Research Examines Link Between Dog Sterilization and Obesity Rates

In the U.S., approximately 70–80% of dogs are sterilized, a practice that helps reduce unwanted breeding, according to Valerie Benka, Program Director at the Alliance for Contraception in Cats & Dogs, and a member of the research team. Despite the benefits, concerns remain regarding the health and behavioral effects of sterilization.

Benka noted that there are concerning obesity rates among dogs in the U.S. and other countries, leading to negative consequences for their health and longevity, which can also contribute to other health issues. The findings show that sterilized small dogs are at the highest risk of obesity, while giant breeds exhibit the lowest risk. Interestingly, larger breeds such as Labrador retrievers, German shepherds, and golden retrievers have obesity rates that resemble those of smaller dogs.

The timing of sterilization also significantly affects obesity risk, with sterilizing dogs at one year of age generally associated with a lower risk. However, the optimal timing varies depending on the dog's breed size. Notably, large dogs sterilized at three or six months face an increased risk of obesity.

Additionally, the study found that when controlling for factors like breed, size, and age at sterilization, males are at a higher risk of obesity compared to females, which contradicts common assumptions about weight predisposition.

This research stands out for utilizing a comprehensive dataset of over 155,000 dog records from U.S. Banfield Pet Hospital clinics, including both purebred and mixed-breed dogs and differentiating between mixed-breed sizes, thus offering a representative sample of the canine population.

Benka expressed gratitude to the Morris Animal Foundation for supporting the research, which includes collaboration with a statistical data analyst and the ability to publish findings openly.

The research team, led by Benka, aims to publish further analysis on specific breeds and will investigate the links between sterilization, obesity, and cranial cruciate ligament injuries in dogs.

Publication details: Valerie A. Benka et al, Age at gonadectomy, sex, and breed size affect risk of canine overweight and obese outcomes: a retrospective cohort study using data from United States primary care veterinary clinics, Journal of the American Veterinary Medical Association (2023). DOI: 10.2460/javma.22.12.0596.