Signs, Symptoms & Treatment of Progressive Retinal Atrophy (PRA) & Vision Loss in Dogs and Cats
January 20th, 2015 | Posted in Medical Articles
Progressive retinal atrophy (PRA) is an untreatable but painless disease of the retina that leads to blindness.
Light reaches the retina forms an image much as it does on the film in a camera. Cells in the retina called rods and cones change this light into electrical impulses that travel along the optic nerve to the brain where the electrical impulses are translated into the sensation we know as vision.
In PRA, the rods and cones degenerate and die, therefore the light cannot be changed into an electrical impulse and vision is impaired. Rods, which provide vision in dim light, are often affected first, therefore the animal may start to bump into objects when lighting is dim or dark (night blindness). Cones provide color and daytime vision and degenerate more slowly. As the cones degenerate, the animal may adjust and may behave normally early in the course of the disease. It may take months to years for the loss of rods and cones to become severe and lead to complete blindness.
Progressive retinal atrophy is diagnosed by direct observation using an instrument called an ophthalmoscope, or by electroretinography (ERG). An ERG is an electrical test of retinal function. PRA is an inherited disease in many breeds of dogs and some cats including but not limited to Miniature Poodles, Schnauzers, Yorkshire Terriers, English Cocker Spaniels, Irish Setters, and Collies. There is no specific treatment or cure for PRA. Because the disease is inherited, affected animals should not be bred. Most dogs and cats adapt well to blindness if their environment is not continually changed. The major concern is for the safety of affected animals. Swimming pools are particularly hazardous because blind animals cannot always find their way out if they fall in. You must help your pet avoid obstacles, pedestrians, bicyclists and automobile drivers who expect animals to move out of the way. You will quickly learn how to be a “seeing-eye” person for your companion.
Numerous internet websites and books are available that contain information that can be helpful for both you and your pet as you adapt to vision loss. One book that we recommend is “Living With Blind Dogs” by Caroline Levin.