What is Progressive Retinal Atrophy (PRA)?
PRA is a collective term used to define a number of genetic disorders in dogs that lead to retinal degeneration. These are hereditary diseases, meaning that dogs inherit the genes that cause the disease from their parents. Purebred and mixed breed dogs can be affected, with toy poodles and Labradors being especially common. Most of the diseases are autosomal recessive, meaning a dog has to have both copies of the problematic gene, but some are autosomal dominant or sex-linked. The actual genetic mutation is known for many breeds, and can be tested for.
What are the signs of Progressive Retinal Atrophy?
Onset of this disease is gradual, and usually signs are not apparent to the owner until the disease is quite advanced, which can occur at a young or older age. Breed and the specific genetic mutation play a role in how quickly the disease progresses. Nyctalopia, or trouble seeing at night, is often the first noticeable sign. This occurs because the rods of the retina are affected first with most forms of PRA, and the rods are important for seeing in the dark.