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Progressive retinal atrophy

Progressive retinal atrophy (PRA) is a group of genetic diseases characterized by degeneration of the retina that occurs bilaterally. It is seen in certain breeds of dogs and more rarely, cats. It causes progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment. PRA is similar to retinitis pigmentosa in humans.
Progressive retinal degeneration is not a painful condition so your pet will not have a reddened eye or have increased blinking or squinting. For this reason most clients will not notice the early stages of the condition. Some clients will notice an abnormal shine coming from their pet's eyes. This abnormal shine is because the pupils are dilated and don't respond as quickly to light as pupils of normal dogs. The earliest signs of PRD include night vision difficulties that in most cases will progress to day blindness. Clients will often remember that their pets seemed disoriented when going out to the yard at night and they had to leave a light on for them. Night blindness may be manifested by a pet that is afraid to go into a dark room. Occasionally these pets will get lost in their own home after the lights have been turned off.

Progressive vision loss in any dog in the absence of glaucoma or cataracts can be an indication of PRA. It usually starts with decreased vision at night, or nyctalopia. Other symptoms include dilated pupils and decreased pupillary light reflex. Fundoscopy to examine the retina will show shrinking of the blood vessels, decreased pigmentation of the nontapetal fundus, increased reflection from the tapetum due to thinning of the retina, and later in the disease a darkened, atrophied optic disc. Secondary cataract formation in the posterior portion of the lens can occur late in the disease. In these cases diagnosis of PRA may require electroretinography (ERG). For many breeds there are specific genetic tests of blood or buccal mucosa for PRA.

There is no possible treatment for PRD although a number of vitamin therapies have been suggested by various people. One such vitamin "Ocuvite" manufactured by Stortz has been recommended for people with retinitis pigmentosa and some patients claim that their vision is improved somewhat. At this time, none of the vitamin treatments have been proven to be effective scientifically, so use of Ocuvite must be deemed a naturopathic remedy rather than a medical treatment.



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About Your Dog, is your online ressource of articles on puppy and dog health, dog training and information about your pet dog