• Posted March 7, 2024

Many Labradors Become Obese and Research Shows Why

Nearly a quarter of Labrador retrievers are more likely to be obese due to a genetic "double-whammy,"a new study finds.

This gene mutation causes Labradors to both feel hungry all the time and also burn fewer calories, British researchers report.

The mutation involves a gene called POMC, which plays a critical role in hunger and energy use among Labs.

About 25% of Labradors and 66% of flat-coated retriever dogs have this POMC mutation, which causes increased interest in food, researchers said.

Specifically, it makes them hungrier in between meals, even though they don't need to eat more to feel full at mealtime.

"We found that a mutation in the POMC gene seems to make dogs hungrier. Affected dogs tend to overeat because they get hungry between meals more quickly than dogs without the mutation,"said study author Eleanor Raffan, a researcher in the University of Cambridge's Department of Physiology, Development and Neuroscience.

Dogs with the POMC mutation also tend to burn about 25% less energy at rest than dogs without it, the researchers added. That means they should consume fewer calories to maintain a healthy body weight.

"Dogs with this genetic mutation face a double whammy: They not only want to eat more, but also need fewer calories because they're not burning them off as fast,"Raffan said in a university news release.

The mutation in the POMC gene causes dogs to not produce two chemical messengers in their brain, beta-melanocyte stimulating hormone (β-MSH) and beta-endorphin, that are important in determining hunger and moderating energy use, researchers said. 

The new study involved 87 adult Labradors, all at a healthy weight or slightly overweight.

First, the dogs were given a can of dog food every 20 minutes until they chose not to eat any more.

All the Labs ate huge amounts of food, but the dogs with the POMC mutation didn't eat more than those without it -- an indication that they all feel full with a similar amount of food.

Next, researchers put the Labs through the "sausage in a box"test.

On a different day, the dogs were fed a standard amount of breakfast. Exactly three hours later, they were offered a sausage in a box made of clear plastic and a perforated lid, so the Labs could see and smell the sausage but couldn't eat it.

Labradors with the POMC mutation tried significantly harder to get the sausage out of the box, researchers found. That indicates those dogs were much more hungry between meals.

Lastly, the Labradors slept in a special chamber that captured the gases they breathe out, which can be used to measure body metabolism. Dogs with the POMC mutation burned around 25% fewer calories while resting, compared to other dogs.

"People are often rude about the owners of fat dogs, blaming them for not properly managing their dogs' diet and exercise,"Raffan said. "But we've shown that Labradors with this genetic mutation are looking for food all the time, trying to increase their energy intake. It's very difficult to keep these dogs slim, but it can be done."

One way it can be done? Some research has suggested that probiotics can help overweight dogs shed pounds.

These findings could be helpful for humans as well, given that the brain pathways affected by the POMC mutation are similar in dogs and humans, researchers said.

Humans with POMC mutations tend to experience extreme hunger and become obese at an earlier age, researchers said in background notes.

Drugs currently in development for humans target these pathways to treat obesity, low sexual desire and certain skin conditions, researchers said.

The new study was published March 6 in the journal Science Advances.

More information

The National Institutes of Health has more about POMC deficiency in humans.

SOURCE: University of Cambridge, news release, March 6, 2024