Progressive Retinal Atrophy (PRA) is by definition a genetic condition resulting in degeneration of the retina and blindness in affected dogs. There are many different types of PRA with different modes of inheritance and different ages of onset but the most common type is seen in middle aged dogs of affected breeds and is due to a recessive gene. Classic breeds for PRA include the Miniature and Toy Poodles, Cocker Spaniels, Labrador Retrievers, Golden Retrievers and the Australian Cattle Dog. A number of different genes have been identified to date, the most common is the prcd or progressive rod-cone dysplasia gene. The first sign observed is usually night blindness with poor visual function in low light conditions progressing variably over months to years to complete blindness. There is no treatment.
Traditionally there was no way to diagnose this condition until the dog developed the condition in middle age by which time it was probably towards the end of its breeding life. This made the culling of affected breeding stock difficult with resultant continuing propogation of the gene. There has been an explosion in the development of DNA blood tests in the last 10 years meaning now that in many breeds we can identify affected individuals and carriers at an earlier age. In some breeds such as the miniature and toy poodle and the miniature schnauzer there is more than one gene suspected as a cause of the condition and there may only be a DNA test for one of the genes.