Dry Eye Syndrome and the Cavalier King Charles Spaniel

Dry Eye Syndrome:

A Life-Long Irritating Defect For Cavaliers

Many Cavalier King Charles Spaniels suffer from a painful genetic disorder called dry eye syndrome (keratitis sicca or keratoconjunctivitis sicca -- KCS). Dry eye is an inflammation of the cornea and conjunctiva due to an inability to produce watery tears, and it cannot be cured in Cavaliers.

Dry eye prevents the Cavalier's eyes from being properly moistened, resulting in chronically dry, burning eyes, and scarring and painful ulceration of the cornea which may lead to decreased vision. The disorder requires frequent medication every day.

All CKCSs should be examined at least annually by a board certified veterinary ophthalmologist. They are listed on this webpage of the website of the American College of Veterinary Ophthalmologists (ACVO): www.acvo.org/ locate.htm

Symptoms

In the Cavalier King Charles Spaniel, the most common cause of dry eye syndrome is an immune-mediated destruction of the tear glands. Initial symptoms include chronic redness of the eye, chronic thick, yellow-green discharge, especially in the morning, and the development of a film over the cornea.

Treatment

Early treatment of dry eye is crucial to preventing destruction of the CKCS's cornea. Treatment is aimed at increasing tear production, applying artificial tears, and reducing any bacterial infections, and decreasing inflammation and scarring of the cornea. The dog's eyes must be kept clean and free of discharge. The patient may be treated initially with a topical antibiotic or anti-inflammatory. Medications such as cyclosporine ophthalmic emulsion (Restasis) and tacrolimus ophthalmic suspension are commonly prescribed daily for life to increase tear production, and artificial tear solutions must be applied frequently each day to eliminate bacteria, rinse the eyes, and remove discharge. Another frequently prescribed product to help relieve discomfort, itching, and burning is sodium hyaluronate (Hy-Optic by Kinetic Technologies).

Surgery rarely is a successful option. In severe cases that do not respond to medications, an expensive surgical procedure may be performed in which a salivary duct is moved from the mouth to the eye. This results in saliva flowing over the eye to keep the eye moist. It is not an ideal treatment for dry eye, because saliva is not the same as tears, and the flow of saliva cannot be as well controlled. The surgery is helpful, however, for those dogs that remain persistently painful and squinty despite trying all forms of medical therapy.

Curly Coat -- Rough Coat Syndrome in Cavalier King Charles Spaniels

A rarer but far more severe form of dry eye syndrome in some Cavalier puppies is a combination of dry eye and a congenital skin condition called "curly coat" or "rough coat" syndrome (ichthyosis keratoconjunctivitis sicca). The reference to a curly or rough coat comes from the unusually curly abnormality of the Cavalier's coat which is apparent at birth. However, the puppy also suffers from an extreme version of dry eye, and as the affected dog matures, it develops a deterioration of the skin which results in seborrhea, consisting of skin inflammation and excessive oiliness. Also, the dog's teeth, gums, and other connective tissues may be adversely affected. The form of dry eye associated with curly coat also is rare in that it is of congenital origin.

In cases of curly coat (rough coat) syndrome, nearly continuous daily care, including very frequent medicinal bathing, is required to treat the skin condition, as well as applying the eye medications. In a 2003 study reported by Dr. Keith C. Barnett, OBE MA PhD BSc DVOphthal FRCVS DIpECVO, European Specialist in Veterinary Ophthalmology, the dry eye condition of curly coat dogs may be so severe that cyclosporine therapy is ineffective, and the skin condition progresses into severe lesions. In a September 2006 paper, Dr. Barnett reported that successful treatment of the skin condition is not possible, although there can be some improvement in the dry eye condition.

Dr. Barnett reported that the need for constant care of the eyes and skin may lead breeders to resort to early euthanasia of the affected puppies as the only humane result, to avoid the dogs suffering from lifetimes of extreme discomfort and permanent eye damage.

No cases of the combination of dry eye syndrome and curly coat syndrome have been reported in any other breed. Studies have been conducted in the United States, United Kingdom, Australia, Sweden, the Czech Republic, and Iceland. It is believed to be due to a simple autosomal recessive gene. If so, then affected puppies are more likely to be found in cases of line breeding or inbreeding on carrier bloodlines. During a two year period recently in Iceland, more than half of many litters of Cavalier puppies were born affected by the syndrome. The disorder may be more widespread than previously believed as more owners and veterinarians become aware of its symptoms.

See Current Research below for more information about this syndrome.

Breeders' Responsibilities

The Canine Inherited Disorders Database recommends that dogs affected with dry eye not be bred. Since dry eye is an hereditary disease in Cavaliers, breeders also should never breed any CKCS which has parents or grandparents which have had dry eye. Dry eye in any littermates of breeding stock should be taken into consideration. All Cavalier breeding stock should be examined by board certified veterinary ophthalmologists at least annually and cleared by the veterinary specialists for dry eye, the closer the examination to the breeding the better.

