Progressive Retinal Atrophy (PRA)
What is PRA?
Progressive Retinal Atrophy (PRA) is an inherited disease of the retina (tissue layer at the back of the eye containing the rods and cones) where the retina slowly degenerates with time.
How is PRA inherited?
The mode of inheritance for PRA varies with the breed. In most dogs, it is an autosomal recessive trait although some exceptions exist.
What are the signs of PRA?
Dogs with PRA usually lose their night vision before their day vision. With time the retina will completely degenerate leading to blindness. Fortunately, this disease is not painful.
How is PRA diagnosed?
PRA can be diagnosed by a blood test (DNA testing) in certain breeds, retinal testing by electroretinogram (ERG), or through a complete eye examination. An ERG will indicate PRA earlier than an eye exam.
Diagnosis of this disease is very important in breeding animals because it is hereditary and can be passed on to future generations! Dogs with PRA should not be bred.
How is PRA treated?
There is, unfortunately, no treatment for retinal degeneration and the blindness that it causes, but it is not painful. Animals with PRA may develop cataracts as a result of the retinal disease. Vision will not improve with cataract surgery. If the cataracts cause eye disease (immune system attacking the cataract), further treatment may be needed.
What are the other diseases that cause signs like PRA?
PRA must be distinguished from inflammatory or other diseases of the retina that are potentially treatable and reversible. The clinical signs can be the same as other diseases.
Blindness can also be caused by glaucoma, uveitis, and central nervous system diseases.
Dogs that are blind can still have a wonderful quality of life!
PRA produces a slow blindness that does allow time for dogs to adjust. Dogs have many other senses like hearing and smell that far exceed our own.