So that’s why Labradors get so fat! Scientists discover a genetic mutation in a quarter of all dogs that hard-wires them for obesity

With their friendly and outgoing nature, it’s no surprise that Labradors are some of the most popular dogs in the world.

But Labradors are known to gain weight, and now scientists think they know why.

A genetic mutation in a quarter of Labradors predisposes them to obesity, according to a study.

Around 25 per cent of Labradors face a “double whammy” of feeling hungry all the time and burning fewer calories due to a genetic quirk, research suggests.

Experts say this combination drives obesity and means dog owners must be particularly strict when feeding and exercising their dogs to keep them lean.

The mutation is in a gene called POMC, which plays a key role in hunger and energy use, and changes dogs’ behavior with food.

Researchers found that they don’t need to eat more to feel full, but they are hungrier between meals.

Additionally, dogs with the mutation were found to use about 25 percent less energy at rest than dogs without it.

As a result, they do not need to consume as many calories to maintain a healthy body weight.

In addition to Labradors, two-thirds of flat-coated retrievers also have the mutation, the team said.

Dr Eleanor Raffan, a researcher at the Department of Physiology, Development and Neuroscience at the University of Cambridge, who led the study, said: “We found that a mutation in the POMC gene appears to make dogs hungrier.”

«Affected dogs tend to overeat because they get hungry between meals more quickly than dogs without the mutation.

“All owners of Labradors and flat-coated retrievers should be careful about what they feed these highly food-motivated dogs to maintain a healthy weight.

“But dogs with this genetic mutation face a double whammy: Not only do they want to eat more, they also need fewer calories because they don’t burn them off as quickly.”

The study, published in Science Advances, found that the genetic mutation altered a pathway in the dogs’ brains associated with body weight regulation.

The mutation triggers a starvation signal that tells the body to increase food intake and conserve energy, even though this is unnecessary.

Dr Raffan said: “People are often rude to owners of fat dogs, blaming them for not properly managing their dogs’ diet and exercise.”

«But we have shown that Labradors with this genetic mutation search for food all the time, trying to increase their energy intake. “It is very difficult to keep these dogs thin, but it is possible.”

Researchers suggest that owners can distract their retrievers from this constant hunger by distributing each daily serving of food.

This can be done by using puzzle feeders or by spreading the food around the garden so it takes longer to eat.

In the study, 87 adult Labrador retrievers, all of a healthy weight or moderately overweight, participated in several tests, including the sausage-in-a-box test.

They were first given a can of dog food every 20 minutes until they decided not to eat anymore.

All the pets ate a lot of food, but the dogs with the genetic mutation did not eat more than those without it.

This showed that everyone feels full with a similar amount of food.

On another day, the dogs were fed a standard amount of breakfast and three hours later they were offered a sausage in a transparent plastic box and their behavior was recorded.

The dogs could see and smell the sausage, but they couldn’t eat it.

The researchers found that dogs with the mutation tried much harder to get the sausage out of the box than dogs without it, indicating greater hunger.

The dogs then slept in a special chamber that measured the gases they exhaled.

This revealed that animals with the mutation burned about 25 percent fewer calories than dogs without it.

The researchers say the new findings are consistent with reports of extreme hunger in humans with POMC mutations, who tend to become obese at a young age and develop a number of clinical problems as a result.