dogs [all chihuahuas] revealed considerable reduction of the syrinx size. In conclusion, modified FMD+CP is a safe procedure and leads to considerable reduction of the syrinx in small-breed dogs. This procedure is expected to reduce the risk of recurrence of foramen magnum compression and syrinx formation by postoperative scar tissues.

Diffusion Tensor Imaging in Syringomyelia Secondary to Chiari Malformation in Cavalier King Charles Spaniel. Preliminary Study. A. Banasik, Karolina Owsińska-Schmidt, W. Krupińska, A. Zimny, M. Wrzosek. 33d ESVN-ECVN Symposium 2021, #O-21. September 2021. Vet. Intern. Med. December 2021; doi: 10.1111/jvim.16332. Quote: The aim of this study was to find a correlation between clinical assessment and diffusion tensor imaging (DTI) values in the course of Syringomyelia. Sixteen Cavalier King Charles Spaniel dogs, (eight in the symptomatic and eight in the asymptomatic group), 6-70 months of age (mean 36), 3.5-9.5 kg (mean 7.2), were qualified for the research. All animals underwent the same study protocol that included a clinical and neurological examination followed by MRI examination. DTI was performed with a 1,5 Tesla magnetic resonance scanner (Philips, Ingenia). Two DTI parameters: fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured. Measurement of FA and ADC values was made by drawing regions of interest (ROIs) at the level of three intervertebral spaces (C1-C4) in both sympthomatic and asympthomatic group. Image post-processing was done using the Fiber Trak package (Philips Ingenia workstation). Statistical analysis showed no significant differences in FA and ADC values between the symptomatic and asymptomatic groups. However, decreased FA values were observed in ROI-2 and ROI-3 in the symptomatic group compared to the asymptomatic group. Compared to the asymptomatic group, in the symptomatic group in ROI-1 the same ADC values were observed, while in ROI-2 and ROI-3 an increase in ADC values was noted. Findings suggest that DTI could be a helpful technique in the study of syringomyelia in Cavalier King Charles Spaniel, in content of anticipation of eventual development of clinical symptoms in young dogs. DTI values measurements may provide more objective spinal cord microstructure and indirectly also status assessment. (See also this December 2022 article on the same study.)

Slosh Simulation in a Computer Model of Canine Syringomyelia. Srdjan Cirovic, Clare Rusbridge. Life. October 2021; doi: 10.3390/life11101083. Quote: The exact pathogenesis of syringomyelia is unknown. Epidural venous distention during raised intrathoracic pressure (Valsalva) may cause impulsive movement of fluid (“slosh”) within the syrinx. Such a slosh mechanism is a proposed cause of syrinx dissection into spinal cord parenchyma resulting in craniocaudal propagation of the cavity. We sought to test the “slosh” hypothesis by epidural excitation of CSF [cerebrospinal fluid] pulse in a computer model of canine syringomyelia. Our previously developed canine syringomyelia computer model was modified to include an epidural pressure pulse. ... The model geometry was extracted from magnetic resonance imaging (MRI) scans of a CKCS [cavalier King Charles spaniel] with a Chiari-like malformation and a fully developed syrinx. Cardiac pulse excitation of CSF motion was simulated for a fully patent and a fully occluded foramen magnum, with the latter representing the extreme case of CSF pathway obstruction due to Chiari-like malformation. When the foramen magnum was fully patent, the model predicted mechanical stress in the spinal cord to be of the same magnitude as the CSF pressure (order of magnitude of 102 Pa). When the foramen magnum was obstructed, the stress values in the cranial cervical region and the cervico-thoracic junction increased by nearly 100%; these are also the regions where initial syringes form in dogs. While the absolute values of mechanical stress predicted by the model were probably too low to cause any immediate damage to the spinal cord tissue, abnormally high stress was clearly correlated with typical anatomical locations at which syringes initially form. Without trying to explain the exact mechanism(s) for syrinx formation and growth, we hypothesize that they can be associated with the stress in the spinal cord being significantly elevated from the values that would normally be generated by common excitations such as the cardiac pulse and filling of the epidural veins. In this study, we build on the above hypothesis to examine the situation where small initial syringes have already formed in the spinal cord tissue. The focus is on the excitation of CSF movement caused by the filling of epidural veins, which can potentially generate the “slosh” effect leading to syrinx expansion. ... Simulations were run for: cord free of cavities; cord with small syringes at different locations; and cord with a syrinx that was progressively expanding caudally. If small syringes are present, there are peaks of stress at those locations. This effect is most pronounced at the locations at which syringes initially form. When a syrinx is expanding caudally, the peak stress is typically at the caudal end of the syrinx. However, when the syrinx reaches the lumbar region; the stress becomes moderate. The findings support the “slosh” hypothesis, suggesting that small cervical syringes may propagate caudally. However, when the syrinx is large, there is less focal stress, which may explain why a syrinx can rapidly expand but then remain unchanged in shape over years. ... Conclusions: The results of this study strongly suggest that the spinal cord tissue in the vicinity of fluid-filled cavities experiences higher than normal mechanical stress due to the movement of the CSF from epidural excitation. When the syringes are longer than approximately 30 mm, filling of the epidural veins may generate the “slosh” effect, where the fluid is forced to the caudal end of the syrinx. The results for the simulations of an expanding syrinx are broadly consistent with the homeostatic hypothesis, as the stress in the cord is lower for the fully developed syrinx than for smaller syringes. Other, potentially more realistic, scenarios for syrinx expansion should be examined in the future. This study specifically addresses syringomyelia in dogs, and more specifically in CKCS. ... Considering anatomical and other differences (e.g., upright posture in humans) the results regarding the potential pattern of syrinx enlargement do not apply to humans or to dog breeds other than CKCS.

