A Game-Changing DNA Test Aims to End Inherited Blindness in Dogs

Imagine your dog gradually losing its sight, bumping into furniture, and struggling with once-effortless tasks. For many pet parents, this heartbreaking scenario is all too real when their dog suffers from progressive retinal atrophy (PRA), a group of inherited diseases that leads to irreversible blindness. However, a groundbreaking DNA test developed through a collaboration between researchers at the University of Cambridge and Wisdom Panel is set to change this –  starting with English Shepherds.

The story began with Shola, a dedicated search-and-rescue English Shepherd, suddenly retired due to visual deterioration caused by PRA. Desperate for answers, her human, John Coombs, reached out to the University of Cambridge’s Department of Veterinary Medicine. Dr Cathryn Mellersh and Dr Katherine Stanbury, leading the research team, saw this as an opportunity to dig deeper into the genetic roots of the disease. Their mission? To identify the mutation responsible for PRA and create a reliable DNA test to detect it.

In collaboration with Wisdom Panel, which provided essential genotyping data, the research focused on sequencing the genomes of affected dogs. The breakthrough came when researchers collected DNA samples from six English Shepherds with PRA and 20 unaffected dogs. This modest sample size was enough to pinpoint the mutation responsible, paving the way for a diagnostic tool that can now identify carriers of the gene.

Dr Mellersh highlighted the challenge for dog parents: “An owner won’t necessarily notice their dog has got anything wrong with its eyes until it starts bumping into the furniture. Unlike humans who will speak up if their sight isn’t right, dogs just have to get on with things.”

The science may be complex, but the test itself is straightforward. For £48, a DNA sample – typically collected with a simple cheek swab – is screened for the gene linked to PRA. The results reveal whether a dog is clear, a carrier or at risk of developing the condition. Breeders can then make informed decisions to avoid producing puppies that will go blind.

For prospective pet parents, especially those considering an English Shepherd, this test could be a game-changer. Early detection allows for proactive management, potentially delaying blindness or preventing it entirely.

“Once the dog’s eyesight starts to fail there’s no treatment – they will end up totally blind,” says Dr Stanbury, emphasising the significance of the breakthrough. “Now we have a DNA test, there’s no reason why another English Shepherd Dog ever needs to be born with this form of PRA – it gives breeders a way of totally eliminating the disease.”

While this discovery is particularly beneficial for English Shepherds, the implications extend to other breeds and even to humans. PRA is an umbrella term for a group of inherited retinal diseases that cause the gradual deterioration of the retina, affecting over 100 breeds.

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Similar inherited conditions, such as retinitis pigmentosa in humans, also lead to blindness. The insights from this work could guide future treatments for such conditions, potentially leading to gene therapies. Wisdom Panel has already begun integrating the PRA test into its breed-specific genetic screening services, meaning more breeds will benefit as the technology evolves.

For those sceptical of yet another genetic test, it’s important to recognise that PRA is a serious problem. With no cure, prevention has always been the only effective strategy. Before this breakthrough, many dogs faced the sometimes scary reality of a slow descent into darkness. Now, this test could bring that nightmare to an end.

What makes this test particularly valuable is its breed-specific focus, which ensures greater accuracy and effectiveness. The research team believes that the knowledge gained from this study could eventually lead to treatments for both animals and humans with similar genetic conditions.

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By identifying carriers before they pass on the PRA mutation, breeders can make informed choices, ensuring healthier litters free from inherited blindness. Although this test is designed for English Shepherds, the research sets the stage for similar breakthroughs across other breeds.

But this isn’t just about breeding healthier dogs; it’s about giving parents peace of mind. With early genetic testing, dog parents can avoid the anguish of watching their pet slowly lose its sight, one step – or one collision with the coffee table – at a time.

For now, this breakthrough offers a glimmer of hope to countless dog parents and marks a significant leap forward in canine genetics. And who knows? The lessons learned here might one day lead to cures for similar conditions in humans. Until then, English Shepherds can look forward to a future where PRA is merely a thing of the past.