Dog DNA tests are sending us down the path to the perfect pupper

Getty Images / alvarez / Emmanuelle Bonzami / EyeEm / WIRED In the dog DNA business, things don’t get much busier than Crufts. When the doors to the world’s biggest dog show lurched open on Thursday, March 7, nestled amongst stalls selling dog portraits, dog nerf guns and dog bandanas pet owners found a handful of firms ready to sell take-home DNA tests that let them peer into their pet’s genetic past.

Visitors to the DNA-testing stands are presented with leaflets denoting the dizzying number of things that genetic tests can tell owners about their dogs. There are the obvious ones – a dog’s precise breed, and those of its ancestors as well its likelihood of developing a range of health conditions. But there are other details waiting to be uncovered within a dog’s genome: whether it will grow a moustache and bushy eyebrows, for example, or the identity of its long-lost uncle.

For many of the owners funneling past the stalls of companies with names like Wisdom Panel, Laboklin and Animal DNA Diagnostics, the genetic tests will seem like little more than a throwaway novelty. But in the idiosyncratic world of professional dog breeding, genetic tests are becoming an indispensable tool. And elsewhere researchers are discovering clues in dog DNA that could – quite literally – reshape some of our best-loved breeds.

As advances in DNA testing slowly uncover the genetics underpinning the health, behaviour and look of our favourite breeds, researchers, dog DNA firms and breeders are finding themselves circling around an intriguing question. Can DNA tests help us build a better dog?

For championship dog judge and hobbyist breeder Vicky Collins-Nattrass, there is something about a bulldog’s eyes that you can’t find anywhere else in the canine world. A true bulldog has a softness to their eyes, she says. When you look into them, they look back at you with a reassuring warmth.

But Collins-Nattrass – who has bred five generations of bulldogs – is concerned that not all bulldogs have the same warmth to their eyes. The problem, she says, is to do a vogue for new bulldog coat colours. "People are nowadays are obsessed with having colours that aren’t the recognised colours and the weirder they are the better they like them,” she says.

According to their breed standards – a description of the ideal characteristics of a purebred dog that judges used to identify prizewinning pups – bulldogs come in a limited range of colours including brindle, red, fawn, fallow and white. But some rogue breeders, encouraged along by DNA tests that help them narrow down the colour genes their dogs are carrying, are breeding bulldogs in black, merle, chocolate, blue or lilac, because the unusual dogs can command a higher price.

Some of these novelty-coated bulldogs also have unusual eye colours – blues or greys instead of deep browns. So when Collins-Nattrass looks into the eyes of novelty-coated bulldogs, she doesn’t see the same warmth and depth that she has come to identify with the breed. Sometimes, she doesn’t see a bulldog at all.

Controversial coat colours are one thing, but beneath the surface some bulldogs are carrying a genetic time bomb with an impact far beyond aesthetics. Bulldogs, along with pugs, chihuahuas, pekingese, shih tzus and a handful of other breeds often suffer from a conditions called brachycephalic obstructive airway syndrome (BOAS). Dogs with BOAS have obstructed airways, making it hard for them to exercise or cool themselves, and leaving them susceptible to collapsed airways. The cause of their condition is closely tied to the bulldog’s genetics – and its unusually short head.

Over the last century-and-a-half, BOAS has become much more common. And humans are to blame. Dogs are descended from wolves that were domesticated by humans at least 15,000 years ago – although the exact dating of canine domestication is hotly disputed among researchers. Of course, a modern bulldog doesn’t bear much resemblance to its lean, toothy, lupine forebears.

The reason for that is that bulldogs were bred for a very specific purpose – to help farmers control bulls and other livestock. For this job, breeders favoured dogs that were stocky and muscular. They also selected dogs that had short, powerful jaws that could nip bulls without doing too much damage. Over time, breeders also started favouring more aggressive dogs that could be used for bull baiting – a sport where dogs were forced to fight bulls.