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2022

Occipital cranioplasty using customized titanium prosthesis yields successful outcome in association with foramen magnum decompression in dogs suffering by Chiari-like malformation. Alessia S. Colverde, Tommaso Nicetto, Cristian Falzone. Am. J. Vet. Res. February 2022; doi: 10.2460/ajvr.21.11.0178. Quote: Objective: To describe the use of a customized 3–D-printed titanium prosthesis as adjunctive treatment for foramen magnum decompression (FMD) in dogs with Chiari-like malformation (CM) and syringomyelia (SM). Animals; 8 dogs [6 cavalier King Charles spaniels  (75%)] with clinical signs and MRI findings of CM-SM. Procedures: 3-D reconstruction of CT images of the head was used to simulate an occipital craniectomy and design the prosthesis. [See figures A and B.] FMD was performed, and the prosthesis was implanted. 3-D reconstructionFollow-up was performed 1, 6, and 12 months later, and clinical status was scored. Repeated MRI images were compared to identify changes involving the neural structures, particularly the syrinx. Results: All prostheses were easily positioned based on the preoperative 3-D models, with no complications. At 12 months after surgery, 3 dogs were free of previous medications [CKCS Cases 2, 3, & 7], 4 were still receiving steroid medications but at lower doses [CKCS Cases 5 & 6], and 1 was occasionally receiving acupuncture. MRI of 5 dogs 6 to 20 months after surgery revealed resolution of SM (n = 1) [CKCS Case 7], reduced size of SM (3) [CKCS Cases 2 & 4], or worse SM (1) [CKCS Case 6]. ...
Case 2: CKCS female intact, age 34 months: On presentation: Chiari-malformation (CM) grade 2 (cerebellum impacted or herniated through foramen magnum (FM); syrinx (SM) location & size: C2-C4, 5 mm.; clinical signs: Grade 2 (mild neuropathic pain); duration of clinical signs: 1 year; post-surgery results: 1 month follow-up: Grade 0 (no pain and phantom scratching); 6 month follow-up: Grade 0; 12 month follow-up: Grade 0; 47 month follow-up: Grade 0; MRI follow-up at 20 months: CM: 0; SM: C2-C3, 3.5 mm.
Case 3: CKCS female intact, age 25 months: On presentation: CM grade 1 (cerebellum indented, not rounded); SM location & size: C3, 1.2 mm.; clinical signs: Grade 3 (moderate neuropathic pain); duration of clinical signs: 2 months; Grade 3 (moderate neuropathic pain) on presentation; 1 month follow-up: Grade 0; 6 month follow-up: Grade 0; 12 month follow-up: Grade 0; 40 month follow-up: Grade 0; no MRI follow-up.
Case 5: CKCS female intact, age 21 months: On presentation: CM grade 2; syrinx (SM) location & size: C2-C5, 4 mm.; clinical signs: Grade 2; duration of clinical signs: 10 months; post-surgery results: 1 month follow-up: Grade 0; 6 month follow-up: Grade 1; 12 month follow-up: Grade 1; 31 month follow-up: Grade 1; no MRI follow-up.
Case 6: CKCS female intact, age 36 months: On presentation: CM grade 2; syrinx (SM) location & size: C2-L1, 5.7 mm.; clinical signs: Grade 3; duration of clinical signs: 2 years; post-surgery results: 1 month follow-up: Grade 0; 6 month follow-up: Grade 1; 12 month follow-up: Grade 1; 23 month follow-up: Grade 3; MRI follow-up at 19 months: CM: 0; SM: C1-L1, 6.4 mm.
Case 7: CKCS female neutered, age 48 months: On presentation: CM grade 2; syrinx (SM) location & size: C3-C4, 5.7 mm.; clinical signs: Grade 3; duration of clinical signs: 1.5 years; post-surgery results: 1 month follow-up: Grade 0; 6 month follow-up: Grade 0; 12 month follow-up: Grade 0; 16 month follow-up: Grade 0; MRI follow-up at 9 months: CM: 0; SM: none.
Case 8: CKCS male neutered, age 77 months: On presentation: CM grade 2; syrinx (SM) location & size: C2-L5, 7.3 mm.; clinical signs: Grade 4 (severe neuropathic pain); duration of clinical signs: 5 years; post-surgery results: 1 month follow-up: Grade 1; 6 month follow-up: Grade 1; 12 month follow-up: Grade 1; no MRI follow-up. ...
All dogs showed an increase in size of the caudal cranial fossa. Dogs with a longer presurgical duration of the clinical signs and wider syrinx generally had worse outcomes than other dogs. Clinical Relevance: Findings suggested that use of customized 3–D-printed titanium prosthesis and associated FMD can represent an adjunctive option to medically treated dogs with CM-SM. Although the small number of cases precludes definitive conclusions, early surgical treatment, particularly in dogs with a small syrinx, could ensure better long-term outcomes, as previously suggested.

