Canine Obesity: The Physical Condition of Dogs Undergoing Sterilization Has a Significant Impact on Their Lifespan

The effects of excess weight on longevity were studied in middle-aged, spayed or neutered dogs belonging to twelve popular dog breeds, who were monitored by a veterinarian and their owners. Conducted in North America, this retrospective case-control study collected data from approximately 900 veterinary hospitals over a 20-year period. The results show a negative association between being overweight and lifespan in pet dogs. The authors emphasize the need for veterinarians to encourage their clients to monitor their dogs’ body condition, particularly for dogs aged 5 to 9 years, in order to prevent the development of canine obesity, the prevalence of which continues to rise.   Overweight or obesity is now a major health problem in dogs. Indeed, the growing number of overweight or obese dogs is associated with an increased risk of developing various chronic diseases, a high mortality rate, and a reduced quality of life. The study on canine longevity compiled clinical, demographic, and geographic data from a vast network of North American veterinary clinics—primarily located in the United States—over a period spanning 1994 to 2015. More than 50,700 dogs of average age (5.5 to 9.5 years), who were treated at these clinics, were included in the study. The researchers identified significant differences in life expectancy among dogs undergoing sterilization, male and female, of twelve dog breeds (American Cocker Spaniel, Beagle, Boxer, Chihuahua, Dachshund, German Shepherd, Labrador and Golden Retriever, Pit Bull, Miniature Spitz, Shih Tzu, and Yorkshire Terrier), representing five size classes. For each breed, the median lifespan was calculated, and the dogs were divided into two groups based on their body condition: “overweight” or “normal.” Within each group, differences in life expectancy based on body condition were analyzed for each of the twelve breeds. For all breeds, the risk of mortality among overweight dogs was higher than that of dogs of normal body condition (risk ratios ranging from 1.35 for German Shepherds to 2.86 for Yorkshire Terriers). Similarly, average life expectancy was shorter in overweight dogs compared to dogs of normal weight, with the extent of this difference varying depending on the size of the breed in question : survival was longest among Yorkshire Terriers (13.7 years when overweight, 16.2 years at a normal weight) and shortest among German Shepherds (overweight: 12.1 years, normal weight: 12.5 years). Thus, the study demonstrates a significant effect of being overweight on the lifespan of pedigree dogs. These findings should encourage veterinarians to prevent the development of obesity in their clients’ dogs . In particular, veterinarians could use these findings during an initial consultation with puppy owners to highlight the health risks their pets face as adults and the need for preventive care. The findings could also be used to convince owners of dogs that are already obese of the need to implement a supervised weight-loss program. According to the authors, although only a dozen dog breeds were studied, the fact that the negative association between excess weight and lifespan was observed in all twelve suggests that the same effect is likely to hold true for other breeds. Nevertheless, such extrapolations should be made with caution until studies involving a broader range of breeds are conducted. Similarly, the inclusion of dogs subject to sterilization or aged 5 to 9 years means that extrapolation to sexually active or younger dogs remains to be explored. Furthermore, additional research is needed to determine the causes of the difference in life expectancy between overweight or obese dogs and those of normal weight. This is because, in this study, being overweight was only indirectly associated with longevity—for example, by predisposing dogs to fatal diseases (neoplasia) or by exacerbating conditions that negatively impact their health (osteoarthritis).