Obesity, Appetite, and a Gene Mutation in Labrador Retrievers


Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

Weight Gain in Labrador Retrievers

Labrador Retrievers are usually affectionate dogs that make wonderful pets. Unfortunately, some have a tendency to gain weight. In fact, pet experts often mention the breed as the one that is most likely to become obese. In some dogs, the weight gain is probably caused by a high calorie intake and insufficient exercise. There may be another factor at work, however. Researchers have discovered that a significant percentage of Labs have a gene mutation linked to increased weight. The mutation may prevent their hunger from being satisfied and increase their obsession with food.

Misha is my Labrador Retriever. Like most Labs, he loves to eat. We mustn't assume that a dog who eats a lot has a genetic problem that increases their hunger. Even if a dog has the mutation, the steps for keeping him or her at a healthy weight are the same. The task may be harder in an animal with the mutated gene, though.

Dog Obesity Statistics

The research into the gene mutation in Labrador Retrievers was carried out by a group of twenty-two scientists. Most of them are associated with the University of Cambridge Metabolic Research Laboratories. Based on a survey of the scientific literature, the researchers have discovered the following facts.

  • In developed countries, between 34% and 59% of dogs are obese.
  • Recent increases in canine obesity and in diseases linked to the obesity mirror changes seem in humans.
  • Despite the above facts, obesity is more common in some dog breeds than others, suggesting that genetics plays a role in the disorder.

Of all dog breeds for which data have been reported, Labrador retrievers have the greatest documented obesity prevalence .... and have been shown to be more food motivated than other breeds.

— Cell Metabolism Journal Article

A Gene Mutation That May Affect Hunger and Appetite

The gene that is linked to a Labrador Retriever's weight gain and obesity is known as the POMC or pro-opiomelanocortin gene. (There may be other genes that can also cause Lab obesity.) The mutation consists of the deletion of a section of DNA from the gene. DNA, or deoxyribonucleic acid, is the chemical that makes up genes. Genes contain coded instructions for making proteins. If a section of DNA is missing, so is part of the instructions.

The POMC gene codes for a protein that splits up to form two neuropeptides: beta-MSH (melanocyte-stimulating hormone) and beta-endorphin. As a result of the mutation, the production of the neuropeptides is assumed to be disrupted. This assumption wasn't tested in the research, however. The chemicals are thought to play an important role in ending the sensation of hunger once a dog eats, although there are other chemicals and brain pathways involved in ending hunger.

When the dog experiences a weaker signal "telling" it that it's no longer hungry, its appetite may not be completely satisfied even after it has eaten what should be a sufficient amount of food. This may be the reason for the increased food searching behaviours and weight observed in many dogs with the mutation.

Prevalence of the Mutated Gene

The mutated gene was found in about a quarter of the 310 Labrador Retrievers involved in one trial carried out by the researchers. In another trial involving a total of 411 dogs from the United States and the UK, researchers found that 23% of the Labrador Retrievers had the mutated gene. The dogs included both companion and assistance animals. Interestingly, the gene was discovered in 76% of the 81 assistance dogs that were checked. The greatly increased percentage in assistance dogs was surprising to the researchers.

Genes give dogs and humans many of their characteristics. A gene exists in slightly different variations called alleles. The combination of alleles that an animal possesses for a certain characteristic is known as a genotype. The mutated POMC allele in dogs was apparently able to exert its effect whether it was present in a heterozygous genotype (one normal version of the gene and one mutated form) or in a homozygous genotype (two mutated forms of the gene). Dogs with both of these genotypes were often overweight or obese.

Effects of the Mutation

According to owner reports, dogs with the mutation are more motivated to find food than those without it and perform behaviour such as food scavenging and begging more often. In addition, most of the dogs in the experiment who had the mutation were significantly heavier than their counterparts without the mutated gene. Many were overweight or obese. This wasn't true for all of the dogs with the mutation, however. This may have been due to diligent food and portion control by the owners.

The researchers discovered that some dogs without the mutation were obese, which shows that there are additional factors—genetic or otherwise—that control body weight in Labs.

