How a Labrador retriever’s genes might affect the dog’s obesity risk

Labrador retriever owners are likely familiar with how persistent their dogs can be in their quest for food, whether begging under the dinner table or stealing a snack left unattended. It’s no surprise, then, that Labs are among the most overweight dog breeds, along with golden retrievers, cocker spaniels and beagles.

Scientists have now identified multiple genes associated with obesity in Labradors, according to a March 6 study in Science.

The researchers had previously found that a form of a gene called POMC made Labs more prone to overeating. But “we could tell from our studies that the POMC mutation wasn’t the whole story,” says Eleanor Raffan, a veterinary surgeon and geneticist at the University of Cambridge.

In the new study, Raffan and her colleagues examined DNA samples from 241 British Labrador retrievers. The researchers also collected information including the dogs’ body fat mass, how much dogs begged for food, and how strictly their owners regulated their diet.

The researchers uncovered five genes potentially associated with obesity in the dogs. The strongest effect came from a gene called DENND1B — Labradors with a certain variant of this gene had around 8 percent more body fat than dogs without it. DENND1B, which affects how the brain’s responds to food, was also associated with higher body mass indexes in humans.

Knowing which genes were associated with obesity allowed Raffan and her colleagues to develop a risk scoring system, which helped calculate whether individual Labradors were at higher or lower risk of obesity based on their genetic profile.

“You can rank all of the individuals in the population based on whether they inherited a bunch of obesity-prone genes, or maybe they didn’t inherit many at all,” says Adam Boyko, a canine geneticist at Cornell University who was not involved with the study.

With this information, the researchers could see how high-risk and low-risk Labradors differed when it came to their relationships with food. Labradors at a high risk for obesity, for example, were more likely to beg and to be more driven toward finding food. And for Labradors that were more genetically predisposed to obesity, owners who were stricter about regulating their pets’ diet made all the difference.

“If you’re a high-risk dog and your owner is really strict with the management, you can be a perfectly healthy body weight,” Raffan says. “But if they’re pretty relaxed about the management, those are the dogs who get overweight.” She added that dogs with a lower genetic risk tended to stay at a fairly healthy weight, regardless of how their owner fed them.

So do you need a genetic test to determine whether your Labrador may be at risk for obesity? Probably not, says Raffan. If a dog seems like it would tip the scales if given the chance to plan its own diet, that could be a hint that their genes may be behind its drive for food. Trying to ration food for dogs that pack on the pounds could be a safe bet — though it’s often easier said than done. “To be disciplined about your dog’s food intake, it sounds straightforward, but it’s actually quite a tough job if you’ve got one of these massively food-motivated pets,” Raffan says.