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

Abstract

OBJECTIVE To examine the risk of developing an overweight or obese (O/O) body condition score (BCS) in gonadectomized versus intact dogs and, separately, the impact of age at gonadectomy on O/O outcomes among sterilized dogs. ANIMALS Dogs were patients of Banfield Pet Hospital in the US from 2013 to 2019. After exclusion criteria were applied, the final sample consisted of 155,199 dogs. PROCEDURES In this retrospective cohort study, Cox proportional hazards models evaluated associations between O/O and gonadectomy status, sex, age at gonadectomy, and breed size. Models were used to estimate the risk of becoming O/O in gonadectomized versus intact dogs and, separately, to estimate risk of O/O BCS according to age at surgery among gonadectomized dogs. RESULTS Gonadectomy increased O/O risk for most dogs compared to intact dogs. Unlike most prior findings, O/O hazard ratios among gonadectomized versus intact dogs were larger for males than females. O/O risk varied according to breed size but not linearly. Sterilizing at 1 year old tended to yield a lower O/O risk compared to doing so later. Comparative O/O risk among dogs gonadectomized at 6 months versus 1 year varied by breed size. Overall patterns for obesity related to size were similar to patterns in the O/O analysis. CLINICAL RELEVANCE Veterinarians are uniquely positioned to help prevent O/O in their patients. Results extend understanding of risk factors for O/O development in dogs. In combination with information about other benefits and risks associated with gonadectomy, these data can help tailor recommendations regarding gonadectomy in individual dogs.

Body weight, gonadectomy, and other risk factors for diagnosis of osteoarthritis in companion dogs

“…Owners of dogs in this population were offered various wellness plans, which consist of prepaid packages of services that can reduce the cost of clinic visits and some diagnostic tests, including radiographs. Enrollment in such a wellness plan has previously been suggested to be a risk factor for detection bias ( 38 ), and in this study, it was strongly associated with OA diagnosis. Dogs with a wellness plan had far more clinic visits and were more likely to have radiographs than dogs not enrolled in such a plan (data not shown), likely leading to a higher rate of detection of OA.…”

“…Both weight and desexing are independent risk factors of OA. However, it has been reported that dogs that are desexed may be more likely to develop obesity ( 22 , 38 ), which may increase the risk of OA. To test if the influence of higher body weight on OA-free survival differed by desexing status, the interaction between adult weight and desexing status was tested.…”

“…Neutering is also an established risk factor for obesity ( 16 , 22 , 23 , 38 ), and it is possible that one way in which neutering increases OA risk is by increasing the propensity for overweight and obesity. Because of challenges in the interpretation of BCS scores, it was difficult to compare the occurrence of overweight and obesity between intact and neutered dogs.…”