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Progressive retinal atrophy is a degenerative disease of the retina; the layer at the back of the eye responsible for vision. This is an inherited disease that causes progressive blindness over a period of months or years. It can occur in almost any breed but is most commonly seen in miniature and toy poodles, cocker spaniels and Labrador retrievers.
What are the signs of PRA?
It is likely that you notice your dog becomes ‘night blind’. They may become nervous at night and reluctant to enter dark rooms or go outside in low light levels. As the disease progresses, daytime vision becomes impaired and they will start to bump into unfamiliar objects.
You may also notice an increased “eye shine”; the pupil will appear more dilated and the eye will have a brighter reflection when the dog looks at the light.
Cataracts are a common secondary complication seen with PRA, in these cases removal of the cataract is not recommended as vision is unlikely to be restored.
Diagnosis of PRA is usually made by examining the back of the eye with an ophthalmoscope to look for characteristic signs of retinal degeneration. If the retina cannot be examined, for example if secondary cataracts are present, an ‘ERG’ may have to be performed. An ERG (electroretinogram) measures the electrical activity (and therefore function) of the retina.
DNA tests are also available for some breeds of dog. DNA tests are particularly useful in young dogs or those which may be used for breeding because the tests can identify affected dogs before they develop signs of PRA. They can also identify carrier animals, who will not develop PRA themselves but may pass the disease on to their offspring.
There is unfortunately no effective treatment for PRA and affected animals are likely to become totally blind over time. Dogs, however, adapt extremely well and often cope well without their sight. Please request a copy of our additional handout “Living with a Blind Dog” for more information.
There is an antioxidant nutritional supplement called ‘Ocu-Glo’ that the manufacturers claim slows the progression of PRA and cataract. Antioxidants have been shown to be beneficial in human retinal diseases however, there is very limited evidence available for this in animal studies. They may be helpful and are unlikely to do your pet any harm if this is something you would like to trial.