Why Are Some Dog Breeds More Prone to Obesity?

Written by:

Ken Tudor, DVM
Published: February 07, 2014

Obesity is the number one nutritional disease affecting pets today. Its relation to arthritis, cardiovascular disease, diabetes, and decreased life span make it a serious medical condition. Breed is a known risk factor in dogs and official breed descriptions may promote this obesity risk factor.

Risk Factors for Obesity in Dogs

Aging and sexual neutering have long been known to increase the risk of obesity in pets. Activity levels decrease as pets age. Arthritic changes associated with aging further decrease activity. Decreased activity levels reduce dietary calorie requirements. Without adjustments in meal portions, older animals easily put on extra fat. Sexual neutering reduces calorie requirements by as much as 10-20 percent.

Pet owner socio-economic status also poses a risk. Pet pampering is much easier with increased wealth. The owner's lifestyle and own body condition are other non-pet related risk factors.  

Breed as a risk factor is less understood. Overweight Golden and Labrador Retrievers and Newfoundlands are the norm rather than the exception. Cocker Spaniels, Pugs, and Bichons have the same tendency. Yet, Whippets, Boxers, and Setters maintain a more ideal body condition.

So, why does breed make a difference? A new study suggests that the wording of breed standards may be a contributing factor. By breeding to specific standards, genetic selection may favor the risk of the overweight or obese condition.

Results of Research on Overweight Dog Breeds

Dutch veterinary researchers collected Body Condition Scores (BCS) of 1,379 dogs at a Netherlands dog show. All scores were assigned by the same board certified veterinary nutritionist using the 9-point scale. The BCS is a visual and palpation (touching) system of ranking a pet’s fitness. Pets are observed and examined from the side and above, looking from the back toward the head. Scores 1-3 are pets that are too thin and underweight. Scores 4-5 are considered ideal. Scores 6-9 represent various stages of overweight. Most veterinarians agree that scores of 8 and 9 represent obese pets. The simple BCS system has proven to correlate with body fat measurements obtained from sophisticated X-ray technology (DEXA). The system works for both dogs and cats.

The researchers then analyzed average BCS scores against breed show standards. They found that the average BCS correlated to the language used to describe the breed.

Language for dogs with a lower BCS include “elegance,” “smoothly muscled body,” “graceful,” and “athletic.”

Language for dogs with a higher BCS include “muscular,” “heavier in bone,” “massive build,” “square and thick set in overall build,” “dogs are more massive throughout,” “square and cobby,” and “bold and valiant figure.”

These expressions definitely conjure different visions. So, how does this language promote obesity?

The "Thrifty" Genotype in Dogs

The researchers in this study point out that dog breeds were initially selected for specific purposes. Colder climates required more fat for insulation and nutritional reserves, or what is called the "thrifty gene." These dogs no longer labor under adverse conditions. With an ample supply of calorie dense diet (dry kibble), selection for the thrifty gene has turned into a risk factor for obesity. The breed standard language perpetuates the body type associated with the thrifty gene.

The researchers stop short of suggesting changes in the wording of breed standards. Instead they suggest that breed standards can predict the risk factor for obesity. By identifying risk, breed can be used to promote prevention rather than as an excuse for ignoring treatment.     

Dr. Ken Tudor

Image: lenetstan / Shutterstock