Gene mutation explains why some dogs work for treats

3rd May 2016, Comments 0 comments

Scientists have discovered a genetic mutation that appears to make certain dogs, like Labrador retrievers, extra motivated by food and treats and also more likely to be obese, a study said Tuesday.

The report in the journal Cell Metabolism is the first to identify a gene associated with canine obesity.

"We've found something in about a quarter of pet Labradors that fits with a hardwired biological reason for the food-obsessed behavior reported by owners," said lead author Eleanor Raffan, a veterinary surgeon and geneticist at the University of Cambridge.

Researchers first identified the variation, which occurs in a gene called POMC, in a group of dogs that included 15 obese and 18 lean Labrador retrievers.

The obese dogs tended to have a section of DNA that was scrambled at the end of the gene, with the effect of hampering the dog's production of brain chemicals which tell the body it is no longer hungry after a meal.

A similar gene variant has been seen in some people who struggle with obesity.

"There are even some rare obese people who lack a very similar part of the POMC gene to that which is missing in the dogs," said senior author Stephen O'Rahilly, co-director of the Wellcome Trust-Medical Research Council Institute of Metabolic Science.

When scientists focused on a larger sample of 310 Labrador retrievers, they found that dogs with the POMC deletion were more likely to be chunky, begged for food more often, scavenged for scraps more and paid better attention at mealtime than those without the gene flaw.

Those with the POMC deletion -- which occurs in about 23 percent of Labrador retrievers -- tended to be 4.5 pounds (two kilograms) heavier, on average, than dogs without it, researchers said.

When the research team expanded their survey even further, to a sample of 411 dogs from 38 other breeds in Britain and the United States, the POMC deletion showed up again only in flat coat retrievers, which are related to Labrador retrievers.

Their "weight and behavior were similarly affected," said the report.

Among Labrador retrievers who work as assistance dogs, the team found the POMC deletion was quite common -- found in three out of four dogs studied.

"It was surprising," said Raffan.

"It's possible that these dogs are more food-motivated and therefore more likely to be selected for assistance-dog breeding programs, which historically train using food rewards."

For dog owners whose pets may like to munch too much, knowing that there may be a biological reason behind their dog's begging could help.

"The behavior of dogs carrying this mutation is different," said Raffan.

"You can keep a dog with this mutation slim, but you have to be a lot more on-the-ball -- you have to be more rigorous about portion control, and you have to be more resistant to your dog giving you the big brown eyes."

© 2016 AFP

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