A cross-sectional study was performed to identify the prevalence and associated risk factors of overweight and obesity in the adult canine population of the United States. A total of 21,754 dogs were included in this analysis, taken from data collected by U.S. veterinarians during 1995. The adult dog population was defined as dogs older than 1 year of age. Analyses were performed on adults having > 1 diagnosis of any kind, and body condition score (BCS) was recorded > 1 time during the study period. Obese dogs were defined as having an average BCS > 4.5 on scale of 1 to 5. Overweight dogs were defined as having an average BCS > 3.5 and < 4.5. Variables examined in the study included age, breed, gender, neuter status, food type, concurrent disease, and geographic region of residence. The study found that 34.1% of the dogs were overweight or obese (5.1% obese, 29.0% overweight). Prevalence was greatest in middle-aged dogs (around 6 to 10 years of age) as well as in neutered males and spayed females. Intact males had the lowest prevalence of overweight and obesity. Certain breeds were more likely to be overweight (cocker spaniels, Labrador retrievers, dalmatians, dachshunds, rottweilers, golden retrievers, Shetland sheepdogs, and mixed breeds) and obese (Shetland sheepdogs, dachshunds, and golden retrievers). Overweight dogs were more likely to eat semimoist food as the major part of their diet and were more likely to live in the Pacific, South Central, East North Central, or Northeast United States; they were also more likely to be diagnosed with hyperadrenocorticism, ruptured cruciate ligament, hypothyroidism, lower urinary tract disease, or oral disease. Obese dogs were more likely to consume "other" foods (meat, commercial treats, or table scraps), homemade food, or canned foods as the major part of their diet. They were more likely to live in the Pacific or Northeast United States and to be diagnosed with hypothyroidism, diabetes mellitus, pancreatitis, ruptured cruciate ligament, or neoplasia. The authors suggest that this study provides important descriptive data on obesity as well as evidence that promoting weight reduction in overweight and obese dogs may reduce morbidity.

COMMENTARY: The problem of obesity and its relationship to certain diseases in humans is well-known. It stands to reason that similar relationships exist in the canine population. This study illustrates both the degree to which overweight and obesity have become a problem in dogs in the United States and defines the relative risks associated with it. By examining these data, practitioners might be better able to target pets at greatest risk and utilize this information to counsel clients, for instance by providing nutritional counseling at the time of spay/neuter, providing extra guidance to pets fed diets more closely associated with overweight/obesity, or counseling owners of at-risk breeds to be extra vigilant at maintaining a healthy weight. Future studies of both dogs and cats that would further identify risks, and possibly define actual causal relationships between weight and specific disease states, would be very useful.

Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. Lund EM, Armstrong PJ, Kirk CA, Klausner JS. Intl  J Appl Res Vet Med 4:177-186, 2006.