Corneal Dystrophy and the
Cavalier King Charles Spaniel
Corneal dystrophy is a genetic disorder which is relatively common in cavalier King Charles spaniels. It is the development of gray-white opaque deposits of calcium and fats under the surface of both of the dog's corneas. They usually appear in cavaliers between the ages of two and four years.
The form of corneal dystrophy most common among CKCSs is epithelial/stromal dystrophy, which describe the gray-white opacity which is visible in the dog's eyes. (See photo below at right.)
All CKCSs should be examined at least annually by a board certified veterinary ophthalmologist. They are listed on the website of the American College of Veterinary Ophthalmologists (ACVO).
Corneal dystrophy usually does not affect vision, is not painful, and no treatment is necessary. In an abstract presented to the 2010 WSAVA Congress by Dr. Charlotte Keller, DACVO, DECVO, she suggests that treatment may include the reduction of fat intake.
Currently, the Canine Eye Registration Foundation (CERF) does not deny certification to cavalier King Charles spaniels which are affected with corneal dystrophy, because the Genetics Committee of the ACVO classifies the disorder as a "breeder option" for CKCSs. However, the Canine Inherited Disorders Database recommends that all dogs suffering from corneal dystrophy not be bred.
The Cavalier King Charles Spaniel Club, USA recommends that, prior to breeding any Cavalier, the dog have a normal rating or be within CERF "breeder options" from a screening by a board certified veterinary ophthalmologist.
The Canine Health Information Center (CHIC) is a centralized canine health database sponsored by the AKC/Canine Health Foundation (AKC/CHF) and OFA. The CHIC, working with participating parent clubs, provides a resource for breeders and owners of purebred dogs to research and maintain information on the health issues prevalent in specific breeds.
AKC's national breed clubs establish the breed specific testing protocols. Dogs complying with the breed specific testing requirements are issued CHIC numbers. The ACKCSC requires that, to qualify for CHIC certification, cavaliers must have a CERF eye examination, recommending that an initial CERF exam be performed at 8 to 12 weeks, with a follow up exam once the dog reaches 12 months, and annual exams thereafter until age 5 years, and every other year until age 9 years. However, all that is required to qualify for a CHIC certificate is that the breeding stock be examined by a veterinary ophthalmologist. It does not require that the results of the examination show no eye disorders.
Crystalline Stromal Dystrophy in the Cavalier King Charles Spaniel. Crispin SM, Proc Am Coll Vet Ophthalmol 17:18, 1986.
Crystalline corneal dystrophy in the dog. Histochemical and ultrastructural study. Crispin SM. Cornea. 1988;7(2):149-61.
Ocular Disorders Presumed to be Inherited in Purebred Dogs. Genetics Committee, A.C.V.O. 1999.
Control of Canine Genetic Diseases. Padgett, G.A., Howell Book House 1998, pp. 198-199, 239.
Guide to Congenital and Heritable Disorders in Dogs. Dodds WJ, Hall S, Inks K, A.V.A.R., Jan 2004, Section II(65).
Breed Predispositions to Disease in Dogs & Cats. Alex Gough, Alison Thomas. 2004; Blackwell Publ. 44-45.
Ophthalmic Disease in Veterinary Medicine. Martin C.L. Manson Publ. 2005.
Visual Morbidity in Thirty-four Families with Schnyder Crystalline Corneal Dystrophy (An American Ophthalmological Society Thesis). Jayne S. Weiss. Trans Am Ophthalmol Soc. 2007 December; 105: 616–648. Quote: "Crystalline stromal dystrophy is the commonest canine corneal lipid deposition and is relatively common in the Cavalier King Charles Spaniel."
Canine Inherited Disorders Database: http://ic.upei.ca/cidd/disorder/corneal-dystrophy
The Eye and Systemic Disease. John Mould. 2008 WSAVA Congress. Quote: "Corneal Lipid ... Most common appearance is paracentral lipid dystrophy: ... Shelties and Cavalier King Charles spaniels."
