If you own a Labrador Retriever, you know they’ll do just about anything for food. But that relentless appetite could be a genetic fluke, an international team of scientists has discovered.
Labradors with a mutation in a gene called POMC have a bigger appetite and are more likely to be obese, according to genetic research. This mutation, previously only seen in obese humans, may also explain why Labs are more easily trained as assistance dogs.
A big appetite doesn’t bode well for Labradors – they have the highest documented obesity prevalence of any dog breed. And just like in humans, their obesity comes with a reduced lifespan and a suite of other health problems.
“Whenever there’s something more common in one breed than another, we think genetics are involved,” said study author Eleanor Raffan.
In search of a cause for the Labrador’s appetite, her team examined 15 obese and 18 lean Labradors for genes known to affect body weight in humans. The researchers discovered a mutated version of one – the POMC gene, missing a 14-letter sequence – was more common in obesity-prone dogs.
Out of 411 UK and US dogs studied, around 23% of Labradors had the POMC deletion. And aside from the Labrador’s close cousin, the Flat-Coated Retriever, the scientists did not find the mutation in other breeds.
POMC encodes two hormones called β-MSH and β-endorphin, which when released in humans lock on to receptors in the brain which switch off hunger signals. A deficiency of these hormones caused by the mutation, the authors argue, could lead to more appetite and weight gain in dogs.
Genetics couldn’t be blamed for every chubby Labrador involved in the study – some were obese without the POMC deletion and some were slim despite it – but on average, Labradors with the mutation were two kilograms heavier.
And a survey of the owners revealed Labradors with the mutation beg for food and scavenge for scraps more often, and pay closer attention to mealtimes.
The POMC deletion was also far more common in the 81 assistance Labradors included in the study, occurring in 76% of these dogs.
The authors suggest the POMC mutation – and a bigger appetite – makes dogs more “trainable”, as positive reinforcement with treats is a common puppy training method. But the researchers are yet to investigate how POMC deletion affects puppy behaviour.
Aside from being the first genetic link to canine obesity, the team hopes their discovery will lead to new therapeutic approaches for treating the condition in dogs.
Meanwhile, Raffan says, keeping Labs trim requires disciplined owners.
“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.”
The study was published in Cell Metabolism.
Viviane Richter is a freelance science writer based in Melbourne.
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