Are Labradors hungry all the time
Tubby Labradors May Be at the Mercy of Their Genes, Not Just Too Many Treats
Tubby Labradors May Be at the Mercy of Their Genes, Not Just Too Many Treats
One in four Labrador retrievers carries a gene that tricks their brain into thinking theyre starving
By Meghan Bartels
If your Labrador retriever seems hungry all the time, it may be because they are.
These dogs are notorious among veterinarians for their tendency to pack on the pounds. And in previous research, scientists found that one quarter of Labradorsas well as two thirds of a less common breed of dogs called flat-coated retrieverscarry a genetic mutation that is associated with obesity in other animals. And in new experiments, researchers found that dogs with this mutation both feel hungrier between meals and burn less energy than their counterparts do.
What we see in the dogs is that theyre getting this molecular starvation signal, says Eleanor Raffan, a veterinarian and geneticist at the University of Cambridge and a co-author of the new paper, which was published on March 6 in Science Advances. As a result, they try to eat more and dial down their energy expenditure.
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In the new study, Raffan and her colleagues wanted to understand how the mutation, which affects a gene called pro-opiomelanocortin (POMC), impacts the lives of dogs who carry it. So they recruited dozens of U.K.-based dog owners who were willing to take part in a series of experiments .
The first experiment, nicknamed the sausage in a box test, brought Labs into the lab about three hours after the dogs had eaten breakfast. Researchers showed each dog a sausage, then closed it in a plastic box with holes so the dog could smell but not eat the treat. Then they watched how the dogs interacted with the box and for how long. The researchers found that dogs with the POMC mutation were more focused on the sausage box, spending about twice as much time interacting with or manipulating it.
The researchers also had dog owners conduct an experiment at home. In this exercise, breakfast became an all-Fido-can-eat buffet in which dogs got a new can of food every 20 minutes until they stopped eating, vomited or reached the experiments maximum limit of 6.5 pounds of food. On average, all the dogs, whether they had normal POMC genes or not, ate about four pounds of foodan enormous amount, Raffan says. (Dogs with the POMC mutation ate somewhat more, though, and dogs without it were more likely to end the experiment by vomiting.) The result suggest that the mutation doesnt make a difference in how quickly dogs feel full. The increased focus on food by the POMC-mutation group, however, suggests these dogs would continue to seek out more food if it wasnt in front of them by, for example, begging or stealing.
The researchers also looked at the opposite side of the equation: how dogs burn energy. For this experiment, they recruited 19 flat-coated retrievers. (These dogs carry the POMC mutation more frequently than Labradors, and researchers wanted to compare dogs that didnt have the mutation at all with dogs that had it in both copies of the gene because they expected the results would be more subtle.) The dog owners coaxed their pets into falling asleep in a chamber that measured the metabolic gases they produced, which allowed the researchers to calculate how much energy they burned while at rest. The scientists determined that dogs with the POMC mutation used less energy than their counterparts.
Taken together, the experiments show the complex way in which the mutation affects a dogs brain and body, Raffan says: It makes them want food more without actually making them like a particular food more or need more food to feel full. Simultaneously, it makes them burn food more slowly. They get a kind of double whammy of both eating more and burning off fewer calories, meaning that theyre predisposed to obesity from both directions, Raffan says.
The mutation is the legacy of a now extinct breed called St. Johns water dogs, the ancestor of both Labradors and flat-coated retrievers. These dogs accompanied fishers and happily fetched fish out of the frigid waters of maritime Canada in the 16th and 17th centuries. You can imagine that, in that context, willingness to eat anything that came your way and have a little bit of a layer of blubber under your skin to keep you warm in the sea might have actually been quite a good idea and a bit of an advantage for those dogs, Raffan says.
But for modern pets, the mutation is more harmful because obesity can cause or exacerbate health issues ranging from breathing problems to skin disease to incontinence, Raffan says. In one survey, 11 percent of Labradors were obese, compared with 7 percent of non-Labradors. In another, 5 percent of Labradors were obese, and 36 percent were overweight.
Dogs with the mutation can stay at a healthy weight, but they need their owners help to do so. In particular, Raffan says that spreading out meals through the day, resisting the puppy eyes begging for human food and giving the dogs lots of exercise are key, as is giving them something to think about besides their innate hunger. We hate being hungry. You dont like it; I dont like it; the dogs probably dont like it either, she says. So keeping them distracted and occupied seems to be helpful.
Some Labradors Are 'Hungry All the Time' for a Good Reason, Scientists Warn
If your fluffy friend seems to be constantly ravenous, it might come down to their genes.
A quarter of all Labrador retriever dogs have a specific genetic mutation that causes them to feel hungry all the time but also burn fewer calories, according to a study published in the journal Science Advances.
This genetic mutation is in a gene called POMC, which plays a role in appetite and energy metabolism. Therefore, owners of dogs with a mutation in POMC may need to pay closer attention to their dogs' diets.
The paper reveals that 25 percent of Labradors and 66 percent of all flat-coated retriever dogs have the POMC mutation, meaning that they have an increased risk of obesity due to their higher appetite than other dogs. It also found that the dogs with the genetic mutation felt hungrier in between meals and used about a quarter fewer calories when at rest than dogs without the mutation. This means that they don't need to consume as many calories to just exist.
"We found that a mutation in the POMC gene seems to make dogs hungrier. Affected dogs tend to overeat because they get hungry between meals more quickly than dogs without the mutation," study author Eleanor Raffan, a neuroscience researcher at the University of Cambridge said in a statement.
