Progressive Retinal Atrophy, Rod-Cone Dysplasia 2 (Collie Type)

General Information: Progressive Retinal Atrophy, Rod-Cone Dysplasia 2 (PRA-rcd2) in Collies is characterized by the early and rapid degeneration of both rod and cone photoreceptor cells in the retina, essential for dim and bright light vision, respectively. Symptoms start as early as 16 days of age with the thinning and degeneration of the retina, progressing to night blindness and loss of peripheral vision by about 6 weeks. By 3.5 to 4 months, changes in the tapetum—a reflective layer behind the retina—become apparent during veterinary eye exams. The condition escalates quickly, with affected dogs often becoming completely blind by the age of 6 to 8 months. The rapid progression of this condition significantly impacts the quality of life for affected puppies, often necessitating enhanced care or adjustments in their living environment.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing for the RD3 gene is essential to determine if a dog is a carrier of Progressive Retinal Atrophy, Rod-Cone Dysplasia 2 (PRA-rcd2). This condition is inherited in an autosomal recessive manner, meaning that a dog must inherit two copies of the mutated gene, one from each parent, to exhibit symptoms of the disease. Dogs that are carriers possess one copy of the mutation but typically do not show any signs of the disease; however, breeding two carriers presents a 25% risk of producing affected offspring and a 50% chance of producing another carrier. To prevent the propagation of this debilitating condition, it is crucial not to breed known carriers together. Implementing responsible breeding practices through reliable genetic testing helps ensure the health of future generations by aiming to eliminate this mutation from breeding lines. Despite the focus on the RD3 gene, breeders should be aware that other types of PRA caused by different mutations could still affect the breed, so a negative RD3 test does not rule out other forms of the condition.