Dogs with degenerative PRA are born with normal rods and cones, but the cells start to break down sometime during adulthood. This slowly progresses into blindness, but the progression and age at which the majority of vision is lost will vary depending on the breed and the individual.

Progressive Retinal Atrophy (PRA) is a term used to describe a group of genetic disorders that eventually result in loss of vision for dogs. Although the time period can vary, many dogs will lose their sight entirely within 1-2 years of symptoms.