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Progressive Retinal Atrophy (Discovered in the Swedish Vallhund)

Progressive Retinal Atrophy (PRA) causes the light sensitive photoreceptor cells in the eye to degenerate, leading to night blindness.

Found in

1 in 5,000 dogs

in our testing

Key Signs

Retinal degeneration, Night blindness, Vision loss

Age of Onset

1 to 4 yrs

Junior to adult onset

Inheritance

Autosomal Recessive

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.

Likelihood of the Condition

Moderate-high likelihood

At risk dogs are likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with PRA

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.

For Veterinarians

Here’s what a vet needs to know about PRA

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.

For Breeders

Planning to breed a dog with this genetic variant?

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.

Technical Details

Gene MERTK
Variant Insertion
Chromosome 17
Coordinate Start 36,338,058
Coordinate End 36,338,059

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

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