Corneal Ulcers and the
Cavalier King Charles Spaniel


Some cavalier King Charles spaniels may develop deep abrasions -- ulcers -- in the corneas of their eyes, as a result of their short muzzles and head shapes. Such brachycephalic dogs, including the CKCS, may also be predisposed to ulcers of their corneas, due their apparent "bulging" eye balls (called "macropalpebral fissures") and cases of  inability to blink fully ("lagophthalamos"), which make them vulnerable to scratches and infections. Untreated dry eye conditions also can lead to ulceration.

Untreated cases of corneal ulceration can cause more severe conditions, including "corneal melting" which presents a high risk of permanent blindness. See this September 2014 study.


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What It Is

The cornea is the transparent membrane outer surface of the eyeball, and is a smooth, moist, and usually transparent structure when healthy. It consists of three layers: the outer layer is called the epithelium; beneath it is the stroma; and the deepest layer is Descemet's membrane. Corneal ulceration is the loss of a portion of the outer or more layers of the cornea.  Corneal ulceration is one of the most common eye diseases in domestic dogs, and is a major cause of blindness due to either scarring or corneal perforation. Damage to the Corneal ulcer due to dry eye conditioncornea can cause substantial pain. Corneal ulcers vary in severity, and can be classified into grades based on their depth. More superficial lesions tend to be more painful as the nerve endings within the cornea are close to the surface.

Corneal ulcers may be caused by a direct injury, tear abnormalities such as dry eye, external irritants, eyelid or eyelash abnormalities such as distichiasis or entropion, immune-mediated or allergic inflammation, foreign bodies, or the inability to blink. The photo at right is of the eye of a cavalier with an ulcer -- the greenish area -- just above the white mark in the upper left of the eyeball, which resulted from an untreated dry eye condition (Photo by Dr. Christine Heinrich).

 

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Symptoms

Corneal ulceration causes extreme pain, redness, light sensitivity, watering eyes, and twitching eyelids. The ulcer may also be visible to the naked eye when examined closely.

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Diagnosis

Fluorescein stainingCorneal ulcers are detected by applying a stain, such as fluorescein. Fluorescein is a water-soluble stain applied to the cornea to detect corneal ulcers. Either sterile fluorescein strips or sterile vials of fluorescein dye  are used to stain the cornea. An ulcer in the epithelial surface appears bright green (see photo at right), especially under an ultraviolet or cobalt blue light.  If the ulcer very deep, a sample may be taken for a culture and cell study before applying the stain or medication.

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Elizabethan CollarTreatment

Medication includes antibiotic drops or ointment to prevent bacterial infections*, and atropine drops or ointment to relieve the pain. The pain medication must be applied daily, and the antibiotic even more frequently. The injured eye must be protected during the healing process, so usually the dog will be required to wear a cone -- Elizabethan collar -- attached around its neck.

* In a September 2015 article, researchers report that a cavalier with a corneal ulcer but no history of trauma had developed a fungal organism which was treated with antifungal treatment, including 1% voriconazole solution or 1% itraconazole ointment.

Usually after a week to ten days, the eye is re-examined to determine if it has healed, again using the fluoresein stain. If healing is not progressing normally, or if a complication develops, your veterinarian will recommend additional medical treatment or surgery.

In a November 2016 article, French and UK ophthalmologists reported the 100% successful use of pig bladder grafts for corneal reconstruction in 27 dogs (and three cats), including two cavalier King Charles spaniels suffering from deep melting corneal ulcers. After 90 days following surgery, all eyes were sighted. They concluded that "Use of a porcine urinary bladder acellular matrix appears to be effective in the surgical management of deep corneal ulcers and feline corneal sequestra."