Non-Ulcerative Corneal Disorders. Charlotte Keller. 2010 WSAVA Congress. Quote: "The White/Yellow/Grey/Blue Cornea: Lipid and mineral deposition in the cornea create a sparkly white, refractile appearance. The deposition of lipid in the cornea has been divided into three clinical types: 1) Crystalline stromal dystrophy--bilateral, axial or paraxial crystalline appearance without inflammation or vascularisation. The deposition of lipid in the cornea without the presence of another disease. Cavalier King Charles Spaniel, Husky Beagle, etc. 2) Lipid keratopathy (corneal lipidosis)--Arcus lipoides corneae--peripheral lesion bilateral ocular manifestation of systemic disease (hypothyroidism, systemic lipid abnormalities). 3) Corneal degeneration--primary or secondary to anterior segment disease (ulcerative keratitis, pannus). Treatment: May include the reduction of fat intake, the control of the underlying systemic diseases and control of ocular disease."
Ocular conditions affecting the brachycephalic breeds. Peter G.C. Bedford. RVC. Quote: "There are two types of disease which affect the eye of the brachycephalic breeds and both are directly or indirectly related to genetic predisposition. First and by far the commonest are those conditions which are due to be conformation of skull and are related to the exophthalmos which is the common feature of these breeds. Second there are those conditions which have been unwittingly bred into some brachycephalic breeds in the pursuit of desired breed characteristics. In this lecture I will present an overview of all the diseases that the small animal practitioner is likely to encounter in the brachycephalic breeds of pedigree dog. The fourteen breeds I have included for discussion are the Affenpinscher, Boston Terrier, Boxer, Bulldog, Cavalier King Charles and the King Charles Spaniels, (mesaticephalic) French Bulldog, Griffon Bruxellois, Japanese Chin, Lhasa Apso, Pekingese, Pug, Shih Tzu and Tibetan Spaniel. ... Corneal Lipid Dystrophy: The term applies to the characteristic cholesterol and triglyceride deposits in the superficial corneal stroma seen most commonly in the Cavalier King Charles Spaniel. It is clinically benign and seldom affects vision to any noticeable degree. ... Hereditary Cataract: Hereditary cataract is seen in the Boston Terrier and the Cavalier King Charles Spaniel. ... Microphthalmos (MoD): Again the American literature suggests that microphthalmos (MoD) may be inherited in the Cavalier King Charles Spaniel."
Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Blackwell Publ. 53.
A cloudy view? David L. Williams. April 2013. Quote: "What is happening in the cornea of this Cavalier King Charles Spaniel? This dog has a crystalline stromal lipid dystrophy – an inherited defect in how the keratocytes – the corneal cells - deal with lipid, leading to a deposition of lipid crystals in the centre of the cornea. It looks identical to Schnyder’s dystrophy in people as shown below, but whether the same gene mutation is present is currently unknown. In people this makes reading and driving at night difficult, but in the dog the lesion doesn’t interfere with vision (as they rarely read or drive at night!) and the lipid deposit is unlikely to develop markedly."
Cultivation of corneal epithelial cell sheets on canine amniotic membrane. Eunryel Nam, Ayaka Takahashi, Naoki Fujita, Keiko Tsuzuki, Ryohei Nishimura. Vet.Ophthalmology. July 2013;16(4):263-268. Quote: "Objective: To develop and assess canine corneal epithelial cell sheets cultivated from limbal stem cells on amniotic membrane. Procedures: Canine corneal limbal segments were obtained from six beagle dogs. Cryopreserved denuded amniotic membranes (obtained from Miniature Dachshund and Cavalier King Charles Spaniel breeds) from which the epithelial cells were removed were used as scaffolds. The limbal segments were cultured on these amniotic membranes with 3T3 feeder cells for 2 weeks. The harvested corneal epithelial cell sheets were stained with H&E for histologic analysis. The harvested sheets were analyzed immunohistochemically using a corneal epithelium-specific marker keratin 3(K3) and putative stem cell markers ABCG2, p63, and vimentin. Results: Cultivated cells from the corneal limbal tissues reached confluency in 7–8 days. The cultivated cells adhered to the denuded amniotic membrane and formed a sheet. The cultivated cell sheet was transparent and consisted of five to eight layers. K3 was observed in all layers and ABCG2, p63, and vimentin were notably present in the basal layer of the cultivated canine epithelium by immunofluorescence. Conclusions: Canine corneal epithelial cells were successfully cultivated on the canine amniotic membrane. The cultivated epithelial sheets contained putative stem cells in the basal layer and had a stratified epithelium."
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."