"All owners of Labradors and flatcoated retrievers need to watch what they're feeding these highly food-motivated dogs, to keep them a healthy weight. But dogs with this genetic mutation face a double whammy: they not only want to eat more, but also need fewer calories because they're not burning them off as fast."
The paper describes how they tested 87 adult pet Labradors using a game called "Sausage in the Box," which involved placing a sausage in a box with a clear lid that had been perforated slightly, meaning that the dogs could smell the food but not eat it.
They found that despite all the dogs having been fed the same amount three hours prior, dogs with the POMC mutation tried significantly harder to get the sausage from the box than those without the mutation, indicating that they were feeling hunger more strongly.
Therefore, it might not necessarily be the dog's or the owner's fault if the dog gains weight despite eating what would usually be considered a healthy amount of food.
"People are often rude about the owners of fat dogs, blaming them for not properly managing their dogs' diet and exercise. But we've shown that Labradors with this genetic mutation are looking for food all the time, trying to increase their energy intake. It's very difficult to keep these dogs slim, but it can be done," Raffan said.
Interestingly, the POMC gene affected similar brain pathways in humans as it does in dogs. These findings in the Labradors are consistent with previous research into humans with mutations in POMC, who often become obese at a young age.
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Gene makes fat labradors permanently hungry
On walks in the countryside, Leo the labrador will break into farmers fields to eat their cabbages.
At home, he has to be locked out of the vegetable patch to stop him digging up and devouring carrots. And when he recently took part in a scientific study to see how much dog food he would consume before he felt full, the experiment had to be aborted for his safety when he refused to stop.
Despite all this, his owner, Kathryn Taylor, 63, who lives near Castle Douglas in Dumfries and Galloway, insists that Leo really is a very good boy. And now a study from Cambridge University has confirmed that he is not to blame for his seemingly insatiable appetite. Instead, he can point a
Genetic mutation in a quarter of all Labradors hard-wires them for obesity
New research finds around a quarter of Labrador retriever dogs face a double-whammy of feeling hungry all the time and burning fewer calories due to a genetic mutation.
This obesity-driving combination means that dog owners must be particularly strict with feeding and exercising their Labradors to keep them slim.
The mutation is in a gene called POMC, which plays a critical role in hunger and energy use.
Around 25% of Labradors and 66% of flatcoated retriever dogs have the POMC mutation, which researchers previously showed causes increased interest in food and risk of obesity.
The new study reveals how the mutation profoundly changes the way Labradors and flatcoated retrievers behave around food. It found that although they don't need to eat more to feel full, they are hungrier in between meals.
In addition, dogs with the POMC mutation were found to use around 25% less energy at rest than dogs without it, meaning they don't need to consume as many calories to maintain a healthy body weight.
"We found that a mutation in the POMC gene seems to make dogs hungrier. Affected dogs tend to overeat because they get hungry between meals more quickly than dogs without the mutation," said Dr Eleanor Raffan, a researcher in the University of Cambridge's Department of Physiology, Development and Neuroscience who led the study.
She added: "All owners of Labradors and flatcoated retrievers need to watch what they're feeding these highly food-motivated dogs, to keep them a healthy weight. But dogs with this genetic mutation face a double whammy: they not only want to eat more, but also need fewer calories because they're not burning them off as fast."
The POMC mutation was found to alter a pathway in the dogs' brains associated with body weight regulation. The mutation triggers a starvation signal that tells their body to increase food intake and conserve energy, despite this being unnecessary.
The results are published today in the journal Science Advances.
Raffan said: "People are often rude about the owners of fat dogs, blaming them for not properly managing their dogs' diet and exercise. But we've shown that Labradors with this genetic mutation are looking for food all the time, trying to increase their energy intake. It's very difficult to keep these dogs slim, but it can be done."
The researchers say owners can keep their retrievers distracted from this constant hunger by spreading out each daily food ration, for example by using puzzle feeders or scattering the food around the garden so it takes longer to eat.
In the study, 87 adult pet Labrador dogs -- all a healthy weight or moderately overweight -- took part in several tests including the 'sausage in a box' test.
First, the dogs were given a can of dogfood every 20 minutes until they chose not to eat any more. All ate huge amounts of food, but the dogs with the POMC mutation didn't eat more than those without it. This showed that they all feel full with a similar amount of food.
Next, on a different day, the dogs were fed a standard amount of breakfast. Exactly three hours later they were offered a sausage in a box and their behaviour was recorded. The box was made of clear plastic with a perforated lid, so the dogs could see and smell the sausage, but couldn't eat it.
The researchers found that dogs with the POMC mutation tried significantly harder to get the sausage from the box than dogs without it, indicating greater hunger.
The dogs were then allowed to sleep in a special chamber that measured the gases they breathed out. This revealed that dogs with the POMC mutation burn around 25% fewer calories than dogs without it.
The POMC gene and the brain pathway it affects are similar in dogs and humans. The new findings are consistent with reports of extreme hunger in humans with POMC mutations, who tend to become obese at an early age and develop a host of clinical problems as a result.
Drugs currently in development for human obesity, underactive sexual desire and certain skin conditions target this brain pathway, so understanding it fully is important.
A mutation in the POMC gene in dogs prevents production of two chemical messengers in the dog brain, beta-melanocyte stimulating hormone (-MSH) and beta-endorphin, but does not affect production of a third, alpha-melanocyte stimulating hormone (-MSH).
Further laboratory studies by the team suggest that -MSH and beta-endorphin are important in determining hunger and moderating energy use, and their role is independent of the presence of -MSH. This challenges the previous belief, based on research in rats, that early onset human obesity due to POMC mutations is caused only by a lack of -MSH. Rats don't produce beta-melanocyte stimulating hormone, but humans and dogs produce both - and -MSH.
