July 2024

Progressive retinal atrophy (PRA) is a group of inherited diseases that causes progressive degeneration of the light sensitive cells at the back of the eye. Dogs with PRA have normal sight at birth, but by the age of four or five they will be totally blind. There is no treatment. Now a team led by the University of Cambridge has identified the genetic mutation that causes PRA in English Shepherd Dogs, and developed a DNA test for it. By identifying dogs carrying the disease before their eyesight starts to fail, this provides a tool to guide breeding decisions so the disease is not passed on to puppies. Owners usually don’t realise their dog has PRA until it is middle-aged, by which time it might have bred, and passed on the faulty gene to its puppies. This has made it a difficult disease to control. The new discovery means that progressive retinal atrophy can now be completely eliminated from the English Shepherd Dog population very quickly. The results are published today in the journal Genes. “Once the dog’s eyesight starts to fail there’s no treatment – it will end up totally blind,” said Katherine Stanbury, a researcher in the University of Cambridge’s Department of Veterinary Medicine and first author of the report. She added: “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.” The genetic mutation identified by the team is recessive, which means it only causes blindness if the English Shephard Dog inherits two copies of it. If the dog only has one copy this makes it a carrier – it will not develop PRA but can pass the mutation on to its puppies. If two carriers are bred together, about one in four of the puppies will be affected with PRA. Dogs breeds are very inbred, so many individuals are related – giving them a much higher chance of being affected by recessive diseases than humans. The team began the research after being contacted by a distraught owner of an English Shepherd Dog that had been recently diagnosed with PRA. The dog had been working as a search and rescue dog but had to retire due to visual deterioration that has resulted in total blindness. The researchers put out a call for DNA samples from other owners or breeders of this breed, and received samples from six English Shepherds with PRA and twenty without it. This was enough for them to pinpoint the genetic mutation responsible for PRA using whole genome sequencing. The team offers a commercial canine genetic testing service providing DNA tests to dog breeders to help them avoid breeding dogs that will develop inherited diseases. As part of this they will now offer a DNA test for Progressive Retinal Atrophy in English Shepherds. Anyone can buy a testing kit, costing just £48, to take a swab from inside their dog’s mouth and send it back for testing. “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,” said Dr Cathryn Mellersh in the University of Cambridge’s Department of Veterinary Medicine, senior author of the report. She added: “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. It’s about prevention, rather than a cure, and it means a huge amount to the people who breed these dogs. 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 English Shepherd is a breed of herding dog popular in the United States and is closely related to the Border Collie. The new discovery is the thirty-third genetic mutation causing an inherited disease in dogs that the team has found – twenty-three of which cause eye diseases. They say that the health and wellbeing of many dogs has been compromised because of how they have been bred by humans. PRA occurs in many dog breeds including the English Shepherd Dog. And it is similar to a disease called retinitis pigmentosa in humans, which also causes blindness. The researchers say that their work with dogs could shed light on the human version of the disease and potentially identify targets for gene therapy in the future. Read More

Do people choose dogs that look like them, or do dogs start to look more like their owners over time? (Image credit: Nevena1987 via Getty Images) Visit any dog park, and you’re bound to see matching pairs of dogs and humans. But do dogs really tend to look like their owners? And, if so, what’s responsible for this resemblance?  “Whilst not a universal phenomenon amongst all owners and dogs, there is some evidence that purebred dogs and owners tend to resemble each other at some level,” Katrina Holland, a research officer on the human behavior team at Dogs Trust, an animal welfare charity in the U.K., told Live Science in an email.  Several studies have found that people can successfully match pictures of purebred dogs with pictures of their owners at levels above random chance. In one study, participants were able to match dogs with their owners regardless of whether they were told to choose the real dog-owner pairs or just choose pairs that looked alike. This finding suggests that it’s physical appearance, and not some other element, that people are using to make these judgments. Certain aspects of physical appearance are more important than others. Facial features, especially the eyes, are more integral to the perception of resemblance than qualities such as size, hairstyle and physical fitness, a different 2015 study found. When a researcher showed participants real and fake dog-owner pairs while masking different parts of the dogs’ and owners’ facial features, the participants were equally successful at matching when they saw only the eye region as when they saw the full face or the face with the mouth covered. But when they masked the eye region, the participants’ success rate dropped to 50-50. So if it’s true that dogs tend to look like their owners, why is this? Do we choose dogs that look like us, or do our dogs start to look more like us over time? Related: Could dogs survive without humans? Research suggests it’s probably the former, Holland said. Get the world’s most fascinating discoveries delivered straight to your inbox. For example, a 2004 study found that how long a person had owned their dog wasn’t correlated with their resemblance; participants were just as successful at picking out the dog-owner pairs regardless of how long those pairs had been together. That suggests that people are choosing dogs that look like them at the outset. It’s not just appearance; sometimes dogs’ “Big Five” personality dimensions match those of their owners. (Image credit: Digital Vision. via Getty Images) One hypothesis is that people tend to seek out people, including mates, who look like them, Holland said. Researchers have suggested that the same thing happens when people choose their pets.  “Alternatively, it may be that we prefer dogs who look somewhat similar to us due to the ‘mere exposure effect,’ in which people prefer familiar items (i.e., their own faces, seen frequently through mirror exposure) over those they have not seen before or seen less often,” Holland said.  A familiar example of the mere exposure effect happens with music: A song that you didn’t like much the first time you heard it becomes irresistible after it’s on the radio all summer. People see their own face constantly, so that repeated exposure leads them to prefer faces that look like their own, including in dogs. It’s not just appearance, either. “Findings from a recent study indicate that dogs and their owners resemble each other in the ‘Big Five‘ personality dimensions”: extraversion, agreeableness, openness, conscientiousness and neuroticism, Holland said. These findings also support the idea that we select pets that are similar to us, she said — not just those that look like us, but those that act like us, too.  Of course, a dog’s similarity to us isn’t the only thing to think about when choosing a pet. “Taking your time to fully consider all aspects of dog ownership and being prepared will help set you up for a lifelong, successful relationship with your new dog, Holland said.” But after those considerations, there’s nothing wrong with picking out a cute canine twin to hit the dog park with. Ashley Hamer is a contributing writer for Live Science who has written about everything from space and quantum physics to health and psychology. She’s the host of the podcast Taboo Science and the former host of Curiosity Daily from Discovery. She has also written for the YouTube channels SciShow and It’s Okay to Be Smart. With a master’s degree in jazz saxophone from the University of North Texas, Ashley has an unconventional background that gives her science writing a unique perspective and an outsider’s point of view. Most Popular Read More