IN JULY 2024 at the University of Cambridge, scientists identified the genetic mutation that causes Progressive Retinal Atrophy – PRA in dog breeds like the English shepherd, border collie, labradors, poodles, cocker spaniels and the Australian cattle dog, cats can also suffer from it.
The disease results in incurable blindness by the age of four or five, unlike humans, dogs cannot let us know their vision is deteriorating, it is only when the animal starts running into things that it becomes obvious.
PRA is a group of inherited diseases that cause progressive degeneration of the light sensitive cells at the back of the eye. There is no treatment.
Researchers say that their work with dogs could shed light on the human version of the disease: Retinitis Pigmentosa, and potentially identify targets for gene therapy in the future.
The new discovery means that PRA can be completely eliminated from the dog population very quickly – if breeders do the DNA test.
The genetic mutation identified by the team is recessive, which means it only causes blindness if the dog inherits two copies of it (one from each parent).
If the animal has only one copy, that makes him a carrier and he will not develop PRA, but can pass the mutation on to his/her puppies. If two carriers are bred together, about one in four of the puppies will be affected.
By identifying dogs that carry the disease before their eyesight starts to fail, it provides a tool to guide breeding decisions so the disease is not passed on.
Owners do not realise their dog has PRA until the dog has reached middle age, by which time it may have been bred and passed on the faulty gene. This fact has made it a difficult disease to control.
Orivet is one company in Australia that offers a DNA saliva test kit for this disease, the test is sent to the USA or England and it costs around $75.
