Progressive Retinal Atrophy, Early Onset (Spanish Water Dog Type)

General Information: Progressive Retinal Atrophy, Early Onset (PRA-EO), specifically in Spanish Water Dogs, involves the early deterioration of photoreceptor cells in the retina—both rods and cones—which are critical for vision in low-light and normal light conditions, respectively. Dogs affected by PRA-EO can start showing symptoms of vision impairment as early as 1.5 years old, with progressive worsening that often results in substantial vision loss or complete blindness by the age of 4.5 years. Initial symptoms include night blindness and a reduction in peripheral vision. As the condition advances, dogs may lose their ability to see in well-lit conditions as well. This degenerative process is often observable through changes in the appearance and reflectivity of the tapetum—a layer of tissue in the eye that can be examined during a veterinary eye exam.

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 PDE6B gene is crucial in identifying carriers of the early-onset form of Progressive Retinal Atrophy (PRA-EO) in Spanish Water Dogs. This condition is autosomal recessive, meaning that a dog needs to inherit two copies of the mutated gene, one from each parent, to develop the disease. Dogs carrying one copy of the mutation do not typically show symptoms but can pass the mutated gene to their offspring. When two carriers are bred, there is a 25% chance their puppies will inherit PRA-EO, and a 50% chance they will be carriers of the PDE6B mutation. To prevent the propagation of this condition, it is recommended not to breed carriers of the mutation with one another. Implementing reliable genetic testing helps breeders make informed decisions, aiming to reduce the incidence of this disease in future generations. While a clear genetic test indicates no increased risk for PRA due to this specific mutation, other forms of PRA or different mutations could still affect the breed, underscoring the importance of comprehensive testing and careful breeding practices.