But it was the banning of bull baiting in 1835 that sent bulldogs careening towards their distinctive modern-day physiognomy. No longer seen as working dogs, bulldogs were bred for their physical cuteness – and this placed a new emphasis on shorter faces, stockier bodies and bulging eyes. The new trend for smaller, cuter, bulldogs led to the creation of a whole new breed – the French Bulldog – which is now the UK’s most popular purebred dog. Over 8,000 French Bulldog puppies were registered in the first quarter of 2018 alone – and that’s only dogs registered by the Kennel Club, the organisation behind that oversees purebred dogs in the UK and puts on Crufts.

The vogue for shorter faces led to skyrocketing rates of BOAS – as dogs with shorter faces have tightly constrained upper airways. Rates of BOAS among brachycephalic (short-headed) breeds may be as high as 15-20 per cent among purebreds, although finding the exact prevalence of the condition is tricky because concerned owners are more likely to seek a diagnosis. In other words, selective breeding is leading bulldogs down a genetic cul-de-sac which may be increasing their risk of other conditions, including kidney stones and hip problems. But DNA tests could offer a way out of this bind.

David Sargan, a researcher at the University of Cambridge’s department of veterinary medicine, is looking for the genes behind BOAS. He’s already on the way to understanding how a dog’s genetic makeup determines its likelihood of developing the condition, and estimates that BOAS is half determined by genetics and half by a dog’s environment.

Sargan hopes that if he can develop a genetic test for BOAS, it might help breeders steer away from dogs predisposed to the condition. But there’s a problem. Dogs that are less likely to develop BOAS may also be less likely to fit the breed standards that determine the ideal size and shape of the dog.

There is some hope, however. Although the breed standards – which are devised and owned by the Kennel Club – sometimes date back over 100 years, they are slowly changing to take into account health conditions. Sargan advised on the most recent changes to the breed standards, in 2010, which started to place less emphasis on flatter faces. While earlier bulldog standards said that the breed should have a large “head” this has been moderating down to “relatively large” and now bulldogs can get away with having a “moderately short” distance from the tip of their nose to the back of their heads.

“Until the breed clubs started to see that they really had a problem, we weren’t seeing progress and there was quite a lot of evidence that skull shape changed to be even shorter and flatter over the last 100 years – until about 10 years ago,” Sargan says.

Companies that specialise in dog DNA tests are also racing to pinpoint the genetic triggers behind certain characteristics. One of those firms – Boston-based startup Embark – scours more than 250,000 genetic markers to work everything from the likelihood that your dog will have a moustache to whether it’ll shed a lot of hair or not and how closely it’s related to another dog.

But Embark isn’t stopping at physical attributes. Each breed has its own distinct personality, which suggests that there are genetic triggers for different behavioural characteristics, too. “We definitely would like to explore behavioural genetics,” says Alison Ruhe, Embark’s director of breed organisation. “Clearly dogs have distinctive behaviours that have been selected for through breeding.”

And while geneticists like Sargan have to scour breed shows and kennels in the search of dogs to test, Ruhe has access to a huge number of pet owners who will bring their dog’s DNA right to her doorstep. She frequently compares Embark’s approach with that of 23andMe – the US firm responsible for turning consumer DNA tests into a huge industry.

By asking dog owners questions about their dogs, and comparing those responses with genetic markers, Ruhe is hoping she can start to tease out the genetic basis for attributes like playfulness, or docility. In October last year, Embark released a study of more than 6,000 dogs that identified the gene behind the icy blue eyes of Siberian Huskies. According to the firm, it was the largest canine genome-wide association study to date.

For Ruhe, purebred dogs provide the perfect place to identify genetic triggers. While dogs with a mixed ancestry have a lot of genetic “noise” the relatively limited gene pools of purebred dogs make it easier to spot unusual genes that might linked to different characteristics. “Purebred dogs are a marvelous model for genetics,” she says.

With enough genetic data, […]

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