Progressive retinal atrophy is one of the most widely spread chronic and progressively disabling vision problems that can affect dogs, and which is a hereditary condition passed on to subsequent generations of dogs through their breed lines. There are a whole host of different types of progressive retinal atrophy that are all caused by different mutated or faulty genes, although all of them lead to eventual blindness in dogs that inherit the active form of the condition.
While the effect that this gradual and irreversible blindness has on affected dogs is always the same, identifying the gene mutations responsible for the condition requires a different form of DNA test for each variant.
The different variants of the condition in turn tend to be prevalent within different breeds of dog, and in this article, we will look at the GR-PRA1 variant of the condition, which is a particular threat to the golden retriever dog breed.
The Kennel Club, in association with The British Veterinary Association, strongly recommends health testing for progressive retinal atrophy in breeds known to be at high risk of the condition, in order to curb the dissemination of the faulty gene that causes the disorder in the wider gene pool for the breed.
This means that anyone who owns a golden retriever and that is thinking or breeding from them, and anyone who wants to buy a golden retriever and know for sure if they will be affected with the condition or not, is advised to have their dog tested, or ask about the test results from the breed line.
The GR-PRA1 version of progressive retinal atrophy is a form of the condition that leads to a degeneration of the rods and cones of the eyes, which are the parts of the retina that receive and interpret visual messages relating to light and colour. The rods and cones then pass this information about what the eyes have received to the brain, where they are turned into the visual picture that your dog sees of the world around them.
When these rods and cones degenerate, the dog cannot either receive or interpret light and colour cues, which causes a total loss of vision.
If you want to learn about the basics of progressive retinal atrophy as a general condition, including how it affects dogs and the impact it can have upon them, check out this article.
The GR-PRA1 form or progressive retinal atrophy is present in the gene pool of the Golden retriever dog breed, which means that any untested dog of this breed may carry or develop the condition. Additionally, cross breeds and hybrid breed dogs that contain some golden retriever ancestry are also at risk of the condition, which means that golden retriever hybrid breeds like the Goldendoodle are at risk of inheriting the condition too.
It can be difficult to notice the condition’s development during the early stages of GR PRA1 in dogs, as the condition usually begins with night blindness and then progressively develops to lead to complete blindness.
Until the condition begins to exhibit symptoms, the only way to know if a dog will be affected by the condition, or if they are a carrier for it and so, can pass it on to their offspring, is by means of DNA testing.
GR PRA1 is an autosomal recessive condition, which means that puppies need to inherit the right combination of affected genes from their parent dogs in order to carry or develop the condition themselves.
If both parent dogs are affected by the condition, all of their offspring will be affected too. If both are clear, their litter will be clear too.
If only one dog is affected and the other is clear, the puppies will become carriers of the condition, but not affected by it themselves. If one of the dogs is affected and the other is a carrier, half of their puppies will be carriers, and the other half affected.
If one of the dogs is a carrier of the condition while the other is clear, half of their litter will be carriers and half affected. If both parents carry the condition but are not affected themselves, 50% of their puppies will be carriers too, while 25% will be affected and 25% clear.
The method of identifying affected and carrier dogs for GR PRA1 progressive retinal atrophy is by means of DNA testing, which requires either a blood sample, dewclaw sample or buccal swab, which is a swab of the cells from the inside of your dog’s cheek.
Your local vet can take the appropriate sample for you, which then needs to be sent off to an approved laboratory that can perform the test. To find out more about laboratories that can perform the test, check out this information on The Kennel Club’s website.