Nasal Septum Deviation in dog breeds predisposed to Chiari-like malformation associated pain and syringomyelia. Clare Rusbridge, J. R. Rusbridge. BSAVA Congress 2022. March 2022. Quote: Nasal Septum deviation in breeds predisposed to Chiari-like malformation associated pain and syringomyelia. Objectives: Nasal septum deviation (NSD) and Chiari-like malformation pain and syringomyelia (CMSM) are common in flat-faced brachycephalic dogs. NSD may be clinically irrelevant but has been associated with sleep disordered breathing (SDB) in humans and dogs. SDB affects glymphatic drainage of cerebrospinal fluid which could predispose CMSM. This study investigated possible correlation between NSD and CMSM Methods Study population - 76 dogs with head CT [computed tomography] and known CMSM status (based on MRI and medical history). Comprising 53 CKCS [cavalier King Charles spaniels] (70%) (7 CM-N [CM-clinically normal] i.e. MRI determined breed-associated CM but clinically normal; 14 with CM-P [CM-associated pain] but no SM; 32 with SM); 12 Chihuahua (5 MRI and clinically normal, 7 with SM); 11 other brachycephalic toy dog breeds and crosses (10 with SM). Transverse CT of the nasal cavity in bone windows was reviewed. Presence of a NSD was recorded. Previously described method of determining the angle of NSD was not reproducible and consequently abandoned. The NSD ratio calculated (maximum distance of NSD from midline/ distance from midline to nasal cavity wall). Results NSD was almost ubiquitous; Only 3 dogs had a midline nasal septum without deviation (1 Chihuahua, 1 CKCS, 1 Cavapoo; all 3 were CMSM affected). There was no correlation between NSD ratio and CMSM (signs of pain or presence of syringomyelia). Impact NSD is common in dog breeds predisposed to CMSM. Care should be taken before attributing clinical relevance. Association of NSD to CMSM is unproven. More extreme brachycephaly is associated with both NSD, CM-P and SM and therefore the conditions may co-exist. Airway obstruction, SDB and apnoea may be relevant in the pathogenesis of CMSM or be a important comorbidity. More sophisticated methods of investigation are recommended for example polysomnography to monitor respiratory effort.

Dorsal horn volume loss and pain pathway changes in Cavalier King Charles Spaniels with syringomyelia, signs of pain, and phantom scratching. Danny Mortensen, Maria Soendergaard Thoefner, Joergen Steen Agerholm, Lasse Slumstrup, Troels Staehelin Jensen, Ole Jannik Bjerrum, Mette Berendt, Jens Randel Nyengaard. Pain. March 2022; doi: 10.1097/j.pain.0000000000002630. Quote: Central neuropathic pain is a core clinical sign of syringomyelia in humans and Cavalier King Charles Spaniel (CKCS) dogs. This histopathological study used spinal cords from CKCS with syringomyelia to investigate: 1) whether specific structural cervical spinal cord entities involved in nociception are affected by loss of neuroparenchyma or other pathological changes in CKCS with pain-related behaviour and phantom scratching, 2) if pain related behaviour or phantom scratching correlated with loss of a specific anatomical entity or upregulation of glia cells, and 3) if syringomyelia-related lesions affected specific functional spinal cord units of nociception. Spinal cord segments C1-C8 from CKCS with MRI-confirmed syringomyelia and clinical signs of pain and phantom scratch (n=8) were compared to CKCS without syringomyelia (n=4). Dogs with unilateral scratching (n=7) had a volume loss of the dorsal horn laminae I-III in the ipsilateral side compared to the contralateral dorsal horn. A clear pattern of ipsilateral changes in the dorsal root entry zone characterised by deafferentation and reorganization of first-order axons into deeper laminae was found in cases with lateralised scratching. Significant changes in cell number density were not found for astrocytes or microglia, suggesting that the dogs represented cases of end-stage syringomyelia and thus could not reveal astrogliosis and microgliosis, which may be involved in the early phases of syrinx development and phantom scratch. The present relationship between clinical findings and dorsal horn and pain pathway pathology in CKCS suggests that these dogs may be of interest as a supplement to experimental model pain research.

Ventriculomegaly in Cavalier King Charles Spaniels with Chiari-like malformation: relationship with clinical and imaging findings. Federica Tirrito, Francesca Cozzi, Martina Bonaldi, Stefania Corazzo, Barbara Contiero, Rocco Lombardo. J. Vet. Med. Sci. July 2022; doi: 10.1292/jvms.22-0134. Quote: The objective of this study was to calculate lateral ventricles dimension in Cavalier King Charles Spaniel dogs with Chiari-like malformation and investigate the association between ventriculomegaly and signalment, clinical signs, ventricular asymmetry, grade of Chiari-like malformation, syringomyelia and index of medullary kinking. Retrospectively, 43 client-owned Cavalier King Charles Spaniels, older than 1 year of age, with magnetic resonance imaging diagnosis of Chiari-like malformation were enrolled. ... Twenty-eight (65%) dogs were male and 15 (35%) were female. The percentage of male dogs was significantly higher than females. ... Initial and follow-up (up to 36 months) clinical status was graded. Images were reviewed to quantify the enlargement of lateral ventricles, evaluate ventricular symmetry, grade of Chiari-like malformation, grade of syringomyelia and medullary kinking index. Cases presenting epileptic seizures during the evaluation period were also recorded. The most common initial clinical signs were scratching and neck pain. Ventriculomegaly was identified in 70% of dogs, Chiari-like malformation grade 2 [(CM2); cerebellum impacted or herniated through the foramen magnum] was observed in 77% of cases, ventricular asymmetry and syringomyelia were identified in 54% and 80% of dogs, respectively; the median medullary kinking index was 37.77%. Moreover, 28% of dogs presented epileptic seizures. ... No significant association was identified between grade of SM and class of ventriculomegaly. ... No significant association was identified between dimension of lateral ventricles and signalment, clinical signs, and imaging findings; no significant association was identified between ventriculomegaly and epilepsy. ... Finally, no significant association was found between medullary kinking index and class of ventriculomegaly in our population of dogs. ... Primary secretory otitis media [OME] is frequently described in CKCS and the reported clinical signs may be similar to those described in dogs with CM. Interestingly, no relationship between OME and clinical signs was found in our population. These results are concordant with previous literature and it is possible that otitis media is a consequence of the brachycephalic conformation of CKCS, but the clinical significance of the disease is unclear. ... In conclusion, the prevalence of ventriculomegaly in Cavalier King Charles Spaniels is high but this finding does not seem related to the severity of clinical signs, presence of Chiari-like malformation, syringomyelia and craniocervical junction abnormalities such as medullary kinking. 2023