The mutated gene has been found in flat-coat retrievers and has been linked to obesity in that breed. Flat-coated retrievers are close relatives of Labs. Some mice, rats, and humans also have POMC genes associated with obesity. The mutated dog gene is most similar to the one in humans, which means that research in dogs may be helpful for us as well as our canine companions.

Assistance Dogs and a POMC Gene Mutation

The researchers have an interesting hypothesis for the greatly increased prevalence of the mutation in assistance dogs. They emphasize that their hypothesis is only a possibility and needs to be tested. Assistance dogs are generally given food rewards when they perform a desired behaviour, at least in the first stage of their training. Therefore all other things being equal, a dog that is more strongly motivated by food could be easier to train and make a better assistance dog. Adult dogs who possess the POMC mutation and pass it to their offspring might be seen as producers of the best puppies and favoured as parents. The mutation would therefore become more common in the assistance dog population.

The hypothesis sounds quite plausible, although I do wonder whether an assistance dog with the POMC mutation could become so distracted by the presence of nearby food that they no longer do their job properly. Ignoring temptation would have to be a major part of their training.

I got Misha from a lady who breeds her dogs to produce puppies for the Pacific Assistance Dogs Society (PADS). The plan was to train some of Misha's litter for PADS. Misha has an unusually strong interest in finding food compared to my other Labs. The combination of these factors makes me wonder if Misha has the POMC mutation. Identifying the presence of the gene would certainly make me feel sorry for him but wouldn't change the steps that I need to follow in order to keep him at a healthy weight.

How to Keep a Dog at a Healthy Weight

The following steps should enable a dog to maintain a healthy weight. They are especially important for a Labrador Retriever that may have a gene that contributes to weight gain and obesity. If your dog gains weight even after the steps are being followed, it's a good idea to see a vet. The dog may have a medical problem that causes weight gain, such as hypothyroidism.

  • Feed your dog an adequate amount of food at meal times and make sure that the food is healthy and nutritious.
  • Check with a vet or your breeder if you have any doubts that your dog is being given enough (or too much) food. Labels on dog food packages may be a useful guide but may not be completely reliable.
  • Check your dog's weight frequently. Ask your vet whether the dog is at a suitable weight and check whether any adjustments to diet or exercise are needed.
  • Consider the use of treats very carefully. Multiple people in a family giving high calories treats to a pet at different times of the day can cause weight gain. If you want to give treats, examine their nutrition and calorie content and decide when and how often the dog will be given the treat.
  • Don't give your dog food from your meal while you're eating. Even as a puppy, a dog should be trained not to beg at the table. If human food is given to a dog, it should be part of their regular meal. (Be very careful if you do this. Some human foods are dangerous for dogs.)
  • Some dogs can be very cute and persuasive when they beg for food. They quickly discover behaviour that their owner finds hard to resist. Harden your heart and don't succumb if your dog begs. That being said, if a dog repeatedly asks for food even when you don't capitulate, you should consider why they are behaving in this way.
  • Give your dog regular and sufficient exercise. The type of exercise is also important to consider. Some dogs require a more vigorous workout than others.

Food Stealing and Scavenging in Dogs

Food stealing and scavenging can not only cause a dog to gain weight but can also be dangerous if the dog eats certain foods. It can also be bad for oral health. Misha is a lovely dog and is generally well behaved, but he has stolen food in the past. I make sure that I keep most food out of his reach now. Training and discipline have definitely improved his behaviour, and he does leave food alone when I tell him to. Food is still a big temptation for him, though. It's not his only interest in life, but it's a major one.

Of course, training and discipline mustn't hurt a dog either physically or psychologically. Every prospective dog owner should do some research to discover safe and effective ways to train and discipline a puppy or a dog before they bring him or her into their home.

There are at least two important reasons for hiding certain foods from all dogs. One is that some foods commonly eaten by humans are unsafe for dogs and should never be eaten by them. Another is that eating a large amount of food very quickly has been associated with bloat, a potential deadly condition in dogs. Raiding a large bag of dry dog food is especially dangerous in this regard.

Tips for Preventing a Dog From Stealing Food

There are two ways to prevent a dog from stealing food: train them to leave food alone or hide it from them. I use a combination of both methods. Training is especially important when a dog scavenges outside the home where food can't be hidden. It's possible that they may pick up something dangerous while doing this.

