What is pet obesity and why is it a problem
Pet obesity is defined as body weight 20% above optimal, causing diabetes, joint disease, and reduced lifespan in dogs and cats.
Excessive adipose tissue accumulation defined as body weight at least 20% greater than optimal, a condition that triggers metabolic changes and significantly increases the risk of orthopedic disease, diabetes, and cancer. This definition relies on a 9-point Body Condition Score (BCS) system where scores of 8 and 9 indicate obesity, rather than weight alone which varies too much between breeds.
Diagnosis relies on body shape, not just weight
Weight is a poor diagnostic tool because individuals within a species and breed vary significantly in size. The standard method is a 9-point Body Condition Score (BCS) where scores 1-3 are too thin, 4-5 are ideal, 6 is above ideal, 7 is overweight, and 8-9 are obese. This scoring correlates with true body fat percentage measured by DEXA scans, making it the most accurate non-invasive method available.
An ideally conditioned dog should have a tapered waist when viewed from above and a clear abdominal tuck from the side. Ribs should not be visible but must be easily palpated with only a very thin layer of fat cover. For cats, the ideal waist is visible behind the ribs with a slight fat pad over the ribs and a minimal abdominal fat pad.
Energy imbalance drives the condition
Weight gain occurs when an animal is in a positive energy balance, meaning calories consumed exceed calories expended. Middle-aged pets, particularly those between 5 and 10 years old, face an increased risk as their energy requirements decrease. For example, studies show that as cats age from 2 years to approximately 11.5 years, their energy needs drop, yet owners often fail to reduce food intake accordingly.
Excessive food intake and lack of physical exercise are the primary drivers. Owners frequently use food as a reward, leading to overfeeding, while pets confined to houses or small yards without regular exercise are prone to weight gain. In dogs, the owner's own weight is a risk factor; obese owners tend to walk their dogs less. In cats, neutering increases risk because altered sex hormones lower the basal metabolic rate and reduce the inclination to roam.
Management requires strict calorie control
Weight management involves two distinct phases: weight loss and weight maintenance. During the weight loss phase, energy intake must be strictly less than energy expenditure, a process that is challenging and where failure is common. If the animal cannot control its own intake, the owner must control the food amount using established energy allowance guidelines.
Medical interventions have existed but are limited. Drugs like dirlotapide (Slentrol) and mitratapide (Yarvitan) were approved to reduce appetite and food intake, with the FDA approving dirlotapide in 2007. However, these drugs have been withdrawn from the EU market, and up to 20% of treated dogs experience vomiting or diarrhea. Crucially, when treatment stops, appetite returns to previous levels, and without other strategies, the dog will regain the weight.
Health consequences are severe and systemic
Obese dogs and cats suffer a higher incidence of osteoarthritis and diabetes mellitus, often developing these conditions earlier in life than their lean counterparts. They also face increased risks of complications during anesthesia or surgery. Dogs may develop urinary incontinence, breathing difficulties, and a poorer quality of life with a lower life expectancy.
Cats face specific risks including diseases affecting the mouth and urinary tract. Obese cats that struggle to groom themselves are predisposed to dry, flaky skin and feline acne. The prevalence of this issue is high; in the United States, 23–53% of adult dogs are overweight or obese, while 55% of adult cats fall into this category. In Australia, obesity is the most common nutritional disease of pets, affecting approximately 40% of dogs.
The severity of the condition is recognized legally in some regions, with pet owners in the UK prosecuted for cruelty due to dangerously obese animals. The issue is significant enough that the US observes National Pet Obesity Awareness Day on October 14.