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 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.
Typically, the first signs of PRA in Swedish Vallhund can be observed at 4 years of age. Degeneration of the light sensitive photoreceptor cells, called rod cells, start causing night blindness around 6 years of age. The progressive condition also results in the loss of cone cells. However, the condition rarely progresses to complete blindness and affected dog often maintain sufficient day vision for several years, often through their natural life span. It must be noted, that even when the most typical age of onset is around 4 years of age, the age of onset can vary from 1 year to up to 12 years.
There is no curative treatment for the disease. Management of the disease includes keeping the dog’s environment as stable and safe as possible.
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.
All coordinates reference CanFam3.1
Everson, R., Pettitt, L., Forman, O. P., Dower-Tylee, O., McLaughlin, B., Ahonen, S., … Ricketts, S. L. (2017). An intronic LINE-1 insertion in MERTK is strongly associated with retinopathy in Swedish Vallhund dogs. PLoS ONE, 12(8), 1–14. View the article