Biopsy and histologic findings of the dura mater at the level of the foramen magnum in 121 CKCS with Chiari-like malformation. Jaclyn P. Holdsworth, Dominic J. Marino, Catherine A. Loughin, Andrew D. Miller, Joseph J. Sackman, Martin L. Lesser, Marissa O’Donnell. Front. Vet. Sci. September 2022; doi: 10.3389/fvets.2022.954092. Quote: To describe histopathologic features found in dural biopsies of Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation (CM) and identify any associations between age, duration of clinical signs, syrinx location or syringomyelia (SM), and quality of life (QOL). The medical records of 121 consecutive client owned CKCS with CM and SM, confirmed by whole body magnetic resonance imaging (MRI), that underwent foramen magnum decompression (FMD) with cranioplasty and durectomy with biopsy from 2006 to 2016 were retrospectively reviewed. Dural biopsies were submitted to a board-certified veterinary pathologist for histopathologic interpretation. The chi-square test was used to analyze associations between histologic findings and categorical variables. For continuous measures, the Kruskal–Wallis non-parametric test was used to compare distributions across pathology categories. A result was considered statistically significant at the p < 0.05 level of significance. The mean age, duration of pre-surgical clinical signs, and pre-operative QOL (1–5 scale) were 44.27 months, 44.78 weeks, and 2.72, respectively. Syringomyelia was found in the cervical region only in 39 of 121 (32.23%) of dogs, in the cervical and thoracic region only in 17 of 121 (14.05%) of dogs, and in the cervical, thoracic, and lumbar region combined in 65 of 121 (53.72%) of dogs. Sixty-six of one hundred twenty-one (54.55%) dural biopsy specimens had histopathology changes; fifty-five (45.45%) did not. Forty-three of one hundred twenty-one (35.54%) dural biopsy specimens had osseous metaplasia, 16 of 121 (13.22%) had evidence of fibrosis, 4 of 121 (3.31%) had arachnoid hyperplasia, and 3 of 121 (2.48%) had evidence of mineralization. Most dogs with CM were found to have histopathologic changes in the dura at the time of FMD cranioplasty was performed. These dural changes can be observed in dogs experiencing clinical signs for a time period as short as 4 weeks prior to presentation. The histopathologic changes were not associated with age, breed, duration of clinical signs, the location of syringomyelia or QOL. The influence of histopathologic changes on long-term prognosis in dogs without dural decompression is unknown since all dogs in this study had dural resection.

Diffusion Tensor Imaging in Syringomyelia Secondary to Chiari Malformation in Cavalier King Charles Spaniel — A Preliminary Study. Marcin Adam Wrzosek, Aleksandra Ewa Banasik, Karolina Owsińska‐Schmidt, Anna Zimny. Animals. December 2022; doi: 10.3390/ani12233405. Quote: Syringomyelia secondary to Chiari‐like malformation (so‐called CM‐SM syndrome) is a common disorder in Cavalier King Charles Spaniels (CKCS) that is diagnosed using standard structural MRI, though imaging findings often do not correlate with the severity of clinical symptoms. Diffusion tensor imaging (DTI) is a technique that defines subtle microstructural changes in the course of many brain and spinal cord diseases, that are not visible on standard MRI. The aim of the study was to identify the correlation between the presence of clinical symptoms and DTI parameters, such as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) within the spinal cord in the course of CM-SM. ... To our knowledge, this is the first report evaluating DTI parameters in dogs with syringomyelia use in the clinical setting. ... We hypothesized that DTI would be a good candidate for prediction regarding the prevalence of the symptomatic CM-SM course and that this would be of great value in canine and human patients. ... Study subjects included 18 dogs, CKCS with MRI‐confirmed SM (SM group), and 12 CKCS dogs without SM (non-SM group). The SM group was divided into SM‐symptomatic group (n = 8) and SM-asymptomatic group, n = 10). All dogs underwent same clinical and neurological assessment followed by MRI examination. All MRI studies were performed on a 1.5T MRI scanner. The MRI spine protocol included: transverse and sagittal T2-weighted images followed by DTI performed in the sagittal plane. The measurements of FA and ADC values were performed manually using the region of interest (ROI) method at the level of three intervertebral discs between C1 and C4. Notable differences in age and body weight were found. No significant differences in FA and ADC values between the SM and non-SM groups were found, but between non- SM, SM-asymptomatic and SM-symptomatic groups significant differences were found in ADC values in all three ROIs and in FA values in ROI-1 and ROI-3. SM-symptomatic dogs compared to no-- SM, showed decreased FA value in ROI-1 and ROI-3 also increased ADC value in ROI-1, ROI-2 and ROI-3. SM-symptomatic dogs compared to SM-asymptomatic showed also decreased FA value in ROI-1 and ROI-3, and also increased ADC value in ROI-1, ROI-2 and ROI-3. The results suggest that the values of DTI parameters correlate with the severity of clinical symptoms in the course of CMSM in animals. The use of DTI evaluation of CM-SM patients carries a potential value as a clinically relevant protocol for an objective assessment of the spinal cord. (See also this September 2021 article on the same study.)

