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There’s a Gene That Controls Appetite in Dogs and Embark Now Tests For It

December 10, 2019

Labrador Retrievers are America’s most popular dog breed, and for good reason—they’re known for being loyal, friendly, and great with kids. Another thing they’re famous for: their appetite. If you’ve ever had a Lab, you may know what we’re talking about—the pups will often devour just about anything in sight, edible or not. 
 
But a 2016 study from scientists at the University of Cambridge, UK showed that Labs aren’t to blame for their perceived gluttony; it’s in their genes. The researchers studied 310 Labradors that were either companion dogs or assistance animals, examining three genes thought to influence canine obesity based on studies in other species. They also assessed the dogs’ eating behavior and body fat levels

With two of the genes, the researchers didn’t find a link to eating behavior or obesity, but the other one, known as POMC (short for pro-opiomelanocortin), was just what they had been looking for. They discovered that dogs missing a small portion of the POMC gene sequence were likely to weigh more and have more body fat and higher levels of food motivation. (More on that below.) 

As of today, Embark’s testing includes the POMC mutation, which is common in both Labrador Retrievers and Flat Coated Retrievers. Dogs already in our database will also receive this result, which you can find under traits in their profile. This is possible because it’s a linkage test, meaning we’ve taken advantage of the fact that DNA sequences that are close together on a chromosome tend to be inherited together. We can use genetic variation surrounding a mutation (i.e. “linked” to it) to infer the presence or absence of a mutation of interest. Linkage tests do not directly examine a mutation of interest; therefore, they may not always be perfectly predictive of your dog’s true genotype. By our most recent analysis, Embark linkage test is over 98% predictive of POMC genotype. 

Why POMC is Related to Obesity in Dogs

The POMC gene codes for two proteins that help the brain regulate appetite, essentially letting your dog know that it’s time to stop eating. It’s believed that with lower levels of these proteins, the “I’m full” message is never received and the pups continue to feel hungry, even if they’ve just feasted. 

In the University of Cambridge study, almost 25% of the Labs had the POMC mutation, which is known as a deletion since the gene is partially or fully missing. However, when it came to the assistance dogs, the number skyrocketed to more than 75%. It’s likely that over time, these dogs have inadvertently been bred to have this mutation; with their high levels of food motivation, they’re easy to train, which essentially makes them better at their job. 

POMC Also Affects Humans

POMC doesn’t just affect canines, though. POMC neurons (brain cells that express POMC) play a role in regulating hunger in other species, too, including humans. Research has found that exercise and circadian rhythms impact POMC levels, which in turn has a result on hunger and satiation. 

Scientists at the University of Texas Southwestern Medical Center ran an experiment on mice to better understand the effects of exercise on the melanocortin circuit, which consists of two types of neurons, including POMC. They placed healthy adult male mice on moving mini treadmills for three 20-minute intervals, and compared them to mice that didn’t exercise. The researchers found that post-workout, the mice’s POMC neurons were much more active, explaining why they ate less than they had before the researchers exposed them to the running regimen. Though the study was done on mice rather than humans, it can help us understand the important role POMC plays in regulating appetite and weight across many species.  

What to Do If Your Dog Has the POMC Mutation

Back to our canine companions: Knowing that your dog has the POMC mutation will at the very least help explain their obsession with food. But this result can give you more than a better understanding of your pup’s quirks. You and your vet can use the information to get proactive about diet and exercise to help prevent them from becoming obese, which increases the risk for orthopedic disease, Type II Diabetes, cardiovascular disease, and cancer. Still, keep in mind that the POMC mutation is not a guarantee of obesity, nor does it directly cause disease (which is why we list it as a trait rather than health condition). 

If you know your dog is a chow-hound, our vets recommend a couple steps you can take:

 1. Try smaller, more frequent meals
: Feed your dog less, but more often. This can raise their baseline feeling of satiety.

2. Track your dog’s body condition: You may be able to weigh your dog regularly using a pet scale. Alternatively, snap photos of each month, capturing them from the side (in profile), and from overhead. Comparing the photos over time, you can see whether your dog’s shape has changed. Our vets suggest using this body condition score scale to better understand your dog’s ideal weight.

Body Condition Scale for Dogs
wsava.org

 

Another pro tip? Take advantage of your dog’s love of food by using treats to train them. Food-motivated dogs can be great fits for obedience, rally, or agility.  

There’s still more to discover about POMC, especially in mixed breed dogs. You can help us advance our research on this trait by telling us about your dog in this quick survey.