4The Animal Health Trust (AHT) is conducting research to try to establish the pattern of inheritance of CKCS puppies born with the combination of both dry eye and curly coat syndrome (ichthyosis keratoconjunctivitis sicca), which appears to be unique to the Cavalier as a breed. According to Dr. Keith C. Barnett, OBE MA PhD BSc DVOphthal FRCVS DIpECVO, European Specialist in Veterinary Ophthalmology, who has been studying these conditions for several years, no cases of the two abnormalities occurring together have been recorded in any other breed.

Dr. Barnett and Dr. Cathryn Mellersh, BSc(hons) PhD, senior canine geneticist at the AHT, are leading a team of AHT colleagues who are researching the DNA of the puppies. Dr. Mellersh reports that twenty-seven candidate genes have been identified and the tests are currently in progress and final results are pending.

Dr. Barnett requests that breeders who have puppies affected with these combined disorders send blood samples and skin tissue samples from the affected puppies, their siblings, and parents to identify the responsible gene. Contact Dr. Barnett at the AHT if you wish to participate in the research project. He may be reached at Animal Health Trust, Lanwades Park, Kentford, Newmarket, CB8 7UU, United Kingdom; telephone: (+44) (0)8700 502424; email: Keith.Barnett@aht.org.uk Blood samples of 3 to 5 ml should be provided in ETDA anti-coagulant tubes. Alternatively, for very young or old donors, cheek swabs may be used. Samples should be marked for the attention of Dr. K. Barnett and sent to: Sarah Gray, The Animal Health Trust, Lanwades Park, Newmarket Suffolk CB8 7UU UK. Please indicate clearly that the samples are Curly Coat affected or related. Dr. Mellersh may be reached at Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, United Kingdom; telephone: (+44) (0)1638 750659 ; email: cathryn.mellersh@aht.org.uk

4Drs. R. F. Sanchez (England), G. Innocent (Scotland), J. Mould (England), and F. M. Billson (Australia) reported in their January 2007 article, Canine keratoconjunctivitis sicca: disease trends in a review of 229 cases, in the Journal of Small Animal Practice, Volume 48, that the Cavalier King Charles spaniels in their study "showed a more acute disease pattern with a biphasic age distribution at 0 to less than two years of age, and four to less than six and six to less than eight years of age, respectively, with more males affected than females and a significantly higher incidence of ulcerative keratitis in some cases resulting in corneal perforation."

Control of Canine Genetic Diseases, Padgett, G.A., Howell Book House 1998, pp. 198-199, 240.

Dry eye and curly coat in the Cavalier King Charles Spaniel, Barnett, KC, Veterinary Ophthalmology 6 (4), 343-350, Dec. 2003.

Guide to Congenital and Heritable Disorders in Dogs, Dodds WJ, Hall S, Inks K, A.V.A.R., Jan 2004, Section II(179).

Breed Predispositions to Disease in Dogs & Cats, Alex Gough, Alison Thomas. 2004; Blackwell Publ. 44-45.

Congenital keratoconjunctivitis sicca and ichthyosiform dermatosis in the cavalier King Charles spaniel. K. C. Barnett. J.Sm.Anim.Prac. 2006 Sep;47(9):524-8. Quote: "Objectives: To record a previously unreported congenital and hereditary condition affecting the eyes and skin in the cavalier King Charles spaniel. ... In the cavalier King Charles spaniel, the coat abnormality was noted at birth by the breeders as a 'curly coat', with deterioration of the skin signs as the animal became adult."

Canine keratoconjunctivitis sicca: disease trends in a review of 229 cases. R. F Sanchez, G Innocent, J Mould, F. M Billson. Journal of Small Animal Practice, vol.48; 2007. Quote: "There were 44 breeds in the study, with four breeds, English cocker spaniels, cavalier King Charles spaniels, West Highland white terriers and shih-tzus, making up 58 per cent of the cases. ... In contrast, cavalier King Charles spaniels and shih-tzus showed a more acute disease pattern with a biphasic age distribution at 0 to less than two years of age, and four to less than six and six to less than eight years of age, respectively, with more males affected than females and a significantly higher incidence of ulcerative keratitis in some cases resulting in corneal perforation. ... In the USA, predisposed breeds include cavalier King Charles spaniels (CKCS), English bulldogs, Lhasa apsos, shih-tzus, West Highland white terriers (WHWT), pugs, bloodhounds, American cocker spaniels, Pekingeses, Boston terriers, miniature schnauzers and Samoyeds (Kaswan and Salisbury 1990)."

Canine Inherited Disorders Database: http://www.upei.ca/~cidd/Diseases/ocular%20disorders/keratoconjunctivitis%20sicca%20.htm