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2023

Three-dimensional kinematics of the craniocervical junction of Cavalier King Charles Spaniels compared to Chihuahuas and Labrador retrievers. Mareike-Kristin Nickel, Lisa Schikowski, Martin Stephan Fischer, Nicola Kelleners, Martin Jürgen Schmidt, Nele Eley. PLoS ONE. January 2023; doi: 10.1371/journal.pone.0278665. Quote: Our knowledge about the underlying pathomechanisms of craniocervical junction abnormalities (CCJA) in dogs mostly derives from measurements based on tomographic imaging. These images are static and the positioning of the dogs’ head does not reflect the physiological in vivo position of the craniocervical junction (CCJ). Aberrant motion patterns and ranges of motion (ROM) in sound individuals of CCJA predisposed breeds may be a pathogenetic trigger. To further extend our limited knowledge of physiological motion of the CCJ, this prospective, comparative study investigates the in vivo motion patterns and ROM of the CCJ in walk and trot in [15] sound Cavalier King Charles Spaniels and [15] Chihuahuas. The Labrador retriever [14 of them] is used as a reference breed without predisposition for CCJA. This is the first detailed description of CCJ movement of trotting dogs. Biplanar fluoroscopy images, recorded in walking and trotting dogs, were matched to a virtual reconstruction of the skull and cranial cervical spine utilising Scientific Rotoscoping. ... Scientific Rotoscoping is a markerless and therefore non-invasive kinematic gait analysis method of XROMM methodology (X-Ray Reconstruction of Moving Morphology). The technique merges motion data from biplanar X-ray videos with skeletal morphology data from CT scans and creates 3D bone animations moving in 3D space. Scientific Rotoscoping is considered a methodology generating anatomically highly accurate animations, also for use in dogs and the spine in particular. Highly precise and accurate motion measurements are enabled, although the technique is very elaborate and time consuming. ... Kinematic data reveal the same motion patterns among all breeds and gaits with individual temporal and spatial differences in each dog. A stride cycle-dependent lateral rotation of the cranial cervical spine and axial rotation of the atlantoaxial joint in trot in dogs is described for the first time. The ROM of the atlantoaxial and atlantooccipital joints in walk and trot were not statistically significantly greater in the CCJA-predisposed breeds CKCS and Chihuahua. ROM values of all translational and rotational degrees of freedom were larger in walk than trot, although this is only statistically significant for the atlantoaxial joint. Until proven otherwise, a more species-specific than breed-specific general motion pattern of the CCJ in walking and trotting, clinically sound dogs must be assumed. Species-specific anatomic properties of the CCJ seem to supersede breed-specific anatomical differences in clinically sound dogs.

Chiari-like malformation in Cavalier King Charles Spaniels impacts brainstem auditory-evoked response latency results. Lynette K. Cole, Susan O. Wagner, Sarah A. Moore, Ronaldo DaCosta, Eric T. Hostnik, Laura E. Selmic. Am. J. Vet. Res. May 2023; doi: 10.2460/ajvr.23.03.0064. Quote: Objective: To evaluate hearing loss in Cavalier King Charles Spaniels (CKCS), breed-specific brainstem auditory-evoked response (BAER) testing parameters are needed to help assess the Chiari-like malformation (CM) grade. The purpose of this study was to establish breed-specific BAER data and to determine if BAER indexes differed based on the CM grade. We hypothesized that there would be latency differences based on the CM grade. Animals: 20 CKCS without apparent hearing abnormalities as assessed by the owners. Procedures: Under general anesthesia, CKCS underwent a CT scan (to assess the middle ear), BAER testing, and MRI (to assess the grade of CM). Results: No CKCS had CM0. Nine (45%) CKCS had CM1; 11 (55%) had CM2. All had at least 1 morphologic abnormality in waveforms. Absolute and interpeak latencies were reported for all CKCS and compared between CM grades. The median threshold for CKCS with CM1 was 39 and for CM2 was 46. Absolute latencies for CKCS with CM2 were consistently longer than those for CKCS with CM1 with the exception of waves II and V at 33 dB. Significant differences were found for wave V at 102 dB ( P = .04) and wave II at 74 dB (P = .008). Interpeak latency comparisons were inconsistent between CM1 and CM2. Clinical Relevance: Breed-specific BAER data for CKCS with CM1 and CM2 were established. The results suggest that CM impacts BAER latency results, but the influence of the malformation is not always statistically significant or predictable. ... Our study established breed-specific data of BAER measures for CKCS with CM1 and CM2. Specifically, we now have BAER data of absolute and interpeak latencies, as well as the threshold in CKCS based on CM grade. In addition, wave V latency intensity function was constructed with respect to CM grade that can be utilized to assess the presence and type of hearing loss in the CKCS. ... In conclusion, BAER data in CKCS with respect to CM grade have been established. BAER indexes differed based on CM grade in CKCS, but the influence of the grade of the malformation, be it CM1 or CM2, is not always statistically significant or predictable.

