Progressive Retinal Atrophy in Cavaliers:
A Slow Death of the Retina
Progressive retinal atrophy (PRA), also known as progressive retinal degeneration (PRD), is a genetic disease in the Cavalier King Charles Spaniel which causes blindness. PRA is inherited by an autosomal recessive gene. It is a slow but progressive degeneration or death of the retinal tissue. It is similar to retinitis pigmentosa in humans.
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.
Symptoms
It's earliest signs may be overlooked, and owners may not notice the early stages of the disorder. It usually begins with an an abnormal shine in the Cavalier's eyes. This is due to the pupils being dilated and not responding as quickly to light as pupils of normal dogs. Other early indications include night vision difficulties that usually progress to day blindness.
Late in the progression of PRA, cataracts may develop. See Cataracts for more information.
Diagnosis
Diagnosis should be conducted by a veterinary ophthalmologist. Usually the veterinarian first examines the dog with an indirect ophthalmoscope. An electroretinogram (ERG) is essential for an accurate diagnosis, because cataracts also may develop in the eyes of dogs suffering from PRA, and they may interfere with the ophthalmologist's examination of the retina. Examination using the ERG may require that the dog be anesthetized. The ERG is sensitive enough to diagnose dogs with PRD before they begin to demonstrate signs of the disease.
Treatment
There is no possible medical treatment for PRA.
Breeders' Responsibilities
The Canine Inherited Disorders Database recommends that Cavalier King Charles Spaniels suffering from PRA not be bred. Any littermates of breeding stock having PRA should be taken into consideration.
The Cavalier King Charles Spaniel Club, USA recommends that, prior to breeding any Cavalier, the dog have a normal rating 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.
All Cavalier breeding stock should be examined by board certified veterinary ophthalmologists at least annually and cleared by the veterinary specialists for PRA, the closer the examination to the breeding the better.
Related Links
Eyes
Cataracts
Questions for
Breeders
American College of Veterinary Ophthalmologists (ACVO)
Veterinary Resources
Control of Canine Genetic Diseases. Padgett, G.A., Howell Book House 1998, pp. 198-199, 241.
Guide to Congenital and Heritable Disorders in Dogs. Dodds WJ, Hall S, Inks K, A.V.A.R., Jan 2004, Section II(256).
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.
Canine Inherited Disorders Database: http://www.upei.ca/~cidd/Diseases/ocular disorders/Progressive Retinal Atrophy.htm