Here are some tips for hiding or removing food so that a dog can't get to it. I follow many of them myself.

  • Make sure that all food is put out of a dog's reach as soon as it's brought into the home. An enclosed area such as a high cupboard or a refrigerator is best.
  • Don't leave food on a table, countertop, or other exposed surface in your home.
  • If you're in the middle of making a meal in the kitchen and need to leave the room with food exposed, the kitchen door should be closed. If this isn't possible and your dog likes to counter-surf, the dog should be supervised by someone else or placed in a secure and comfortable area such as their crate.
  • If you have to leave a meal before finishing it and your dog isn't trustworthy when food is temporarily unattended, ask someone else to watch the meal, take the meal with you, or place it in an inaccessible place.
  • Store unused pet food in a secure area.
  • If your dog steals another pet's food as soon as your back is turned, supervise the other pet as it's eating or feed it in an area that is inaccessible to your dog.
  • Remove food left or dropped by other pets to prevent your dog from scavenging.
  • Place food scraps, empty food containers, and garbage in a secure container or a place that your dog can't reach.
  • Don't leave your dog alone in a car with either human or pet food.

Learning More About the POMC gene

Hopefully researchers will eventually learn more about the mutated POMC gene and the way in which it affects both dogs and humans. I would also be interested in research that compares the frequency of the mutation in show line and field line Labrador Retrievers. Show line dogs are generally stockier animals than field line ones.

It would be wonderful if researchers found a way to safely compensate for the effect of the mutated gene by biological or chemical means. Until then, dog lovers should try to keep their Labrador Retrievers at a healthy weight to reduce the chance of disease and to help them enjoy life more.

References

  • Why Labrador Retrievers are more interested in food than other breeds: a news release for the general public from the Cell Metabolism Journal
  • A Deletion in the Canine POMC Gene: the research report from the Cell Metabolism Journal
  • Weight problem in Labradors from New Scientist
  • Obesity in dogs from PetMD

© 2016 Linda Crampton

Linda Crampton (author) from British Columbia, Canada on June 03, 2020:

So do I, Siva. The Labrador retriever is a lovely breed.

Siva arun on June 03, 2020:

I love the Labrador dog very much

Linda Crampton (author) from British Columbia, Canada on March 19, 2018:

Having a dog who takes toast out of the toaster would be interesting! It can be a challenge to keep some dogs at a healthy weight. I'm glad yours got back into shape.

Melody Lassalle from California on March 19, 2018:

I had a Lab/Golden mix who was the worst thief. Perhaps she had this mutation. She was tall enough to take toast out of the toaster, food off a plate on the table. Once she stole a whole loaf of fresh made bread off the counter. Our Vet called Labs Trash Can Dogs bēcause they'd eat anything.

At 5 years old, she was 10 lbs overweight and had to go on a diet. Worst couple of months in my household! Eventually, switching her food, giving her more nutritious treats, and skipping the people food got her back into shape.

Linda Crampton (author) from British Columbia, Canada on October 18, 2017:

Thanks for sharing the story of your cat and for rescuing him, Nancy. One of my cats is big, too, but the vet says that he isn't overweight. He's just a big boy!

Nancy Owens from USA on October 18, 2017:

I think my cat has this disease, Lol! He was an orphan baby whose mother was taken by a wave of distemper in Montana. There was a very long line of feral cats living on a large wheat ranch where I lived. His eyes weren't open yet, so I bottle fed and then started him on baked chicken drippings for his first solid food. Now he weighs in at about 25 pounds. He is very large and I joke that he is a Viking kitty. Mostly he is bone and muscle, but every winter he gets too fat. Right now he probably needs to lose a full pound. Not sure about his current weight. He will go in for his checkup soon, so we will find out.

Linda Crampton (author) from British Columbia, Canada on October 29, 2016:

She sounds like an energetic dog! Labs do love their food, even when they're not obese. I hope your dog continues to stay in good shape.

Pau on October 29, 2016:

My 9 month old female lab has a very huge appetite, more than other breeds I have. Every morning I have to feed her 2x because she will keep on bugging me If I don't feed her. However shes not obese, she has many playmates. She gets a lot of exercise everyday.

