If clients with Labradors tell you their pets beg for food a lot, their observations may be astute. At least, that’s what a new study suggests.

Researchers in the United Kingdom and Sweden have linked a gene alteration specifically found in Labradors and related flat coat retrievers to greater food-motivated behavior, describing the first gene associated with canine obesity. The variation also occurs more frequently in Labradors chosen as assistance dogs.

The study was published May 3 in Cell Metabolism.

Starting with an initial cohort of 15 obese and 18 lean Labrador retrievers, the researchers selected three obesity-related genes to examine, all of which were known to affect weight in humans. This first analysis turned up a variation in a gene called POMC.

In more of the obese dogs, a section of DNA was scrambled at the end of the gene. The deletion is predicted to hinder a dog's ability to produce the neuropeptides β-MSH and β-Endorphin, which are usually involved in switching off hunger after a meal.

In a larger sample of 310 Labrador retrievers, the researchers discovered a host of canine behaviors associated with the POMC deletion. Not all Labs with the DNA variation were obese (and some were obese without having the mutation), but in general the deletion was associated with greater weight.

Additionally, according to an owner survey, affected dogs were more food-motivated—they begged their owners for food more frequently, paid more attention at mealtimes, and scavenged for scraps more often.

On average, the POMC deletion was associated with a 4.6 pound weight increase.

"We've found something in about a quarter of pet Labradors that fits with a hardwired biological reason for the food-obsessed behavior reported by owners," said Eleanor Raffan, PhD, from the University of Cambridge and one of the study authors.

The researchers found that the POMC deletion occurs in roughly 23% of Labrador retrievers overall, based on further sampling of 411 dogs from the United Kingdom and the United States. Of 38 other breeds, the deletion only showed up again in flat coat retrievers, related to Labrador retrievers, and weight and behavior were similarly affected.

Notably, the POMC deletion was markedly more common in the 81 assistance Labrador retrievers included in the study, occurring in 76% of these dogs.

"We had no initial reason to believe that the assistance dogs would be a different cohort," says Raffan. "It was surprising. It's possible that these dogs are more food-motivated and therefore more likely to be selected for assistance-dog breeding programs, which historically train using food rewards."

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