Eleanor Raffan is a veterinary surgeon at the University of Cambridge, and, not so long ago, she noticed that many of the Labrador retrievers she saw in her clinic had one striking physical attribute in common: Good lord, were they fat.
Raffan also happens to be a geneticist, and her curiosity was piqued by the obese Labradors that kept showing up in her practice. “When I speak to their owners, everybody says, ‘My dog is really obsessed with food,’” she told LiveScience. “And whenever we see something that is more common in one breed of dog than another, genetics are implicated as a possible factor.” And so she decided to put her hunch to the test, embarking on a small initial study examining the genetic makeup of 33 Labrador retrievers, about half of which were very fat and half of which were not. According to her findings, the obese dogs in the study were more likely to carry a mutant form of a gene known as POMC, which is associated with obesity in a rather fascinating way.
Babies with mutated versions of this gene, for example, are often born at a normal weight, but are insatiably hungry — and so they are more likely to become obese by the time they reach their first birthday. In humans with this particular mutation, it’s like their hunger doesn’t have an “off” switch, and Raffan believes this is what’s happening in these dogs, too.
Raffan followed up that first study with another one, which found similar results but on a larger scale, reports LiveScience:
After studying more than 700 additional Labs, they found the POMC gene variation in about 23 percent of the dogs — approximately 1 in 4 Labradors is likely to carry this variant, the scientists noted. Not all of the Labradors with the “scrambled” gene were obese, but Raffan and her colleagues found that those dogs with the gene were more likely to beg and scavenge for food, according to surveys provided by their owners.
Alas, the genetics piece of the Labrador obesity puzzle doesn’t necessarily mean humans are off the hook for the overabundance of fat Labs. As New Scientist points out, these dogs are often trained as service animals, and that training typically involves lots of goading along with the use of treats. “Because food is often used as a reward during training,” explains writer Alexander Bates, “we may have been inadvertently selecting and breeding Labradors that have this gene variant, which makes them especially interested in food.” Maybe, then, this scrambled gene is part of the reason why Labs are so highly trainable.
This research is interesting for anyone who happens to own an always-hungry Lab, but Bates nods to a more wide-ranging benefit. The POMC mutation has often been studied in mice or rats, which isn’t a perfect way to study it, as the gene in these animals behaves differently from the way it does in humans. But POMC in Labs looks and acts more similarly to the way it does in humans, according to Raffan’s study, so this could lead to better understanding of how to help people (and dogs) with this mutation. Meanwhile, perhaps it’s time for Biggest Loser: Dog Edition. Then again, maybe not.