Junior to adult onset
For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.
At risk dogs are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
In the Lhasa Apso breed, the onset of clinical signs is observed with initial loss of vision in dim light (night blindness) that gradually progresses to total blindness. The first signs are caused by loss of rod photoreceptor cells required for vision in dim light followed by reduction of the visual field and blindness as the cone cells of the retina also degenerate. The onset of clinical signs typically occurs at mid-age, although age of onset can vary.
Although this condition results in gradual vision loss, and eventual blindness, many dogs adapt remarkably well to vision loss. Although there is no treatment, owners should be advised that the disease development is gradual and their dog may need assistance in unfamiliar surroundings as clinical signs progress. Owners may find that it is helpful to keep the dog's main environment as stable as possible (avoid moving furniture, etc.) to help them navigate as vision worsens.
There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.
This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the PRA mutation can be safely bred with a clear dog with no copies of the PRA mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the PRA mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the PRA mutation could develop due to a different genetic or clinical cause.