Scientists May Have Stopped a Form of Inherited Blindness in Dogs

• July 22, 2024
• Ernie Mundell HealthDay Reporter

In her youth, Shola, an English Shepherd Dog, was a member of the Edale Mountain Rescue Team, a corps of U.K. pooches charged with helping hurt and stranded hikers.

But Shola was retired as part of the Rescue Team after a rare genetic disease affecting dogs, called progressive retinal atrophy (PRA), robbed her of her sight.

It's too late for Shola, but new research has led to a gene test that could prevent the disease from ever being passed down to puppies -- perhaps someday eliminating PRA from dog populations for good.

“Once the dog’s eyesight starts to fail, there’s no treatment – it will end up totally blind,” explained study first author Dr. Katherine Stanbury, a veterinary researcher at the University of Cambridge.

Often an owner may not even realize their dog has PRA until middle-age, long after puppy breeding may have occurred.

However, “now we have a DNA test, there’s no reason why another English Shepherd Dog ever needs to be born with this form of progressive retinal atrophy – it gives breeders a way of totally eliminating the disease," Stanbury said in a Cambridge news release.

The key was pinpointing which gene or genes led to the vision-robbing condition.

Stanbury's team did so by comparing DNA samples from six English Shepherds with PRA and 20 without it.

The Cambridge group was already well situated for this kind of research, because they offer a service that helps dog owners make sure breeding doesn't produce puppies with troublesome genes.

They quickly spotted the gene driving PRA in English Shepherds, and then devised a commercial mouth-swab test that helps owners determine if their dog carries this DNA.

The gene in question is recessive, meaning that both the male and female dog involved in breeding must carry the gene before it can trigger PRA in a puppy.

But since dogs are very inbred, the odds of that happening are much higher than among species such as humans, the Cambridge team noted.

However, “for the price of a decent bag of dog food people can now have their English Shepherd tested for Progressive Retinal Atrophy prior to breeding," said senior study author and Cambridge veterinary researcher Dr. Cathryn Mellersh.

'It’s about prevention, rather than a cure, and it means a huge amount to the people who breed these dogs," she added. "They no longer need to worry about whether the puppies are going to be healthy or are going to develop this horrible disease in a few years’ time.”

The Cambridge group noted that PRA is closely related to an eye disease found in people called retinitis pigmentosa, so insights into human vision loss may arise from this research.

As for Shola, although she's no longer rescuing stranded hikers, her daughters are clear of PRA and just completed training with Mountain Rescue Search Dogs England. In fact, "one of them saved a man’s life three weeks ago," according to the Cambridge news release.

The study was published July 21 in the journal Genes.

More information

Find out more about PRA at Cornell University's Richard P. Riney Canine Health Center

SOURCE: University of Cambridge, news release, July 21, 2024

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