What are the signs & symptoms that develop in affected dogs?
A dog with decreased vision may be reluctant to go down stairs or go into a dark room or outside at night. They may bump into door frames or corners and have difficulty fetching toys. You may notice a characteristic eyeshine due to increased reﬂectivity of the tapetum, the layer of the eye that reflects light. The dog's discernible visual impairment will typically lag behind changes observed by a veterinarian and electroretinogram (ERG) abnormalities.
When do signs and symptoms develop?
Changes may be observed as early as 2 years of age, leading PRA to be “suspected.” The average age of the PRA “affected” diagnosis is 9 years, but varies. The disease progresses slowly, as some affected dogs may still have some eyesight left at 13 years of age.
How do vets diagnose this condition?
PRA is diagnosed by examination of the back of the eye (the "fundus"). In the early stages, it may be difficult to observe changes to the retina, but as the disease progresses, a veterinarian will notice increased reflectivity, thinning of the retinal blood vessels, and atrophy of the optic nerve. Changes affect both eyes equally, helping to distinguish PRA from other retinal diseases. A veterinary ophthalmologist can perform an ERG, which measures the electrical activity, and thus the function, of the retinas. An ERG is crucial to evaluate for PRA prior to considering cataract surgery.
How is this condition treated?
Currently, there is no widespread treatment for progressive retinal atrophy. However, gene therapy is an evolving field.
What actions should I take if my dog is affected?
- Because the condition is progressive, dogs will adapt to the gradual vision loss over time. Owners should help affected dogs navigate their homes and the outside world by keeping furniture in the same location, making sure they are on a leash when in unfamiliar territory, and training them to understand verbal commands or using scent markers.
- A dog may develop cataracts later in the disease progression. Oral antioxidant therapy has been shown to improve retinal function in normal dogs as well as decrease oxidative stress on lens cells, which can help delay cataract formation. Ask your vet about supplements to give to your dog.