Reduced cingulate gyrus volume in Cavalier-King-Charles-spaniels with syringomyelia and neuropathic pain revealed by voxel-based morphometry - a pilot study. Björn Nitzsche1, Sabine Schulze, Johannes Boltze, Martin J. Schmidt. Front. Neuroanat. July 2023; doi: 10.3389/fnana.2023.1175953. Quote: Objective: Pathomorphological alterations of the central nervous system in dogs such as syringomyelia and Chiari-like malformation can cause cranial and cervical hyperesthesia and neuropathic pain. Long term activity of the pain network can induce functional alteration and eventually even morphological changes in the pain network. This may happen especially in the prefrontal- and cingulate cortex where atrophy of the gray matter (GM) was observed in humans with chronic pain, irrespective of the nature of the pain syndrome. We tested the hypothesis that Cavalier King Charles Spaniels (CKCS) with Chiari-like-malformation and associated syringomyelia (SM) and pain show cerebral morphological differences compared to animals without signs of syringomyelia and pain. Methods: Volumetric datasets of 28 different brain structures were analyzed in a retrospective manner, including voxel-based morphometry, in magnetic resonance imaging data obtained from 41 dogs. Results: Volumetric analyses revealed a decrease of GM volumes in the cingulate gyrus (CG) in CKCS with SM and chronic pain when normalized to brain volume. This finding was supported by voxel-based morphometry which showed a cluster of significance within the CG. Conclusion: GM atrophy in the CG is associated with chronic pain and thus may serve as an objective readout parameter for the diagnosis or treatment of canine pain syndromes.

Tolerability of long-term cannabidiol supplementation to healthy adult dogs. Isabella Corsato Alvarenga, Kim M. Wilson, Stephanie McGrath. J. Vet. Intern. Med. November 2023; doi: 10.1111/jvim.16949. Quote: Background: Cannabidiol (CBD) has therapeutic potential in companion animals. Shorter-term studies have determined that CBD is well tolerated in dogs with mild adverse effects and an increase in alkaline phosphatase (ALP) activity. There is need to assess CBD's long-term tolerability. Hypothesis: Determine the long-term tolerability of CBD administered PO to healthy dogs for 36 weeks at dosages of 5 and 10 mg/kg body weight (BW)/day. Our hypothesis was that CBD would be well tolerated by dogs. Methods: Eighteen healthy adult beagle dogs were randomly assigned to 3 groups of 6 each that received 0, 5, or 10 mg/kg BW/day CBD PO. Dogs were adapted to their housing for 3 weeks and received treatment for 36 weeks once daily with food. Adverse events (AEs) were recorded daily. Blood biochemistry profiles were monitored every 4 weeks. Data were analyzed as repeated measures over time using a mixed model, with significance at α = 0.05. Results: The 0 and 5 mg/kg treatment groups had similar fecal scores, and the 10 mg/kg treatment group had higher frequency of soft feces. No other significant AEs were noted. An increase (P < .0001) in ALP activity occurred in groups that received CBD. Remaining blood variables were within reference range. Conclusions and Clinical Importance: Chronic administration of CBD in healthy dogs at 5 mg/kg was better tolerated than 10 mg/kg, and both dosages caused an increase in ALP activity. Although our data does not indicate hepatic damage, it is recommended to monitor liver function in dogs receiving CBD chronically.

Phenotypic characterization of Pomeranians with or without Chiari-like malformation and syringomyelia. Koen M. Santifort, Ines Carrera, Kenny Bossens, Paul J. J. Mandigers. Front. Vet. Sci. December 2023; doi: 10.3389/fvets.2023.1320942. Quote: Introduction: Chiari-like malformation (CM) and syringomyelia (SM) are frequently diagnosed conditions in small and toy dog breeds, such as the Cavalier King Charles Spaniel and Griffon Bruxellois. CM/SM is only rarely reported in Pomeranians in literature to date. The aims of this study are to 1/describe the phenotype of Pomeranians with or without CM/SM and 2/evaluate for differences and associations between CM/SM and owner-reported clinical signs (ORCS) or signalment factors. Materials and methods: From February 2015 to June 2023, historical data and signalment (including country of origin, pedigree, sex and neuter status, age, and body weight) and ORCS of Pomeranians were recorded at multiple institutions. MRI studies of all dogs were evaluated for classification of CM/SM. Additionally, quantitative measurements were performed for SM. Results: A total of 796 dogs from 22 different countries were included. Total prevalence of CM was 54.9% (437/796) and the prevalence of SM was 23.9% (190/796). The top 5 ORCS included 1/scratching with skin contact, rubbing head or ears, or both (57.6% of dogs with ORCS), 2/air licking (30.7% of dogs with ORCS), 3/spontaneous signs of pain (26.0% of dogs with ORCS), 4/persistent licking front and/or hind paws (22.6% of dogs with ORCS), 5/phantom scratching (22.6% of dogs with ORCS). Phantom scratching, vocalization, head shaking, spontaneous signs of pain, and air licking were associated with having SM. There were no statistically significant associations between quantitative syrinx measurements and ORCS. There were statistically significant associations between CM classification and 1/country of origin, 2/having a pedigree, and 3/age. There were statistically significant associations between SM classification and 1/age and 2/body weight. Discussion: This is the first large study evaluating CM/SM in the Pomeranian dog breed. Veterinary clinicians can use these findings to increase the likelihood of correctly determining the presence or absence of CM/SM in Pomeranians. Breeders may consider using the information regarding signalment factors as well as ORCS associated with CM/SM classifications to select dogs for screening procedures. But an MRI-based diagnosis is needed to properly ascertain the exact CM/SM status of their breeding stock until a fool-proof characteristic or genetic marker is found.

