Fun with fido

Progressive Rentinal Atrophy (PRA) in Dogs

This is a genetic, inherited disease of the retina (the "film" in the camera), which occurs in both eyes
simultaneously. The disease is nonpainful, and there is no cure for it. The eyes are genetically
programmed to go blind. PRA occurs in most breeds of dogs and can occur in mixed breeds also. It is
recessively inherited in all breeds studied, with the following exceptions: PRA is dominantly
inherited in Old English Mastiffs and Bullmastiffs, and PRA is sex-linked and found primarily in
male dogs in the Siberian Husky and Samoyed breeds.

Clinical signs vary from the dog first becoming night blind in the early stage of PRA (not able to see in
low light surroundings) to the entire visual field in all light levels becoming affected, which is
advanced PRA. The pupils are usually dilated, and owners often notice a "glow" and increased "eye
shine" from the eyes. All dogs with PRA will eventually develop blindness from advanced PRA, and
this time frame until the dog is blind varies considerably from dog to dog, but usually takes at least 6
months from the time of diagnosis, and can rarely take years until the dog is completely blind.
Although no treatment for PRA is possible to stop the disease, nutritional antioxidant
supplementation for retinal health may help slow the deterioration of the retina to "buy some time"
before the blindness inevitably happens. Many veterinary ophthalmologists do not recommend oral
nutritional therapy for dogs with PRA, because there has been no research on the effect of oral
antioxidants on dogs with PRA. However, Animal Eye Care believes that in some of these PRA
patients, specific oral antioxidant therapy can delay the progression of blindness. Blindness is not
avoided, however, in any PRA patients. If an oral antioxidant were used, it would be continued until
complete vision loss occurred.

What to do if you suspect PRA:

Have your dog examined by a board certified veterinary ophthalmologist to determine if this disease
is indeed present. If you are located in the Pacific Northwest, you may contact our office to schedule
a comprehensive ophthalmic examination. Dogs with PRA should not be bred, and the breeder that
you received your dog from should be notified that the dog is affected, so the breeder can alter their
breeding program in future. It is important to understand that dogs with PRA are happy dogs. Their
eyes don't hurt, and they adjust very well to their slow loss of vision. In fact, if a dog were destined to
become blind and Dr. McCalla could pick the disease, it would be PRA, as the vision loss is slow and
nonpainful, and the dog is given much time to adjust to its vision loss.

It is important to realize that it is OK to grieve about your pet's vision loss, but you must not put your
sad feelings in your dog's head--they aren't really there! Your dog is not suffering. They adjust well to
their vision loss, and it is by far hardest to deal with on the owner's side. Your dog's job description
has not changed. Your blind dog is happy as long as its routine is stable. From your dog's point of
view, life continues to be great-- you are there as always, and they just need to use their other keen
senses a bit more to get the same information they used to view. Keep household furniture in its
place, and consider purchasing the book "Living With Blind Dogs" by Caroline Levin. Animal Eye
Care also sells this book. It is the only book of this subject matter, and is beneficial in helping owners
and their affected pets adjust to the vision loss.

Dogs with PRA can develop cataracts late in the disease process. Cataract surgery would never be
done, as it would not help the dog to see. However, cataracts can cause pain and damage to the eye,
and if the eyes look very cloudy to you, please call Animal Eye Care for a reexamination as soon as
possible.

There are DNA blood tests available, to determine if dogs are likely affected with PRA, are likely
carriers for PRA, or are not likely carrying the PRA gene. This test is available for the following
breeds: Australian Labradoodle, Briard, Cardigan Welsh Corgi, Chesapeake Bay Retriever, Nova
Scotia Duck Tolling Retriever, English Cocker Spaniel, Irish Setter, Labrador Retriever, Portuguese
Water Dog, Toy and Miniature Poodles, Sloughi, Old English Mastiff and Bullmastiff, Miniature
Schnauzer, Siberian Husky, and Samoyed. Please visit the web site for further information
(www.Optigen.com). Additionally, studies for Late Onset PRA in Tibetan terriers and PRA in Jack
Russell Terriers are being conducted at the University of Missouri-Columbia. For blood sample
collection kits and more information about these research studies, please contact: Liz Hansen,
coordinator of Veterinary Information, Dr. Gary Johnson's Laboratory at hansenl@missouri.edu
[phone number: (573) 884-3712]. Please also view the article about the disease in Tibetan Terriers at
the CERF web site (www.vmdb.org).