Linda Crampton (author) from British Columbia, Canada on July 29, 2016:

Thanks for passing the article on to your neighbor, Dianna. I love Labrador retrievers. In my experience, they are very friendly animals, like the ones that live near you.

teaches12345 on July 28, 2016:

My neighbor has two labradors and they are so friendly. I will have to pass on this information to her so she can keep an eye on their eating habits.

Linda Crampton (author) from British Columbia, Canada on May 30, 2016:

Hi, Bill. Thanks for the comment about the article and my dogs. I think all dogs are beautiful! I hope the week ahead is a great one for you.

Bill De Giulio from Massachusetts on May 30, 2016:

Hi Linda. Your labs are beautiful. Great information as always. I was not aware of the POMC gene, very interesting. Have a wonderful,day.

Linda Crampton (author) from British Columbia, Canada on May 29, 2016:

Thank you very much for commenting, Larry. I hope your dog stays healthy and happy for a long time to come. I've never owned a Jack Russell, but I think it's an interesting breed.

Larry Rankin on May 29, 2016:

Very interesting stuff. I have a Jack Russell that is 11. It seems as the years go by keeping her slim is more difficult, but I wouldn't say she has a tendency towards obesity.

Great read!

Linda Crampton (author) from British Columbia, Canada on May 24, 2016:

Hi, Audrey. I love big dogs, too - as well as small and medium-sized ones! There may not be a gene mutation involved in all cases of Lab obesity, but a genetic problem may be responsible for more cases than we realize. It's an interesting thought.

Audrey Howitt from California on May 24, 2016:

I love bigger dogs, labs included and it can be hard not to overfeed them--such an interesting article--I didn't realize there was a gene mutation involved

Linda Crampton (author) from British Columbia, Canada on May 23, 2016:

Hi, Deb. Yes, there could be more than one reason for weight gain in Labs. I hope researchers explore the possible reasons thoroughly. We need to fight obesity in both dogs and humans.

Deb Hirt on May 23, 2016:

I found this of great interest, as I have known many people with overweight labs, ad these were dogs that were very active under normal circumstances. This gene could be much more prevalent, or human food could be a bigger culprit.

Linda Crampton (author) from British Columbia, Canada on May 13, 2016:

Thanks for the visit, Martie. I hope that in the future there will be a way to solve genetic problems in both dogs and humans. It would be wonderful to eliminate health disorders caused by gene mutations.

Martie Coetser from South Africa on May 13, 2016:

Very interesting, thank you, Alicia and all researchers. Why Labradors have a tendency to gain weight, was indeed a question on my mind. I wonder when will it be possible to replace bad genes with good ones?

Linda Crampton (author) from British Columbia, Canada on May 12, 2016:

Thank you for sharing the information, DDE. The facts that you've mentioned are important for dog owners to remember.

Devika Primić from Dubrovnik, Croatia on May 12, 2016:

I recently watched a documentary on why pet owners have overweight pets. Over feeding, and less exercise was the problem. The other issue is when pet owners have more than one dog and keep their feeding dishes in different spaces one of the dogs usually eats what the other dog has left and that allowed for that dog to grow over weight. You shared useful points.

Linda Crampton (author) from British Columbia, Canada on May 09, 2016:

Hi, Suhail. Thanks for sharing the information with your relatives. Labrador Retrievers make lovely pets, but it is important to be careful with their food intake.

Suhail and my dog on May 09, 2016:

Although I don't have a labrador, but my brother and his family may end up having one. I will definitely refer this article to his daughters.

Linda Crampton (author) from British Columbia, Canada on May 08, 2016:

Thank you very much for commenting and for sharing the information with your friend, Kali. It's a great shame that some Labs are obese. They are wonderful dogs.

Kaili Bisson from Canada on May 08, 2016:

What a fascinating article. I had never heard of this before, but it seems it is fairly prevalent in this breed. I am going to pass this to a friend who has one of these doggies. Thank you!

Linda Crampton (author) from British Columbia, Canada on May 08, 2016:

I loved reading about your Labs, Faith! It sounds like you treat Max like I treat Misha. Unfortunately, like your black Lab, Bess had hip dysplasia. She has passed on but is still very much in my mind.

