Glossary

Obesity

Excess body fat that shortens lives and raises the risk of arthritis, diabetes and other disease; it is the most common nutrition problem in pet dogs.

Also called: overweight dog, fat dog, canine obesity, dog weight loss, dog weight gain, overweight

Obesity means carrying enough body fat to harm health, usually defined as a body condition score of 8 or 9 on a 9-point scale. Surveys estimate that more than half of dogs in the United States are overweight or obese, and breeds such as the Labrador Retriever and Beagle gain easily.

Extra weight stresses joints and the heart, raises the risk of diabetes, some cancers and heat intolerance, and reduces exercise ability. A long-term study of Labrador retrievers found that lean dogs lived nearly two years longer than their overweight littermates.

Causes are mostly too many calories and too little activity, though hormone problems can contribute. Ask a veterinarian before putting a dog on a diet, because crash diets and unplanned changes can harm them, and a vet can rule out disease and set a safe target.

Last reviewed November 8, 2026

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Related terms

Body condition score A hands-on rating of how lean or fat a dog is on a 9-point scale, more reliable than weight alone, with 4 or 5 as ideal. Calorie The unit of energy in food; dog food labels list kilocalories per cup or kilogram, which is how portions and weight are controlled. Osteoarthritis A long-term, painful wearing down of joint cartilage that causes stiffness and reluctance to move, common in older and overweight dogs. Diabetes mellitus A disease in which the body cannot make or use enough insulin, so blood sugar stays high, with increased thirst and urination.