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What You Can Do

Craniofacial RatioIn a May 2015 report, UK researchers found that cavaliers were among the breeds most commonly affected by corneal ulcers. They calculated a measurement called the craniofacial ratio (CFR), which was the muzzle length (A - B in the photo at right) divided by the cranial length (C - D). They determined that brachycephalic dogs (including the pug, Shih Tzu, bulldog, as well as the cavalier), had a craniofacial ratio of <0.5 and were twenty times more likely to be affected than non-brachycephalic dogs (The cavalier in the photo has a craniofacial ratio of 0.27.)  In addition, they found that: (a) a 10% increase in relative eyelid aperture width more than tripled the ulcer risk, and (b) exposed eye-white was associated with a nearly three times increased risk. They concluded that:

"The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare."
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Research News

Dr. Olivier BallandNovember 2016: Pig bladder grafts successfully return sight to two cavaliers with corneal ulcers. In a November 2016 article, French and UK ophthalmologists (Olivier Balland [right], Anne-Sophie Poinsard, Frank Famose, Frédéric Goulle, Pierre-François Isard, Iona Mathieson, Thomas Dulaurent) report the 100% successful use of pig bladder grafts for corneal reconstruction in 27 dogs (and three cats), including two cavalier King Charles spaniels suffering from deep melting corneal ulcers. After 90 days following surgery, all eyes were sighted. They concluded that "Use of a porcine urinary bladder acellular matrix appears to be effective in the surgical management of deep corneal ulcers and feline corneal sequestra."

August 2015: UK researchers opine that corneal ulcers in cavaliers may be due to the breed standard favoring large eyes. In a May 2015 study by a team of researchers (Rowena M. A. Packer, Anke Hendricks, Charlotte C. Burn) from the UK's Royal Veterinary College, they measured eleven conformational features demonstrated to be breed-defining (muzzle length, cranial length, head width, eye width, neck length, neck girth, chest girth, chest width, body length, height at the withers and height at the base of tail) of 700 dogs, 31 dogs of which were affected with corneal ulcers, including three cavalier King Charles spaniels. They specifically criticized the CKCS breed standard for considering "large" eyes as a desirable feature, and also noted that the cavalier's predisposition to dry eye can lead to corneal ulcers. They stated:

"Several brachycephalic breeds have been identified as being predisposed to dry eye, including the Bulldog, Lhasa Apso, Shih Tzu, Pug, Pekingese, Boston Terrier and Cavalier King Charles Spaniel. Even moderately lowered tear production associated with dry eye may produce clinical signs in brachycephalic dogs, as a larger portion of the globe is exposed. In a UK based study, a higher proportion of brachycephalic dogs that were affected by dry eye were also affected by ulcers, than were non-brachycephalic dogs with dry eye, e.g. 36% of Shih Tzus and 30% of Cavalier King Charles Spaniels versus 17% of dogs in the overall study population."

They devised morphometric predictors for corneal ulcers, including the "craniofacial ratio" (CFR), "the Cavalier King Charles Spaniel has a craniofacial ratio of 0.27muzzle length divided by the cranial length, which quantifies the degree of brachycephaly", to differentiate skull morphologies. [Photos at right: "This Cavalier King Charles Spaniel has a craniofacial ratio of 0.27 (muzzle length 28mm / cranial length 102mm), and a relative palpebral fissure width value of 33.3% ((palpebral fissure width 34mm / cranial length 102mm) *100".]

 They found that brachycephalic dogs (craniofacial ratio <0.5) were twenty times more likely to have corneal ulcers than non-brachycephalic dogs. In addition, they found that: (a) a 10% increase in relative eyelid aperture width more than tripled the ulcer risk, and (b) exposed eye-white was associated with a nearly three times increased risk. They concluded that:

"The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare."
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Related Links