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2024

The effect of MRI-based screening and selection on the prevalence of syringomyelia in the Dutch and Danish Cavalier King Charles Spaniels. Citlalli Limpens, Vivian T. Smits, Hille Fieten, Paul Mandigers. Front. Vet. Sci. January 2024; doi: 10.3389/fvets.2024.1326621. Quote: Introduction: Syringomyelia (SM) is a heritable disorder causing a fluid filled cavity (FFC) in the spinal cord with a reported overall prevalence in the Cavalier King Charles Spaniels (CKCS) of 39 to 46%. Breeders started screening their CKCS with MRI in the Netherlands since 2004 and in Denmark since 2015. The goal of this study was to evaluate the effect of MRI-based selection in breeding on the prevalence of SM. Method: MRI scans of 2125 purebred CKCS were available. SM was defined as having a visible FFC in the spinal cord. Prevalence of SM per year of birth was calculated and a logistic regression was used to evaluate affected status of offspring from affected versus unaffected parents and age category of the parent. And to study the combined effect of parental status and age-category to evaluate the effect on affected status of the offspring. Results: The mean FFC in affected CKCS was 2.03 ± 1.47 mm and ranged from 0.5 to 9 mm (median of 1.5 mm). An age effect exists as older CKCS have a higher frequency of being affected compared to younger CKCS. There was no significant sex predilection for SM in this dataset. The mean prevalence of SM decreased slightly from 38% (2010-2014; 2.8 ± 1.3 years of age (mean ± sd); median 2.6 years) to 27% (2015-2019; 2.4 ± 1.2 years of age; median 2.1 years) in the screened population of CKCS (p= 4.3e-07). Breeding with 2 affected parents increased the Odds ratio for producing affected offspring with 3,08 (95% CI 1.58-6.04) compared to breeding with unaffected parents. Discussion: MRI-based screening and selection against SM led to a minimal decrease in prevalence of SM in the Dutch and Danish CKCS population. Breeding with dogs with SM significantly increases the risk of affected offspring. As the disorder is progressive with age, and based on the results of this study, MRI-based screening for all CKCS is recommended at an age of 3 years or older, and to reduce SM more effectively, CKCS affected with SM should not be used for breeding.

Clinical predictors of syringomyelia in Cavalier King Charles Spaniels with chiari-like malformation based on owners’ observations. Tenna Remler Pedersen, Maiken Bayer Thode Bach, Camilla Løkke Stougaard, Hanne Gredal, Clare Rusbridge, Nanna Brix Finnerup, Mette Berendt. Acta Vet. Scandin. February 2024; doi: 10.1186/s13028-024-00725-1. Quote: Background: Syringomyelia (SM) is a prevalent inherited developmental condition in Cavalier King Charles Spaniels (CKCSs) with Chiari-like malformation (CM), accompanied by a variety of clinical manifestations, including signs of neuropathic pain. Magnetic resonance imaging (MRI) is the gold standard in SM diagnosis. However, it is desirable to establish clinical predictors that can identify CKCSs with a large clinical syrinx that needs treatment, as some owners cannot afford or lack access to MRI. The aims of the study were to investigate owner-reported clinical signs of SM and clinical predictors of a large clinical syrinx, using predictive values of significant signs, individually and in combinations. Eighty-nine CKCSs participated in this retrospective study. Based on MRI diagnosis, dogs were distributed into three groups: CM without syrinx or with a maximum transverse width < 2 mm (n = 13), CM with small syrinx 2.00-3.99 mm (n = 26) and CM with large syrinx ≥4 mm (n = 50). A structured investigator-owner interview using a standardized questionnaire was used to collect data regarding clinical signs of CM and SM. The statistical tests Pearson’s chi-square, Fisher’s Exact and Spearman’s rank order were used to assess the difference in owner-reported signs between groups. For signs with significant differences, positive and negative predictive values (PPV and NPV) were calculated. Results: Following clinical signs were reported significantly more frequent in dogs with a large syrinx: phantom scratching, bilateral scratching of the neck or shoulder, aversion when that area is touched, or exacerbation of clinical signs when the dog is emotionally aroused. Each individual sign had a high PPV, indicative of a large clinical syrinx. The PPV increased further when the signs phantom scratching, aversion to touch to the head, neck or shoulder, and a preferred head posture during sleep were present in combination. Conclusions: Specific clinical signs can be used individually and in combination as clinical predictors of a large clinical syrinx in CKCSs with CM and SM. General practitioners can utilize this information to identify CKCSs with a large syrinx to initiate necessary treatment. This is particularly useful in cases where access to or affordability of an MRI diagnosis is limited.

