Why labradors are prone to obesity

May 5, 2016

In a study published on Cell Metabolism has highlighted the fact that dogs are increasingly becoming obese much in keeping with their owners, with up to 60 per cent of dogs now overweight in some countries. While reading the study, it was shocking how man’s best friend is heading the way of human beings when it comes to weight issue.According to the study, variation also occurs more frequently in Labradors chosen as assistance dogs, and might explain why these canines seem more trainable with food rewards.Scientists have pinpointed a fault in the gene that should turn off hunger signals and makes food less of an obsession.The finding also suggests it is this food obsession that makes Labradors such good assistance dogs for those with disabilities.First author Dr Eleanor Raffan, from the University of Cambridge, said Labrador retrievers had topped obesity charts in studies and surveys in the US, UK and Australia over the past 30 years and had been shown to be more food motivated than other breeds.”As a vet, I see obese Labradors all the time and the breed have a real reputation for being food obsessed,” she said.”And whenever we see something that is more common in one breed than others, it is likely that genetics are to blame.”To test this belief the researchers initially analysed three genes known to be related to human obesity in 15 obese and 18 lean Labrador retrievers.From this they pinpointed a gene known as POMC, which is an important part of the mechanism that turns down background hunger when the body has plentiful energy reserves laid down as fat.

The team then further analysed 310 Labradors, including 81 assistance dogs.They found the Labradors were predisposed to have a deletion in the genetic code of the POMC gene which scrambles the end of the gene and hinders its ability to produce the neuropeptides associated with turning off hunger.Dr Raffan said this led to increased food motivation and weight seen in affected dogs.While not all dogs with the POMC deletion were obese, on average the POMC deletion was connected with a two kilogram weight gain.The veterinary surgeon said it was not possible to undertake the study and control for pet owner behaviour and feeding routines.However she said the findings were “more remarkable as we found the effect of this mutation despite the variability in how the dogs are managed by their owners”.”If owners are vigilant, it is possible to keep any dog skinny by carefully regulating diet and exercise.”But, our data illustrates that there is some hard-wired biology that drives dogs with the mutation to seek out food more than others.”She said the study showed the POMC deletion was more common among assistance dogs, occurring in 76 per cent of these dogs.In the general Labrador population the POMC deletion occurred in about 23 per cent of dogs.Dr Raffan said while it could be a “quirk” of the data it could also be a clue as to why these dogs were more trainable with food rewards.”A potential explanation is that the affected dogs are more willing to work for food than those without the mutation,” she said.”If so, they may be more likely to pass guide dog training since food rewards are commonly used to reward good behaviour there.

“Dr Raffan said the study also had implications for human obesity.”The dogs tell us general lessons about the importance of POMC in eating behaviour and obesity, importantly with relation to a part of the gene which is different in mice so has previously been hard to study.”We know POMC is important to humans and finding out more may lead to better treatment of human obesity.”Senior co-author Dr Giles Yeo adds: “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. Food is often used as a reward during training, and carrying this variant may make dogs more motivated to work for a titbit.“But it’s a double-edged sword carrying the variant may make them more trainable, but it also makes them susceptible to obesity. This is something owners will need to be aware of so they can actively manage their dog’s weight.” Professor Stephen O’Rahilly says: “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. So further research in these obese Labradors may not only help the wellbeing of companion animals but also have important lessons for human health.”The researchers believe that a better understanding of the mechanisms behind the POMC gene, which is also found in humans, might have implications for the health of both Labradors and human.

Contador Harrison