Thank you so much for the shares, Faith. I appreciate them all.

Faith Reaper from southern USA on May 08, 2016:

This is such an important hub, Linda.

We love our chocolate lab, Max, so much. He is very healthy as we only feed him the best dog food we can find and no food from the table ever. He does get a doggie treat now and then. He is one of the tallest labs we've ever had with such a shiny coat.

We did have a couple of black labs and one yellow lab when my children were growing up. One of the black labs did have hip dysplasia, which is so sad for any dog. He was one dog who would try to snatch food from our hands whenever we were outside having a BBQ.

Misha, Owen and Bess are such beautiful dogs! Bess reminds me of my childhood yellow Lab, Brownie, he was a three-legged dog who adopted our family and lived with us throughout our childhood!

I am sharing this important information everywhere.

Linda Crampton (author) from British Columbia, Canada on May 08, 2016:

Hi, Vellur. Thanks for the visit. I'm happy to say that Misha is in good health at the moment.

Nithya Venkat from Dubai on May 08, 2016:

An interesting and informative hub about weight gain and appetite in Labrador Retrievers. A gene mutation can wreak havoc, hope Misha is in the best of health now.

Linda Crampton (author) from British Columbia, Canada on May 08, 2016:

Thank you very much, Bill. I appreciate your comment a great deal.

Bill Holland from Olympia, WA on May 08, 2016:

One of the things I enjoy about your articles is the fact that they are so original....and informative...and just well-written. This one is no exception.

Linda Crampton (author) from British Columbia, Canada on May 07, 2016:

Hi, Flourish. Genetics is certainly an interesting topic. One of my cats is very large while the other two - one of which is the same breed as the big one and has one parent in common - are small. More than one vet has said that the big one isn't overweight. He's just a giant!

FlourishAnyway from USA on May 07, 2016:

There definitely seems to be some selection in assistance dogs for factors that are conflated with this gene. You have such interesting topics and beautiful dogs. With my cats, they all have equal access to food and are well exercised but several are obese and others are normal or skinny minnies. It does make you wonder about genetics.

Linda Crampton (author) from British Columbia, Canada on May 07, 2016:

I'm happy to read about your view of Labs, Mel! Your description of a Labrador Retriever's needs is absolutely right. They are lovely dogs, but they do need a lot of attention.

Mel Carriere from Snowbound and down in Northern Colorado on May 07, 2016:

I love labs. They are some of the most mailmen-friendly dogs around. I think Labs need a lot of exercise. They are retrievers and have a natural instinct to run, track and fetch things. People that have animals like this really have to keep them engaged, in order to keep them healthy. Great hub!

Linda Crampton (author) from British Columbia, Canada on May 07, 2016:

Thank you for the comment and for sharing the interesting information, DrMark. The situation that you've described certainly does sound like a hard cycle to break!

Dr Mark from The Atlantic Rain Forest, Brazil on May 07, 2016:

Very interesting article! Since one of the first selection tests for an assistance dog is "retrieval", it sounds like we are selecting for the obesity gene since the puppies that retrieve may in fact be running after an object looking for food. When the object is not something that they can eat, they bring it back to the human and hope for a treat (since all puppies learn early that humans are a source of food). It sounds like a hard cycle to break!

Linda Crampton (author) from British Columbia, Canada on May 07, 2016:

Thanks for the comment, Jackie. I agree - dogs and children love food as a reward, but it's very important to be careful with their health.

Jackie Lynnley from the beautiful south on May 07, 2016:

You give some great advice. It is very hard to not spoil our dogs and over feed them but for their health we never should although I think most of us use food for as a reward even for our kids much less our dogs!


Why Are Labradors So Greedy Compared to Other Dogs?

Why are labradors so greedy? A new study claims to finally have the answer! The study, supported by the Wellcome Trust, Medical Research Council Metabolic Diseases Unit, found genetic links between labrador retrievers and their motivation for food. These findings are one of the first to directly link a gene to canine obesity.

