Genetic Eye Disorders in
Cavalier King Charles Spaniels
The cavalier King Charles spaniel has more than its fair share of severe genetic diseases afflicting the eye. A 1999 study of cavaliers conducted by the Canine Eye Registration Foundation showed that an average of 30% of all CKCSs evaluated had eye problems.
They include hereditary cataracts, corneal dystrophy, distichiasis, dry eye syndrome, entropion, microphthalmia, progressive retinal degeneration, and retinal dysplasia, all of which are discussed on this website. Other hereditary eye disorders, of more minor nature, are not discussed.
Some cavaliers may develop other eye disorders which are considered genetic in other breeds. These include "prolapsed gland of nictitans", also known as "cherry eye". The nictitating membrane is the dog's third eyelid, a small triangular flap of cartilage in the inner corner of the eye, which covers a tear gland. Breeds predisposed to cherry eye include the Beagle, Boston terrier, bulldogs, Cocker spaniel, and Lhasa Apso. include the Beagle, Boston terrier, bulldogs, Cocker spaniel, and Lhasa Apso.
If and when the gland should flip upward (prolapses), it becomes inflamed and protrudes and bulges over the third eyelid, giving the appearance of a reddish cherry. (See a CKSC's eye with cherry eye, at left.) While the appearance of cherry eye is disturbing, it usually is not painful to the dog. Nevertheless, cherry eye should be treated promptly, because it may lead to chronic irritation of the cornea, conjunctiva, and dry eye (keratoconjunctivitis sicca or KCS).
Cherry eye usually requires some surgical treatment. In some mild instances, the ophthalmologist may be able to relocate the gland into its proper position without surgery. Replacing the gland is almost always necessary. Unfortunately, a high percentage of gland-replacement surgeries result in the loss of the gland’s tear-producing ability, causing dry eye.
In many instances, the eye disorders CKCSs experience may be attributed to the brachycephalic shape of their heads. All cavaliers 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.
Blindness: A Step-by-Step Approach to Diagnosis. Alison Clode. NAVC Clinician's Brief. April 2014;14-15.
The genetics of eye disorders in the dog. Cathryn S. Mellersh. Canine Genetics & Epidemiology. April 2014. Quote: "Inherited forms of eye disease are arguably the best described and best characterized of all inherited diseases in the dog, at both the clinical and molecular level and at the time of writing 29 different mutations have been documented in the scientific literature that are associated with an inherited ocular disorder in the dog. The dog has already played an important role in the identification of genes that are important for ocular development and function as well as emerging therapies for inherited blindness in humans. Similarities in disease phenotype and eye structure and function between dog and man, together with the increasingly sophisticated genetic tools that are available for the dog, mean that the dog is likely to play an ever increasing role in both our understanding of the normal functioning of the eye and in our ability to treat inherited eye disorders. This review summarises the mutations that have been associated with inherited eye disorders in the dog."