Progressive Retinal Atrophy, Rod-Cone Dysplasia 3 is an inherited eye disease affecting dogs. Progressive Retinal Atrophy, Rod-Cone Dysplasia 3 is an early onset disease affecting the Photoreceptor Cells of the Retina and results in the progressive loss of vision. Affected dogs have abnormal thinning and degeneration of the retina beginning around 4 weeks of age. Signs of progressive retinal atrophy including changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam by 6 to 16 weeks of age. Rod photoreceptor cells degenerate first resulting in loss of peripheral vision and night vision. As the disease progresses, cone photoreceptor cells also degenerate resulting in complete blindness. Most affected dogs are completely blind by 1 year of age, but some may retain limited sight until 3 to 4 years of age.