Labrador Retrievers Are More Prone to Obesity Than Other Breeds

August 24, 2016
Kristi Rosa

A recent study has shown that a gene mutation associated with weight and food motivation has been found specifically in Labrador and flat coat retrievers, occurring even more frequently in Labradors who are used as assistance dogs.

Owners of Labrador retrievers always talk about their pets’ infatuation with food, but a recent study has shown that the reason for that may be found within their genetics. A recent study published in Cell Metabolism, found that a gene mutation associated with weight and food motivated behavior has been found specifically in Labrador and flat coat retrievers. Additionally, the study showed that the genetic mutation occurs even more frequently in Labradors who are used as assistance dogs, which could also explain why food rewards are so effective when it comes to their training, according to the press release.

The prevalence of dog obesity ranges between 34% and 59% in developed countries and canine obesity has been associated with a reduced lifespan as well as specific morbidities that mirror obesity in humans. Both humans and dogs experience similar implicated environmental factors such as having more high-calorie food readily available and partaking in less exercise, according to the study. However, environmental factors are not the only thing at work here. According to the study, “…despite the fact that dog owners control their pets’ diet and exercise, susceptibility to obesity varies between dog breeds, which suggests the influence of genetic factors.”

Labrador retrievers, for instance, tend to be more motivated by food and have a higher prevalence of obesity than other dog breeds, according to study. Dr. Eleanor Raffan, PhD, veterinary surgeon and geneticist at the University of Cambridge, said, “Whenever there’s something more common in one breed than another, we think genetics are involved.” Dr. Raffan has also studied human obesity throughout her career, previous to this study.

Dr. Raffan and her colleagues examined, in a cohort of 15 obese and 18 lean Labrador retrievers, three obesity genes that are also known to affect weight in humans: melanocortin-4 receptor (MC4R), agouti-related peptide (AGRP), and POMC. The first analysis found that the POMC gene found in more of the obese dogs was mutated. The POMC mutation disrupts the production of β-MSH and β-Endorphin neuropeptides that “are usually involved in switching off hunger after a meal,” according to the press release.

Variations in the POMC gene are associated with body weight differences when it comes to humans as well. Stephen O’Rahilly, co-director of the Wellcome Trust-Medical Research Council Institute of Metabolic Science and senior author of the study commented, “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.”

Dr. Raffan and colleagues found out even more about the POMC mutation and how it influences canine behaviors when they studied a larger cohort of 310 Labrador retrievers. Even though some of the Labradors analyzed were obese without having the POMC mutation, the mutation was associated with greater weight. Additionally, an owner survey showed that dogs with the POMC mutation “were more food-motivated—they begged their owners for food more frequently, paid more attention at mealtimes, and scavenged for scraps more often,” according to the press release.

When speaking of the implications of these findings, Dr. Raffan said, “We’ve found something in about a quarter of pet Labradors that fits with the hardwired biological reason for the food-obsessed behavior reported by owners. There are plenty of food-motivated dogs in the cohort who don’t have a mutation, but there’s still quite a striking effect.”

When Dr. Raffan and her colleagues took another sampling from 411 dogs from the United Kingdom and the United States, they found that the POMC mutation occurred in about 23% of Labrador retrievers. Thirty-eight other breeds were included in this sampling and Labrador and flat coat retrievers were the only ones to show this POMC mutation.

Furthermore, the mutated POMC gene was found to be more common in the Labrador retrievers that were also assistance dogs. Of the 81 Labrador assistance dogs included in the study, 76% of the dogs had POMC mutation.

When speaking of this unexpected finding, Dr. Raffan commented, “We had no initial reason to believe that the assistance dogs would be a different cohort. It was surprising. 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.”

According to the study, the two main factors that are taken into consideration when choosing assistance dogs are temperament and trainability. The researchers hypothesize that dogs who have the POMC mutation are more likely to be chosen as assistance dogs; however, Dr. Raffan cautioned, “We haven’t yet looked at puppies and asked if they’re more likely to qualify as an assistance dog if they have a mutation.”

The results of the study provide other researchers with more knowledge on how biological factors can influence the weight of canines. Dr. Raffan said, “The behavior of dogs carrying this mutation is different. 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. 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.”

Dr. Raffan and her colleagues feel that conducting further research related to obesity in Labrador retrievers can be beneficial in understanding human obesity as well. Using their findings regarding the mutation of POMC, Dr. Raffan and her colleagues are going to investigate potential therapeutic implications for humans with obesity, according to the press release.