Veterinary Resources

Evaluation of accelerated collagen cross-linking for the treatment of melting keratitis in eight dogs. Frank Famose. Vet. Ophth. September 2014;17(5):358-367. Quote: Objective: Melting keratitis is serious condition presenting a high risk of permanent blindness and is caused by infectious or noninfectious factors. In humans, the clinical efficacy of collagen cross-linking (CXL) has been described in the treatment of refractory infectious keratitis by arresting keratomalacia. The aim of this study was to evaluate the efficacy of accelerated CXL for the treatment of melting keratitis in dogs. Animal studied and Procedure: Eight dogs ... two were Cavalier King Charles Spaniels with macropalpebral fissures ... were treated for unilateral melting keratitis by accelerated CXL. Corneas were irradiated by UVA (370 nm) at 30 mW/cm² irradiance for 3 min after soaking by 0.1% riboflavin in 20% dextran for 30 min. Follow-up was conducted 3, 7, 14, and 30 days after treatment. Results: Pain improvement was observed for all cases within 3 days after treatment. Epithelial healing was observed within 15 days for all cases. Disappearance of cellular infiltration was observed for all cases at day 7. The corneal vascularization disappeared for 4 of 8 dogs and was reduced for 4 of 8 dogs within 1 month. At 1 month, all cases presented a variable degree of corneal scarring, but all eyes had visual function. ... In the present study, at 30 days after the treatment, corneal melanosis was observed in 3 of 5 brachycephalic dogs, but not in the two Cavalier King Charles Spaniels that presented with macropalpebral fissures nor in the Great Dane with euryblepharon. ... No recurrent infection was observed. Conclusions: The main observation of this study is that all the cases have presented with the same clinical result regardless of the presence and the sensitivity of the infectious agents and regardless of the duration of the condition prior to CXL treatment. Accelerated CXL appears to be a valuable option for the treatment of melting keratitis.

Advances in treating ocular issues. Christine Heinrich. Vet. Times. November 24, 2014:8-12. Quote: "Canine dry eye is a painful and blinding disease, which, unfortunately, is not usually successfully managed with only the use of tear replacements – even if the client has the time and inclination to comply with complex treatment schedules. In the past, it must have been disheartening – even with frequent applications of tear replacements – for colleagues to watch patients with severe dry eye continuing to suffer from excessive amounts of tenacious ocular discharge, progressive corneal pigmentation, vision loss and, at times, devastating corneal ulceration."

Ocular alkaline injury in four dogs – presentation, treatment, and follow-up – a case series. Claudia Busse, Claudia Hartley, Cristiane Kafarnik, Mauro Pivetta. Vet.Ophth. March 2015;18(2):127-134. Quote: Purpose: To describe presentation, treatment, and follow-up after unilateral alkaline injuries to the eye in four dogs. Material and method: The case notes of four patients that suffered from alkaline injuries to the eye were included in this series. Results: Acute clinical signs included blepharospasm and edema of the eyelids, chemosis and conjunctival hyperemia, conjunctival ischemia, destruction of the corneal epithelium, a whitish haze of the corneal stroma, mild corneal edema, and uveitis. Two patients showed depigmentation of the eyelids. Presumed endothelial cell damage resulted in severe corneal edema in two dogs. Long-term complications included phthisis bulbi, scarring of the eyelids and damage to the meibomian glands, symblepharon formation, conjunctivalization of the cornea, corneal vascularization, pigmentation, and fibrosis. Persisting corneal edema was seen in the dogs with presumed endothelial Figure 1cell damage. One dog developed a mild bullous keratopathy with superficial corneal ulcerations 4½ years after the injury and had a reduced anterior chamber depth on ultrasound. Conclusion: The damage to the ocular structures described here mainly affects the ocular surface. One patient presumably suffered an injury to the ciliary body epithelium resulting in a phthisical globe. Chronic corneal edema, conjunctivalization, and scarring can result in permanent visual impairment. Healing of the ocular surface can take weeks and is associated with a dramatic vascular response. However, a severely vascularized cornea has the potential to clear and allow a good visual outcome long term. Ongoing discomfort was only seen in one case with persistent corneal edema and a secondary bullous keratopathy. ... Case 1: A 4-week-old cavalier King Charles spaniel was presented to the Animal Health Trust (AHT) after her right eye was exposed to caustic soda (sodium hydroxide). The eye was flushed by the owner with tap water. The referring veterinarian (RV) treated the dog with the following medications: systemic meloxicam, buprenorphine, amoxicillin and clavulanic acid, topical tetracaine eye drops, and artificial tears. An ophthalmic examination at the AHT 12 h after the injury revealed mild blepharospasm and mucoid discharge in the right eye, with moderate chemosis and conjunctival hyperemia. The dorsolateral aspect of the right cornea showed a superficial ulceration and a whitish haze in the stroma and mild corneal edema (Fig. 1 -- above left). Figure 2There was no aqueous flare, but the right pupil was slightly miotic relative to the left. Menace response, dazzle reflex, and the consensual pupillary light reflex from right to left were present. The pH of the lower conjunctival sac was assessed using a Combur-Test urine test strip (Roche, Mannheim, Germany) and was pH7 and therefore within normal limits. The remainder of the ophthalmic examination was within normal limits. Intraocular pressure measurements were not documented. The dog was admitted to the hospital for intensive medical treatment. The dog was discharged after 2 days as the corneal ulcer was starting to epithelialize. At reexamination 7 days after the initial presentation, corneal vascularization was present from the dorsal limbus and 90% of the corneal ulcer was re-epithelialized. Three weeks after the injury, the cornea was fluorescein negative with vascularization extending over the entire affected area. A reexamination 4 months after the trauma revealed only mild perilimbal pigmentation in the dorsal quadrant of the right cornea (Fig. 2 -- at right).

