Labrador retriever fanatics prize the dogs for their friendly, happy-go-lucky personalities--but they struggle with the sad fact that their chosen breed is remarkably susceptible to obesity. Nearly 60% of labs are overweight, according to the Association for Pet Obesity Prevention.
Scientists at the University of Cambridge may have discovered the culprit behind all those fat labs. They found that a particular variant in a gene called POMC is strongly associated with appetite and obesity in labs and flat-coated retrievers. Nearly one-quarter of labs are believed to have the variant, according to a study the researchers published in a recent edition of the journal Cell Metabolism.
The POMC gene regulates how the brain recognizes hunger and the feeling of being full after a meal. Labs are known for being easy to train--but that might be because their owners usually use treats as rewards. The gene variant only makes the dogs more motivated to please their owners in return for food. "People who live with Labradors often say they are obsessed by food, and that would fit with what we know about this genetic change," said first author Eleanor Raffan in a press release.
Raffan and her co-authors started with a group of 15 obese and 18 normal-weight labs. After analyzing three obesity-related genes in all the dogs, they discovered that a segment of DNA was scrambled in POMC. That impeded the body’s ability to produce two proteins that normally switch off the hunger signal, according to a press release from Cell Press.
When they expanded the study to include 310 labs, the scientists discovered that all the dogs with the POMC variant were more food-motivated than those who didn’t have it--meaning they were more likely to beg for table scraps or scavenge for crumbs after the family left the table. Not all of the dogs carrying the abnormal gene were obese, but they were heavier by about 2 kg on average, according to Cell Press.
People also carry the POMC gene, making this latest finding in dogs potentially translatable to ongoing efforts to curb rising obesity rates. "Common genetic variants affecting the POMC gene are associated with human body weight and there are even some rare obese people who lack a very similar part of the POMC gene to the one that is missing in the dogs,” said senior author Stephen O'Rahilly, co-director of the Wellcome Trust-Medical Research Council Institute of Metabolic Science at the University of Cambridge, in the release. “So further research in these obese Labradors may not only help the wellbeing of companion animals but also have important lessons for human health."