Neutering and “Hygge” Treats: Risk Factors for Obesity in Dogs

New research shows that overweight and obesity in dogs is a One Health issue, and neutering male dogs is a risk factor

Neutering and "hygge" treats: Risk factors for obesity in dogs. Photo shows hygge scene with woman and dog.
Photo: Monika Wisniewska/Shutterstock

By Zazie Todd, PhD

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When dogs are overweight or obese, it can affect their health and even shorten their lifespan significantly. So understanding the causes is important. New research from Denmark on the risk factors for dogs being heavy or obese raises questions about the role of the owner and the effects of spay/neuter surgery.

The study, published in Preventive Veterinary Medicine, finds that neutering increases the risk of being heavy or obese in male dogs, but not in female dogs because they are already at higher risk. The results also suggest we need to think of overweight and obesity in dogs as a One Health issue, because the health of people and their pets is interconnected.

Dr. Charlotte Reinhard Bjørnvad, first author of the study, told me in an email,
“The finding that neutering triples the risk of developing obesity specifically in male dogs is important. It seems to be much more common to neuter dogs in USA and the UK compared with Denmark, and it is important to factor this in for male dogs when deciding to castrate or not.”

The study looked at 268 dogs and their owners in Zealand (the eastern part of Denmark that includes Copenhagen, the capital city). It is the first large study of obesity in dogs in Denmark. 20.5% of the dogs were heavy or obese, corresponding to a body condition score of 7-9 on the nine-point Body Condition Score (5 is normal weight).

It’s not known why neutering is linked to male dogs being heavy/obese, but it could be that a reduction in testosterone due to neutering causes reductions in the basal metabolic rate. More research is needed to investigate this. Getting older was a risk factor for female dogs but not male dogs.

In contrast to previous research, this study did not find a link between the strength of someone’s attachment to their pet and the pet’s weight. However, there was a link between the owner’s and the pet’s weight. When the owner is overweight or obese, the dog is more than twice as likely to be heavy/obese than if the owner was a normal weight.

The researchers say part of the explanation is that overweight dog owners said they are more likely to use treats as “hygge-candy” (cozy-candy) than owners who are normal weight. In other words, they are more likely to give treats to their dog during relaxation times, e.g. as a snack or when the owner is eating. Treats given at other times (during dog training, trips to the vet, grooming/bathing sessions, or exercise) were not linked to the dog’s weight.
"Whereas normal weight owners tend to use treats for training purposes, overweight owners prefer to provide treats for the sake of hygge. For example, when a person is relaxing on the couch and shares the last bites of a sandwich or a cookie with their dog," says Bjørnvad. 

Owners with overweight or obese dogs may need to find ways to have an atmosphere of hygge – warmth, relaxation, and companionship – with their dog that does not revolve around treats. Earlier research has shown that owner behaviour plays an important role in helping overweight dogs and that specific strategies might be beneficial to help people get their dog’s weight down.

Overweight owners whose dog was heavy/obese reported walking their dog further than those whose dog was a normal weight, which is counterintuitive. It may mean they are trying to help their dog lose weight. Dogs that had opportunities to run off-leash were less likely to be heavy/obese, suggesting that exercise is important in maintaining a healthy weight.

This is a fascinating study and although correlation does not mean causation, it’s hoped these results provide ideas to help people to keep their dog’s weight at normal levels. The findings regarding spay/neuter surgery are especially interesting given that in Denmark, rates of spay/neuter are much lower than in north America.

Prof. Peter Sandøe, co-author of the study, says people
“might even want to consider not neutering. As long as there are no runaway females in the area, there are in most cases no reasons to neuter."
This idea may be controversial in north America, where spay/neuter is one of several factors thought to contribute to lower shelter euthanasia rates.
“Spay-neuter is so widely accepted in our country today that those who take exception to it are roundly chastised,” 
writes Alexandra Horowitz in the New York Times (excerpted from her new book Our Dogs, Ourselves: The Story of a Singular Bond). And yet, as this study suggests, neutering dogs may have other consequences.

This research definitely provides food for thought (but perhaps it’s not “hygge-food”). What strategies do you use to help keep (or get) your dog’s weight at a healthy level?

If you are concerned about your dog’s weight, speak to your veterinarian.

If you liked this post, check out my award-winning book Wag: The Science of Making Your Dog Happy. Modern Dog magazine calls it "the must-have guide to improving your dog's life."

Zazie Todd, PhD, is the award-winning author of Wag: The Science of Making Your Dog Happy and Purr: The Science of Making Your Cat Happy. She is the creator of the popular blog, Companion Animal Psychology, writes The Pawsitive Post premium newsletter, and also has a column at Psychology Today. Todd lives in Maple Ridge, BC, with her husband, one dog, and two cats. 

Useful links:

Bjørnvad, C. R., Gloor, S., Johansen, S. S., Sandøe, P., & Lund, T. B. (2019). Neutering increases the risk of obesity in male dogs but not in bitches—A cross-sectional study of dog-and owner-related risk factors for obesity in Danish companion dogs. Preventive veterinary medicine, 170, 104730.

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