Relationship between syringomyelia and myxomatous mitral valve disease in Cavalier King Charles spaniels. Maiken B. T. Bach, Camilla L. Stougaard, Maria S. Thøfner, Maria J. Reimann, Ulrik Westrup, Jørgen Koch, Merete Fredholm, Torben Martinussen, Mette Berendt, Lisbeth H. Olsen. J. Vet. Intern. Med. February 2024; doi: 10.1111/jvim.17018. Quote: Background: Syringomyelia (SM) and myxomatous mitral valve disease (MMVD) are highly prevalent in Cavalier King Charles spaniels (CKCS). Cardiac status in CKCS with and without SM is currently unknown. Objectives: To investigate the association between SM and MMVD severity in CKCS and CKCS with SM with and without clinical signs of SM. Animals: . ... The study cohort consisted of 55 CKCS, 40 CKCS with SM and 15 CKCS without SM that had Magnetic Resonance Imaging (MRI) at the University [of Copenhagen, Denmark] Hospital for Companion Animals, Department of Veterinary Clinical Sciences in 2007-2015. ... Over the years, national breeding schemes have been established to reduce the occurrence of MMVD in CKCS, reducing the prevalence of early onset heart murmur in CKCS. At the same time, however, no such breeding restrictions have been established to remove CKCS with early-onset SM from the breeding program, thereby reducing the incidence of SM. The concern that longstanding MMVD-breeding restrictions could potentially influence the prevalence of SM, motivated the present study. Therefore, this study aimed to investigate MMVD in CKCS with and without SM. The secondary aim of this study was to investigate the severity of MMVD in SM affected CKCS with and without clinical signs of SM. ... Methods: A combined retrospective and prospective study. MRI and echocardiography were used to diagnose SM and MMVD, respectively. The association between SM and MMVD severity (left ventricle internal diameter in diastole normalized to bodyweight [LVIDDN] and left atrium to aortic ratio [LA/Ao]) were tested using multivariable linear regression analysis adjusting for sex and age. ... Based on American College of Veterinary Internal Medicine (ACVIM) consensus statement guidelines, the severity of MMVD was staged as follows: Group A, CKCS with no auscultatory heart murmur and normal echocardiogram (no or minimal MR [MR<20%]); group B1, CKCS with an auscultatory heart murmur or MR ≥20% and echocardiographic evidence of MMVD but no cardiac enlargement (LA/Ao<1.6 and LVIDDN<1.7); group B2, CKCS with heart murmur ≥3 of 6 and current or previous echocardiographic evidence of cardiac enlargement (LA/Ao≥1.6 and LVIDDN≥1.7), but without current or previous clinical signs of CHF; group C, CKCS with CHF. Congestive heart failure was defined as a history of MMVD, clinical signs of CHF (eg, cough, dyspnea, tachypnea, nocturnal restlessness, and exercise intolerance), echocardiographic changes compatible with CHF caused by MMVD and response to diuretic treatment. ... In total, 32 of the 55 CKCS were diagnosed with ACVIM MMVD stage B1, 7 with stage B2 and 3 dogs with stage C. ... Results: Overall, no significant difference in LVIDDN and LA/Ao was found between CKCS with or without SM. However, CKCS with symptomatic SM had significantly smaller LVIDDN (1.45 [1.30-1.50]) (median [IQR]) and LA/Ao (1.20 [1.10-1.28]) compared to CKCS with asymptomatic SM (1.60 [1.50-1.90] and 1.40 [1.20-1.75]) as well as CKCS without SM (0.24 [0.03-0.45] and 0.30 [0.05-0.56]) (all P values <.03). Conclusions and Clinical Importance: ... This study investigates the co-occurrence of SM and MMVD. We found no overall association between SM (symptomatic and asymptomatic pooled together) and the severity of MMVD in CKCS, but CKCS with symptomatic SM exhibited smaller left ventricular and left atrial dimensions compared to those with asymptomatic SM and CKCS without SM, suggesting that a complex relationship might exist. However, this study was limited by a relatively small and selected study sample.

Cerebrospinal Fluid Concentrations of Calcitonin Gene Related Peptide in Dogs with Chiari-Like Malformation. John Macri; Natasha Olby; Courtney Whicker. ACVIM Forum 2024. June 2024. Quote: Background: Cavalier King Charles Spaniels (CKCS) have a high prevalence of Chiari-like malformation and syringomyelia (CMSM). Dogs with CMSM display signs of neuropathic pain and itch. Imaging findings often do not correlate with severity of signs. Neuropeptides including calcitonin gene related peptide (CGRP) have been implicated in neuropathic pain. Hypothesis: Cerebrospinal fluid (CSF) concentrations of CGRP (C-CGRP) will correlate with CMSM clinical sign severity. Animals:S Twenty-nine CKCS. Methods: CKCS underwent pain and itch quantification by owners (questionnaires) and investigators (physical examination), a brain and cervical spine MRI, and lumbar CSF collection. CSF was frozen to -80°F. C-CGRP in CSF were measured using an ELISA assay (MyBiosource, San Diego, CA). Dogs were grouped by presence of syrinx, pain, and itch, and C-CGRP were compared between groups using Wilcoxon Rank Sum; C-CGRP and owner reported pain score were evaluated using linear regression analysis. Results: 15/29 CKCS had SM on MRI, 13/29 were painful, and 12/29 were scratching. C-CGRP was significantly higher in painful dogs (median 114.3, range 11.6–238.3 pg/ml) and dogs with itch (111.67, 38.5–234.8 pg/ml) compared to non-painful dogs (72.57pg/ml, 0–266.2 pg/ml) (p=0.025) and dogs without itch (79.7, 0–266.2 pg/ml). There was a significant correlation between owner pain score and C-CGRP (R2=18%, p=0.033). No significant difference in C-CGRP was noted between SM+ (99, 0–226.6 pg/ml) and SM- (102.2, 5.9–266.2 pg/ml) dogs (p=0.25). Cconclusions: CSF CGRP concentration is elevated in CKCS exhibiting pain and itch. CGRP may contribute to neuropathic pain in CMSM and could be a target for therapeutic intervention.

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