Dogs don’t rely on their eyesight like humans do. Their eyesight isn’t as strong as ours, so their sense of smell in particular tends to be much more important.
And unfortunately, dogs can sometimes become blind, losing the eyesight that they did have. While dogs can adapt to going blind, and will still love playing with the best dog toys, it’s not ideal, and can be avoidable. There are a few different reasons why dogs might go blind, including a range of inherited eye conditions.
One such condition is progressive retinal atrophy, or PRA, which affects the light-sensitive cells at the back of the eye. It affects over 100 breeds, can be caused by multiple different genetic variants, and there’s no treatment.
At first, it might affect vision in dimmer lighting, before eventually leading to full blindness. Sometimes, symptoms don’t appear until dogs are a few years old, meaning that they may have already passed it on to their puppies.
However, Shola, an English Shepherd who was forced to retire as a mountain rescue dog due to the condition, has helped scientists create a new test that could mean the end of PRA.
Katherine Stanbury, the first author of the research, and her University of Cambridge colleagues, have been able to identify the genetic variant responsible for the condition in English Shepherds, and have also developed a £48 DNA test that shows whether dogs have two, one, or no copies of the variant.
Though the variants that cause PRA are generally breed-specific, they’re now planning on screening any dog affected by a genetic eye condition for the new variant.
Shola and her brother’s breeder brought the pair to the team, who then carried out whole genome sequencing on their DNA. However, they found that neither had genetic variants previously associated with PRA, suggesting that there was another variant.
The team were able to identify the variant responsible, and it’s hoped that the DNA test will help dog parents to identify English Shepherds with PRA early on, so they can avoid using them for breeding — PRA could then be eliminated from the breed.
You can still breed from carriers, which have one copy of the variant, as long as you breed them with dogs who have no copies.
Shola has had puppies, but the puppies’ father has been tested, too, and won’t develop PRA. Stanbury said, “Two of her daughters have just completed their mountain rescue training with Mountain Rescue England. And one of her sons is a therapy dog.”
“[The owners] know that none of those dogs are going to go blind and have all that training be wasted,” she added — and one of them recently saved a man’s life.
For more about dog eyesight, are dogs color blind? Or is that a myth?