Impact of Facial Conformation on Canine Health: Corneal Ulceration. Rowena M. A. Packer, Anke Hendricks, Charlotte C. Burn. PlosOne. May 2015. Quote: "Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. ... Several brachycephalic breeds have been identified as being predisposed to dry eye, including the Bulldog, Lhasa Apso, Shih Tzu, Pug, Pekingese, Boston Terrier and Cavalier King Charles Spaniel. Even moderately lowered tear production associated with dry eye may produce clinical signs in brachycephalic dogs, as a larger portion of the globe is exposed. In a UK based study, a higher proportion of brachycephalic dogs that were affected by ulcers, than were non-brachycephalic dogs with dry eye, e.g. 36% of Shih Tzus and 30% of Cavalier King Charles Spaniels versus 17% of dogs in the overall study population.  ... This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled) skull shape, the presence of a nasal fold (wrinkle), and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not), or if a previous diagnosis of corneal ulcer(s) was documented in the dogs’ histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%), small breed dogs (mean± SE weight: 11.4±1.1 kg), the most common being the Pug (n = 12 affected), the Shih Tzu (n = 4), the Bulldog and the Cavalier King Charles Spaniel (n = 3). ... Morphometric data were collected for each dog using previously defined measuring protocols, measuring 11 conformational features that were demonstrated to be breed-defining: muzzle length, cranial length, head width, eye width, neck length, neck girth, chest girth, chest width, body length, height at the withers and height at the base of tail (all in cm). ... A further morphometric predictor of interest for corneal ulcers was craniofacial ratio, (CFR): the muzzle length divided by the cranial length, which quantifies the degree of brachycephaly, was used to differentiate skull morphologies. [Photos at right: "This Cavalier King Charles Cavalier King Charles Spaniel has a craniofacial ratio of 0.27Spaniel has a craniofacial ratio of 0.27 (muzzle length 28mm / cranial length 102mm), and a relative palpebral fissure width value of 33.3% ((palpebral fissure width 34mm / cranial length 102mm) *100"]  ... [B]rachycephalic dogs (craniofacial ratio <0.5) were twenty times more likely to be affected than non-brachycephalic dogs. A 10% increase in relative eyelid aperture width more than tripled the ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare."

Key Points in Complicated Canine Corneal Ulcers. Diane Hendrix, Georgina Newbold. Vet. Brief. September 2015. Quote: Complicated corneal ulcers are epithelial defects that remain unresolved after several days, become infected, or show progressive deepening into the stroma. Complete ocular examination—including a Schirmer’s tear test and a light examination of the eyelids and conjunctiva—may or may not reveal the underlying cause. Recognizing a complicated ulcer is critical for appropriate management of these potentially vision-threatening keratopathies. Clinical Findings: An ulcer is considered complicated based in part on its depth and duration. Even without a detailed history, the cornea offers clues during the course of the disease. Corneal vessels generally appear at the limbus after 7-10 days, then grow approximately 1 mm per day, so corneal vascularization is a sign of chronicity. Etiologies: An ulcer generally becomes complicated because of infection, indolence (ie, failure of the epithelium to adhere to the underlying stroma), or lack of treatment for the primary cause.

