Progressive retinal Atrophy, golden retriever 2 (GR-PRA2) is a late-onset inherited eye disease affecting golden retrievers which is often accompanied by a host of other clinical signs (described below) resembling a condition in humans called Bardet-Biedl syndrome. Affected dogs begin showing clinical symptoms related to retinal degeneration at around 4 to 5 years of age on average, though age of onset can vary. Initial clinical signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the Retina called the Tapetum that can be observed on a veterinary eye exam. Progression of the disease leads to thinning of the retinal blood vessels, signifying decreased blood flow to the retina. Affected dogs initially have vision loss in dim light (night blindness) and loss of peripheral vision, progressing to complete blindness in most affected dogs.
In addition to progressive retinal atrophy, affected dogs may show other clinical signs of variable severity including cataracts, obesity, an abnormally broad muzzle, flat forehead, poor sense of smell, short stature, overgrowth of gum tissue (gingival hyperplasia), increased distance between teeth, chronic kidney disease, heart valve degeneration, irregular heat cycles, small testicles, low sperm count, sperm cell defects, and decreased male libido. However, each affected dog may develop a unique combination and severity of clinical signs.