Progressive Retinal Atrophy (PRA) in Dogs
Progressive Retinal Atrophy, or PRA, is a genetic condition that causes blindness in dogs by destroying the rods and cones in the eyes. There are two main forms of PRA. The inherited condition, where the photoreceptors (rods and cones) never develop properly and lead to blindness in young dogs, is the less common form. The more common form, generalized photoreceptor degenerative disease, is seen in dogs 3-9 years of age and causes blindness to develop more slowly. Continue reading to learn more about this condition, including symptoms, testing, and potential treatments.
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Progressive Retinal Atrophy is a Genetic Condition
Both forms of PRA are a result of genetics. There are many different genes involved and certain breeds are at a higher risk, but this can affect any breed or mixed breeds.
With the inherited photoreceptor dysplasia, the rods and cones never form properly, causing blindness in young dogs. This is more common in certain breeds, such as Norwegian Elkhound, Irish Setter, Collies, Cardigan Welsh Corgi, Mini Schnauzers, Pit Bulls, Dachshunds, Siberian Husky, English Mastiff, and Bull Mastiffs.
The degenerative form affects dogs 3-9 years of age and tends to cause loss of night vision first as the rods are destroyed before the cones. The rods are responsible for night vision. However, the cones will also eventually be affected leading to total blindness. Breeds more commonly affected include Labs, Golden Retriever, English Cocker Spaniel, American Cocker Spaniel, Portuguese Water Dog, Chesapeake Bay Retriever, Australian Cattle Dog, and Nova Scotia Duck Tolling Retrievers.
Symptoms of PRA in Dogs
Dogs with the more common, degenerative form of PRA, tend to have a loss of night vision first. You may notice your dog being more hesitant to move around at night or when the lights are dim. Other symptoms include:
- Dilated pupils
- Sluggish/slow pupil response
- Cataract formation
- Poor nighttime vision, then progresses to poor daytime vision
- BOTH eyes are affected
- Bumping into objects
How is Progressive Retinal Atrophy diagnosed in dogs?
A good physical exam and eye exam are the place to start. A referral to the veterinary ophthalmologist is often recommended for a complete fundic exam (exam of the back of the eyes), called Funduscopy.
A maze test can help assess vision. Setting up a maze for the dog to walk through both in dim and bright light helps assess the amount of vision loss present.
Electroretinography measures the photoreceptor function. This is a good test for litters of puppies that may be affected and for dogs that do not have visible funduscopic degeneration. Anesthesia or sedation is needed for this test.
Genetic tests are also available to see if your dog is at risk for developing PRA. Many genes may be involved. Blood or cheek swab tests are available. These do not guarantee your dog will develop PRA but will let you know if they are at a higher risk and if they should not be bred so the genes are not passed on.
Breeding dogs should get a Certification Eye Exam if genetic tests are not available. This is done with a veterinary ophthalmologist. This test in the USA is overseen by the Orthopedic Foundation of America (OFA).
Treatment Options for Dogs with Progressive Retinal Atrophy
There are currently studies being conducted on gene therapy for PRA. Subretinal gene therapy has restored vision in dogs with one certain type of cone dysplasia.
Oral antioxidants, such as Ocu-Glo, may be recommended to improve retinal function and delay cataract formation.
Unfortunately, at this time, all dogs with rod-cone dysplasia or degeneration will lose all vision and go blind eventually. Since dogs with the more common, degenerative form, often lose vision slowly and lose night vision first, you can help them by adding in night lights, lights on the collar to help them see in dim lighting, and more lighting in general inside and outside the home.
Keep the furniture/floor layout of the home consistent so your dog can memorize the area and better navigate even when their vision is lost.
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