There is no doubt that labradors tend to be more obese than other breeds. Multiple studies have confirmed this is true, regardless of the dog’s owner 1 . Labradors are also more food-motivated than other breeds, as revealed by a questionnaire completed by 213 dog owners 2 . As to why labradors are so greedy has been a difficult question to answer, until now.

Investigating a Genetic Cause of Greediness

Eleanor Raffan, a veterinary surgeon and geneticist at the University of Cambridge began her investigation by selecting three obesity-related genes. Each of the selected genes were known to affect weight in humans.

Analysis found a mutation in a gene known as POMC which was predicted to interfere with the body’s appetite. The same POMC gene is already associated with differences in body weight in humans.

There are a number of ways a gene can become mutated. In this case, a section of the gene has been deleted. This is known as a deletion mutation. This deleted section is also missing in a number of human obesity cases.

The mutation was expected to hinder a dog’s ability to produce the neuropeptides β-MSH and β-Endorphin, which are usually involved in switching off hunger after a meal.

“There are even some rare obese people who lack a very similar part of the POMC gene to that which is missing in the dogs”
Stephen O’Rahilly – Co-director, Wellcome Trust-Medical Research Council

POMC Gene Affects Behaviour and Weight Gain

After the initial findings, the researchers studied a larger sample of 310 labrador retrievers. In this investigation a number of food-related behaviours were found to be linked to the POMC mutation.

Owner’s recorded more ‘food-motivated’ behaviours in labradors with the POMC mutation. These dogs were especially attentive at meal times, begging for food and searching for scraps more frequently. On average, POMC deletion was found to be associated with a 1.9kg increase in body weight 3 .

If you’re trying to keep a labrador slim, unfortunately the odds are stacked against you. Evidence suggests dogs can influence the quantity of food offered to them by their owners 4 and labradors are particularly good at it.

The POMC mutation makes labradors more likely to increase food intake by scavenging or begging. In turn, this is going to cause weight gain.

Although the deletion mutation of the POMC gene is linked with an increased weight, not all dogs were overweight. In fact, owners of dogs that are highly food-motivated are more likely to limit their pet’s food portions.

Waiting by the dinner table for some lunchtime scraps? Image: Daphné

Guide Dogs More Likely to Have POMC Mutation

The POMC mutation linked to increased weight was detected in 23% of the dogs included in the study. Of the 81 assistance labradors included in this cohort, 76% carried the mutation.

Eleanor Raffan, a veterinary surgeon and geneticist at the University of Cambridge suggests the selection of the dogs could be responsible. Assistance dog training typically involves lots of food rewards. Increased ‘greediness’ associated with POMC favours dogs with the mutation when selecting guide dogs.

How Greedy is Your Labrador?

Labradors are by far the most common dog in the UK and US, so many of you can relate to their obsession with food! How much does your labrador eat? What is the weirdest thing they have eaten? Let us know in the comments below.

If you’re a Labrador owner wondering if your lab is overweight, try body condition scoring. If you want to get your pooch back to a healthy weight, you could also try our new calorie monitoring tool, HealthTrak. HealthTrak helps you log weights, meals and overall progress as well as earning some achievements along the way!


Why are so many Labradors fat?

Like owner, like dog? Almost two-thirds of dogs in developed countries are overweight, with Labradors having the highest rate of canine obesity. Now we know the secret to their insatiable appetite: mutations in a gene that has been linked to hunger in humans.

Conor O’Donovan at the University of Cambridge and his colleagues found the genetic variant by studying 310 Labrador retrievers, assessing both their weight and their desire for food.

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They found that 23 per cent of the dogs carried at least one copy of a mutant form of a gene called POMC, which encodes proteins that help switch off hunger after a meal. For each copy of the mutant gene, a dog was on average 1.9 kilograms heavier than Labradors with no copies of the variant.

Problems with POMC also affect humans. Babies with compromised POMC function are constantly hungry, and become obese at a very early age.

But research into this gene’s role in obesity has been hindered by the fact that the version of it that rats and mice have is very different from ours. The latest study shows that POMC in Labradors is more similar to ours, meaning these dogs may help us to better understand the importance of this gene in human weight gain.


