Flabby labradors can blame their genetics

On walks in the countryside, Leo the labrador will break into farmers’ fields to eat their cabbages. At home, he has to be locked out of the vegetable patch to stop him devouring carrots. And when he recently took part in a scientific study to see how much dog food he would consume before he felt full, the experiment had to be aborted for his safety when he refused to stop.

Now a study from Cambridge University has confirmed that he is not to blame for his seemingly insatiable appetite. Instead, he can point a paw at a rogue gene.

The research found that about a quarter of labrador retrievers feel hungry virtually all the time, and burn significantly fewer calories while they are resting, thanks to a single genetic mutation that tells their brain they are starving and makes them highly prone to obesity.

The mutation affects a gene called POMC. It is also estimated to occur in about twothirds of flat coated retrievers, but has not been seen in any other purebred dogs.

The POMC gene and the brain network it affects are similar in dogs and humans, and the new findings are consistent with reports of extreme hunger in people with POMC mutations, who tend to become obese when young.

The study, published in the journal Science Advances, was led by Dr Eleanor Raffan of Cambridge’s department of physiology, development and neuroscience.

“People are often rude about the owners of fat dogs, blaming them for not properly managing their dogs’ diet and exercise,” she 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 is possible that the mutation was once beneficial. “It is sending a ‘starvation signal’ that increases food drive and reduces energy consumption,” Raffan said. “The ancestors of both labrador and flat coated retrievers were St John’s water dogs, a type used by fishermen to retrieve their nets in the icy waters of Newfoundland from the 1600s onwards,” she said.

“They had a tough life, so a willingness to eat any scraps they could find might have helped them build up fat reserves to fuel their work and insulate them as they swam to retrieve fishing nets in the icy sea.”