Eating is second nature to Labrador retrievers and scientists say this could be because of their genes.

A past study has concluded that online images of fat dogs predispose dog owners to think that obese dogs are better. In the said study, Labrador retrievers are found to weigh more than the ideal number compared with other breeds.

Obesity in dogs is fairly common, with numbers reaching 34 to 59 percent. While it is believed that lack of exercise and high calorie diet are to blame, new research shows that Labradors are genetically predisposed to become fatter.

Researchers led by University of Cambridge veterinary surgeon and geneticist Eleanor Raffan investigated 18 lean and 15 obese Labradors and three genes that play a role in human obesity.

Raffan, who has previously studied human obesity, proposed that the genes could somewhat be related to canine obesity as well.

The current study revealed that Labradors have a POMC gene modification, which hinders production of beta-endorphin and beta-MSH neuropeptides - genes that are responsible for switching off hunger after a meal.

Senior author and co-director of Wellcome Trust-Medical Research Council Institute of Metabolic Science Stephen O'Rahilly said that the deletion seems to be exclusive to Labradors and its relative flat-coat retrievers. Moreover, this factor is highly associated with dogs' increased food-motivated behavior. O'Rahilly also said that a portion of POMC gene is also absent in some obese humans.

To further study the correlation of POMC deletion to food-motivation behavior of the dogs, the team studied 310 Labradors. They found that while not all that have genetic modifications are obese, the dogs with the deleted gene are significantly fatter by about 4.5 pounds than other dogs without the modification.

An owner survey also suggested that dogs without the POMC gene exhibit more food-motivated behaviors, such as mealtime aggressiveness, food begging, and food scrap scavenging.

The study also revealed that 23 percent of 411 Labrador retrievers from the U.S. and the UK have the POMC gene deletion.

Labrador Assistance Dogs

A cohort study also found that 76 percent of Labradors used as assistance dogs have the POMC gene deletion, which is why they are easily trained when given food treats as their reward.

Then is effective assistance dog training due to the existing gene mutation?

The researchers said that this can only be proven if the mutation is observed in puppies and used as a qualifier for assistance dog training.

"Labradors make particularly successful working and pet dogs because they are loyal, intelligent and eager to please, but importantly, they are also relatively easy to train," said senior co-author Giles Yeo. "Food is often used as a reward during training, and carrying this variant may make dogs more motivated to work for a titbit."

Food-Motivated Behavior

Raffan said dogs with the mutation have different behaviors. Being able to keep them slim is a tedious job. Owners have to be wary of portion control and have to fight the urge to give in to the dogs' big begging eyes.

"If you keep a really food-motivated Labrador slim, you should give yourself a pat on the back, because it's much harder for you than it is for someone with a less food-motivated dog," said Raffan.

The study, O'Rahilly said, is not only beneficial for the well-being of dogs but also offers insights about human health.

The study was published in Cell Metabolism on May 3.

Photo: Jem Stone | Flickr

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