Always-hungry Labradors: the POMC gene and measured meals

Around one Labrador Retriever in four carries a deletion in a gene called POMC, and for each copy a dog carries it weighs on average 1.9 kg more. That finding, from a University of Cambridge study published in 2016, gave a biological explanation for something Labrador owners have long described: a dog that begs, scavenges and steals food even when it has just eaten. The begging is not simply bad manners. For many Labradors the drive to eat is set higher than in most other dogs, and the owner's feeding routine is the main thing standing between that drive and obesity.

What the POMC deletion is

The Cambridge team looked at 310 pet and assistance-dog Labradors. Veterinary professionals weighed each dog and scored its body condition, owners filled in a questionnaire on food-related behavior, and the researchers sequenced candidate obesity genes. They found a 14-base-pair deletion in the pro-opiomelanocortin (POMC) gene. In the published paper in Cell Metabolism, the deletion was linked to higher body weight, more body fat and higher food-motivation scores, with each copy of the gene adding to the effect.

Among the other breeds tested, the deletion turned up only in the closely related Flat-Coated Retriever, where it had the same association with weight and appetite. It was even more common in Flat-Coats than in Labradors, although Flat-Coats had not been thought of as an obesity-prone breed. A later study of 272 dogs from four obesity-prone breeds (Labradors, Golden Retrievers, Beagles and Cocker Spaniels) again found the deletion only in the Labradors, and confirmed its link with body weight.

Eleanor Raffan, the study's first author, put it simply: people who live with Labradors often say the dogs are obsessed by food, and that fits what is known about this genetic change.

What the mutation changes

The POMC gene makes a precursor protein that the body cuts into several smaller signaling molecules. Two of them are lost when the deletion is present. Beta-melanocyte-stimulating hormone (beta-MSH) acts on melanocortin receptors in the hypothalamus, part of the system that reduces appetite and keeps energy expenditure up. Beta-endorphin is one of the body's own opioids and is involved in reward. Dogs with the deletion still make alpha-MSH, a related signal, so the pathway is weakened rather than switched off.

Follow-up work from the same group, published in 2024, measured what this does to a living dog. Labradors carrying the deletion had a markedly lower resting energy expenditure and reacted more strongly to a food cue, a sign of greater hunger or wanting. When they were offered a large meal, though, they did not eat more before stopping than dogs without the deletion, and their enjoyment of food looked the same.

That detail matters. The common description of these dogs as "never feeling full" overstates it. A better summary is that affected Labradors are hungrier between meals and burn fewer calories at rest. Both push weight up. A carrier fed the same portion as a non-carrier of the same size can gain weight on it, and it will work harder to find extra food. Management comes down to how much food goes in and how it is delivered.

Why the variant is common in working Labradors

The deletion was significantly more common in Labradors that had been selected to become assistance dogs than in pet Labradors. Food rewards are central to training, and a dog that will work hard for a small piece of food is easier to train. The researchers suggested that carrying the variant may make a dog more willing to work for a reward, which would make it a double-edged trait: helpful for training, harmful for weight.

Selection for trainability is a plausible reason the variant has stayed common in the breed, though the studies did not test that history directly. Labradors without the deletion are also typically keen on food. The mutation adds to a breed tendency that already exists.

Slowing meals down

The gene cannot be changed, but the way a fixed ration is eaten can. A carrier burns less energy at rest, so the ration it needs may be smaller than the owner expects. Making that ration last longer, and giving the dog work to do for it, eases the gap between appetite and allowance. There is little research on whether food puzzles alone reduce weight in dogs, so these tools support a measured ration rather than replacing it.

• Slow feeder bowls have ridges or mazes that break the food into small pockets, so a meal that would be swallowed in seconds takes several minutes.
• Puzzle feeders and treat-dispensing toys release kibble only when the dog pushes, rolls or paws them.
• Scatter feeding means spreading part of a meal over a clean patch of lawn or a mat so the dog has to search for each piece by scent.
• Frozen stuffed toys hold a mix of soaked kibble or wet food. Any peanut butter used should be free of xylitol, which is toxic to dogs.
• Snuffle mats hide kibble in fabric folds and suit dogs that rush through puzzle toys.

Everything that goes into these toys comes out of the day's measured food, not on top of it.

Measured meals instead of free feeding

Free feeding does not suit this breed. Leaving food out all day relies on a dog regulating its own intake, and this breed is poor at it even without the deletion. Two measured meals at regular times make portions easy to control and give the dog a predictable routine.

Weigh the food on a kitchen scale. Cups are too rough. In a series of trials on dry kibble, people using measuring cups served portions that ranged from 18% too little to 80% too much, and the errors were worst with small portions. On a dog already prone to gaining weight, a daily overshoot of that size adds up within weeks.

The starting amount should be based on the dog's ideal weight, not its current one. If a Labrador weighs 38 kg (84 lb) and its vet estimates an ideal of 30 kg (66 lb), the pack guidance for a 30 kg dog is the place to begin, adjusted over the following weeks according to weigh-ins. Low-calorie vegetables such as plain green beans, raw carrot or a spoonful of plain canned pumpkin add bulk to a bowl without adding much energy.

Treats count. So do chews and table scraps. A common rule of thumb is to keep them to about 10% of daily calories. For training, many owners set aside part of the day's kibble in a pouch, so a dog that works for food all day is still eating its normal ration.

Keeping a hungry Labrador lean

Body condition scoring on the 9-point scale is more useful than the number on the scales alone. A dog at an ideal score of 4 or 5 has ribs that can be felt easily under a thin layer of fat, a visible waist from above, and a tuck behind the ribs from the side. Weighing monthly, on a clinic scale or a large home scale, catches the slow gain that is hard to see day to day.

The strongest evidence for keeping Labradors lean comes from a lifetime study of 48 Labradors paired by litter, sex and weight. One dog in each pair was fed 25% less than its partner, on the same diet, from eight weeks of age. The leaner dogs had a median lifespan 1.8 years longer, and chronic diseases such as osteoarthritis appeared later. Same breed, same food. Only the amount differed.

Exercise helps. It cannot make up for an oversized ration. Swimming and retrieving suit the breed and are easy on the joints. A Labrador that needs to lose weight should do so under a vet's plan, with a target weight, a calorie allowance and regular rechecks, because very fast loss can cost muscle as well as fat. For signs that a dog has already drifted above its ideal weight, see how to tell if a pet is overweight.

Sources

1. A deletion in the canine POMC gene is associated with weight and appetite in obesity-prone Labrador Retriever dogs. Cell Metabolism, 2016.
2. Genetic variant may help explain why Labradors are prone to obesity. University of Cambridge, 2016.
3. Confirmation that a deletion in the POMC gene is associated with body weight of Labrador Retriever dogs. Research in Veterinary Science, 2017.
4. Low resting metabolic rate and increased hunger due to beta-MSH and beta-endorphin deletion in a canine model. Science Advances, 2024.
5. Imprecision when using measuring cups to weigh out extruded dry kibbled food. Journal of Animal Physiology and Animal Nutrition, 2011.
6. Diet restriction and ageing in the dog: major observations over two decades. British Journal of Nutrition, 2008.