Why Labrador retrievers are more interested in food than other breeds

Dog owners tell their vets that Labrador retrievers are always interested in food, and new work shows there might be a biological truth to the claim. A May 3 study in Cell Metabolism links a gene alteration specifically found in Labs and related flat coat retrievers to greater food-motivated behavior, describing the first gene associated with canine obesity. The variation also occurs more frequently in Labradors chosen as assistance dogs, and might explain why these canines seem more trainable with food rewards.

Labrador retrievers are more interested in food and tend to be more obese than other breeds, regardless of owner. "Whenever there's something more common in one breed than another, we think genetics are involved," says Eleanor Raffan, a veterinary surgeon and geneticist at the University of Cambridge who previously studied human obesity before investigating the canine angle.

Starting with an initial cohort of 15 obese and 18 lean Labrador retrievers, Raffan and her colleagues selected three obesity-related genes to examine, all of which were known to affect weight in humans. This first analysis turned up a variation in a gene called POMC. In more of the obese dogs, a section of DNA was scrambled at the end of the gene. The deletion is predicted to hinder a dog's ability to produce the neuropeptides β-MSH and β-Endorphin, which are usually involved in switching off hunger after a meal.

In humans, common variants in POMC have been associated with differences in body weight. "There are even some rare obese people who lack a very similar part of the POMC gene to that which is missing in the dogs," says Stephen O'Rahilly, co-director of the Wellcome Trust-Medical Research Council Institute of Metabolic Science and a senior author on the study.

In a larger sample of 310 Labrador retrievers, Raffan and her colleagues discovered a host of canine behaviors associated with the POMC deletion. Not all Labs with the DNA variation were obese (and some were obese without having the mutation), but in general the deletion was associated with greater weight and, according to an owner survey, affected dogs were more food-motivated--they begged their owners for food more frequently, paid more attention at mealtimes, and scavenged for scraps more often. On average, the POMC deletion was associated with a 2 kg weight increase.

"We've found something in about a quarter of pet Labradors that fits with a hardwired biological reason for the food-obsessed behavior reported by owners," says Raffan. "There are plenty of food-motivated dogs in the cohort who don't have the mutation, but there's still quite a striking effect."

The researchers found that the POMC deletion occurs in roughly 23 percent of Labrador retrievers overall, based on further sampling of 411 dogs from the UK and US. Of 38 other breeds, the deletion only showed up again in flat coat retrievers, related to Labrador retrievers, and weight and behavior were similarly affected.

Notably, the POMC deletion was markedly more common in the 81 assistance Labrador retrievers included in the study, occurring in 76 percent of these dogs. "We had no initial reason to believe that the assistance dogs would be a different cohort," says Raffan. "It was surprising. It's possible that these dogs are more food-motivated and therefore more likely to be selected for assistance-dog breeding programs, which historically train using food rewards."

But, Raffan cautions, the results could also be just a quirk of the data. "We haven't yet looked at puppies and asked if they're more likely to qualify as an assistance dog if they have the mutation," she says.

The study adds to a growing body of knowledge about the biological reasons driving weight. "The behavior of dogs carrying this mutation is different," says Raffan. "You can keep a dog with this mutation slim, but 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, because it's much harder for you than it is for someone with a less food-motivated dog."

Moving forward, Raffan and her colleagues are also investigating the potential therapeutic implications for humans with obesity. The impacts of mutation in POMC have previously been difficult to research because in mice and rats, animals typically used to study obesity, the gene is quite different from the human version. "Further research in these obese Labradors may not only help the well-being of companion animals, but also carry important lessons for human health," says O'Rahilly.


My Dog Eats Anything and Everything!

Domestic dogs, including the Labrador, are classed as omnivores. So, they can eat and get nutrients from a large variety of foods, including meat and plant based foods.

Dogs are also often opportunistic eaters, meaning they’ll eat what they can, whenever they can!

Labs are known to eat lots and quickly. But, this doesn’t just mean their own food.

Many Labradors will eat anything they’re given. And, some might even eat things they shouldn’t, like sneaking food from your counters and the trash.

They may also eat things they shouldn’t, like household items, toys, socks, stones, poop, and dead things they find on walks.

So, eating everything can become a problem. And to find a solution, we need to understand the cause of the problem.


Watch the video: Scientists figured out why so many Labrador Retrievers are fat


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