When it comes to greedy dogs, Labradors take the cake. Now researchers have shed light on why the breed is prone to a portion form.
Scientists previously revealed a mutation in a gene called POMC (proopiomelanocortin) predisposes dogs to obesity. The genetic variant is found in about a quarter of Labrador retrievers and two-thirds of flat-coated retrievers, with the effect slightly greater in the former.
Now two explanations for the association have emerged: not only are dogs with the mutation hungrier between meals, but they burn fewer calories when resting.
“This means that these dogs have a double whammy,” said Dr Eleanor Raffan, from the University of Cambridge, who led the study.
But obesity in dogs is not a fait accompli.
“What we know is that there [are] loads of owners who manage their dogs very carefully, and do manage to keep them slim – but they do it by putting in a lot of effort,” said Raffan.
Write in the journal Science AdvancesRaffan and colleagues describe how their first test involved 36 adult labradors who either carried one copy of the POMC mutation, two copies, or no mutation at all.
The dogs, who were all on a standard diet, were given breakfast and three hours later were shown a transparent box with a perforated lid into which a researcher had placed a sausage. The dogs were then allowed to approach the box.
The researchers found that dogs with the POMC mutation spent much less time resting or exploring the room, and more time getting to the piece, than those without.
“The dogs with the mutation were just much more fixated on the sausage,” Raffan said, adding that this suggests they were hungrier.
But a subsequent test with 24 labradors with either one or no copies of the mutation highlighted that it wasn’t because they felt less full immediately after eating: regardless of their genetics, the dogs voluntarily ate a similarly enormous amount of wet dog food consumed – about 2 kg on average – when a can is offered every 20 minutes.
The team also analyzed the calories burned by 19 adult flat-coated retrievers when they were at rest by measuring their oxygen consumption and carbon dioxide production in a specially adapted kennel.
The results revealed that dogs with two copies of the mutation burned about 25% fewer calories than those with no copies—enough, the researchers say, to significantly reduce how much food they needed to maintain a healthy body weight.
While the situation in humans is more complex, Raffan said the study is a powerful illustration of how genes can influence behavior around food.
“It’s a message about obesity not being a choice,” she said. “It’s a reflection of an underlying urge to eat, which is driven by a combination of your genes and your environment.”
