The Labrador retriever, known as one of the greediest breeds of dog, is hard-wired to overeat, research suggests.
The dog is more likely to become obese than other breeds partly because of its genes, scientists at Cambridge University say, according to BBC.
The gene affected is thought to be important in controlling how the brain recognises hunger and the feeling of being full after eating.
The research could help in the understanding of human obesity.
“About a quarter of pet Labradors carry this gene [difference],” lead researcher Dr Eleanor Raffan told the BBC.
“Although obesity is the consequence of eating more than you need and more than you burn off in exercise, actually there’s some real hard-wired biology behind our drive to eat,” she added.
Canine obesity mirrors the human obesity epidemic, with lifestyle factors such as lack of exercise and high-calorie food both implicated – as well as genetics.
As many as two in three dogs (34-59%) in rich countries are now overweight.
The Labrador has the highest levels of obesity and has been shown to be more obsessed with food than other breeds.
Researchers screened more than 300 Labradors kept as pets or assistance dogs for known obesity genes in the study, published in the journal Cell Metabolism.
The international team found that a change in a gene known as POMC was strongly linked with weight, obesity and appetite in Labradors and Flat-Coated retrievers.
In both breeds, for each copy of the gene carried, the dog was on average 2kg heavier.
Other breeds of dog – from the Shih Tzu to the Great Dane – were also screened, but the genetic difference was not found.
However, the variation was more common in Labradors working as assistance dogs, which the researchers say might be because these dogs are easier to train by rewarding with food.
H.Z