Outcome of phacoemulsification following corneal and lens laceration in cats and dogs (2000–2010). Barbara K. Braus, Alexander Tichy, Heidi J. Featherstone, Peter W. Renwick, Michael Rhodes, Christine L. Heinrich. Vet. Ophthalmology. December 2015. Quote: "Objective: To investigate the success rate of phacoemulsification following corneal and lens laceration in dogs and cats. Procedure: Retrospective review of cats and dogs presenting with corneal and lens laceration and treated with phacoemulsification. Results: The records of 33 patients (33 eyes: six feline, 27 canine) presenting to a private referral center were reviewed. ... Dogs: English Springer Spaniels (7/27; 25.9%), Crossbreeds (4/27; 14.8%), and Cavalier King Charles spaniels (3/27; 11.1%) were most commonly affected by corneal and lens laceration. ... Affected dogs were younger (median 18 months) than affected cats (median 30 months). The lacerations were caused by cat scratch trauma (9/33), thorn injury (6/33), and glass shards (1/33); the cause was unknown in 17/33 cases. All cats and 85.2% of all dogs were visual at the last examination. The median follow-up was 4 and 8 months for cats and dogs, respectively. In all canine cases that developed vision loss, this occurred within the first 14 weeks postoperatively. The ultimate cause for vision loss in dogs was secondary glaucoma (4/4) and retinal detachment (1/4). Conclusion: Cats have an excellent outcome and dogs a very good outcome following surgery for corneal and lens laceration. The cause of the trauma, the size of the lesion, the time interval between the ocular trauma and surgery, and the type of surgery were not found to have an influence on the outcome of patients in this study. We postulate that vision loss might develop more often in cases with complications associated with the initial corneal laceration wound."

Keratomycosis in five dogs. Jessica C. Nevile, Simon D. Hurn, Andrew G. Turner. Vet. Ophthalmology. September 2016;19(5):432-438. Quote: "Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. ... Case 1. A 10-year 7-month-old spayed female Cavalier King Charles Spaniel was referred for a corneal ulcer in the right eye (OD). The dog was systemically healthy, there was no known history of trauma, and the dog had not been treated with topical or systemic corticosteroids prior to presentation. ... Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients."

Use of a porcine urinary bladder acellular matrix for corneal reconstruction in dogs and cats. Olivier Balland, Anne-Sophie Poinsard, Frank Famose, Frédéric Goulle, Pierre-François Isard, Iona Mathieson, Thomas Dulaurent. Vet. Ophthal. November 2016;19(6):454-463. Quote: Objective: To describe the use of a porcine urinary bladder acellular matrix for surgical reconstruction of the cornea in cases of canine and feline deep corneal ulcers, and feline corneal sequestra. Materials and methods: Twenty-seven dogs [including two cavalier King Charles spaniels] and three cats with deep corneal ulcers and seven cats with corneal sequestra were included in the study with overall 38 eyes. [Both CKCSs had deep melting corneal ulcers.] For each patient, the necrotic material (ie corneal sequestrum or collagenolytic tissue) was removed by circular lamellar keratectomy. The collagen graft was then cut and prepared to match the stromal defect and then sutured into the lamellar keratectomy bed using interrupted and continuous patterns of absorbable polyglactin 9–0 sutures. Postoperative medical treatment consisted of topical and systemic administration of antibiotics, combined with topical administration of atropine sulfate. The animals were examined 18, 45, and 90 days after the surgery. Results: Postoperative examination revealed complete integration of the biomaterial in 93.5% of ulceration cases in both species and in 100% of feline corneal sequestrum cases. In two cases of ulceration (1 dog and 1 cat), progression of the collagenolytic process at the graft periphery required an additional conjunctival graft 7 days after the first surgery. At 90 days post-op, 100% of the eyes were sighted. Conclusion: Use of a porcine urinary bladder acellular matrix appears to be effective in the surgical management of deep corneal ulcers and feline corneal sequestra.

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