Current Concepts


Obesity is one of the most common health problems affecting pets, with up to 59% of dogs and cats being overweight. Body condition scoring (BCS) should be performed on every patient and only be used to assess body fat, while muscle condition scoring should be used to quantify muscle wasting (for example, an obese pet, which would be a BCS 9 on a 9 point scale, could also have severe muscle wasting). Obesity has been associated with numerous diseases, including pancreatitis, osteoarthritis, dermatologic disease, diabetes, certain types of neoplasia, and respiratory tract disease. In addition, one major study showed mild to moderately (BCS 6-7/9) overweight dogs had shorter median lifespans than their leaner counterparts (BCS 4-5/9). Obesity is more easily prevented than treated and the veterinarian plays an important role in educating clients before a pet becomes obese.

Clinical Considerations:

Owners should be made aware of the increased costs associated with having an overweight pet, which can include food, preventative care, medications and associated comorbidities. Obese patients undergoing anesthesia may be at higher risk and should be monitored carefully. Drug dosages are particularly of importance when using medications with a narrow safety range, such as some chemotherapeutic and immunosuppressive medications, and each patient and medication must be considered on an individual basis.


Proper feeding and body condition should be discussed at initial puppy and kitten visits. Pets should not be fed an adult food until at least one year of age and a lower calorie puppy or kitten food should be selected if needed. In many pets, energy requirements decrease as much as 20% or more after spaying or neutering, so reducing intake and assessing body condition one-two months after surgery is recommended. The same applies to yearly visits, where proper body weight and condition should be reinforced. Feeding directions, even on foods marketed for weight management, can grossly overestimate energy requirements, so owners should always feed to an ideal body condition and switch to a lower calorie diet if their pet needs to eat much less than the directions suggest.

Initial Assessment and Weight Management Plan:

A complete diet history should be obtained to allow for an accurate estimate of daily caloric intake. Many owners are not aware that supplements, treats, rawhides or dental chews contain calories. Two strategies for determining starting calorie amounts are to restrict to 80% of current intake if known, or feed at the calculated resting energy requirement (RER: 70 x BW(kg)0.75) for estimated ideal weight. More important than the starting amount are frequent weigh-ins to ensure safe and effective weight loss of 1-2% of initial body weight per week. Owners should also be encouraged to increase their pet’s physical activity gradually, and many veterinary physical rehabilitation services are available that can help improve strength and mobility while limiting the risk of further injury. Techniques for encouraging exercise in cats can include food dispensing toys, feeding multiple small meals in different parts of the house, feather toys, or laser pointers.

Diet Selection:

Weight loss diets should contain an increased nutrient/calorie ratio to avoid risk of deficiencies, adequate protein to avoid malnutrition, and a low caloric density (kcal/cup or can) to increase total volume of food. While many cats and dogs do well on high fiber diets with increased satiety, some may have gastrointestinal side effects that owners should be aware of, and transitions should be gradual. The addition of L-carnitine or omega 3 fatty acids has limited adverse effects, but further research is required before widespread supplementation can be recommended. Over the counter ‘weight management’ diets are often not ideal as they vary considerably in calorie density and may not contain adequate amounts of essential nutrients when restricted to the amounts necessary to achieve weight loss. The optimal nutrient profile for a weight loss diet should be based on the preferences and lifestyle of the owner and the pet. Compliance is critical in weight management, so paying particular attention to owners’ concerns will increase the chance of success.


If owners feel treats are important, compliance may be increased by allowing treats, but they should be limited to 10% of the total calorie intake. Non-starchy vegetables such as carrots or celery are excellent low calorie treats.  Alternatively, a small portion of the daily allotment of food can be given throughout the day as treats.

Follow Up:

Food amounts should be adjusted until one percent body weight loss per week is seen except in dogs and cats with comorbidities, for which a more gradual rate of loss (0.5%) is recommended. Once ideal weight has been reached, the majority of cats and dogs will continue to need caloric restriction and lifelong monitoring.

Psychology of Obesity:

The complex relationship between owners and their pets must be understood in order to achieve successful weight loss. Educating owners on ideal body condition, health consequences, and appropriate feeding is an initial step. Owners often cannot identify their pet’s body condition and even those who score their pet’s condition above optimal still might not consider their pet overweight. Beyond acknowledgement of BCS, owners should also be educated on appropriate feeding methods. Many owners do not measure their pets’ allotment of food and may be giving much larger serving sizes than they are aware. Pet obesity is a multi-factorial, highly complex condition that requires intensive and active efforts on behalf of both the owner and veterinarian.


Obesity is common in cats and dogs and can lead to serious health consequences. Prevention of obesity is best done by educating owners and assessing body condition during growth and at yearly wellness visits. When a patient is overweight, thorough assessment of the current diet, and acknowledgement of potential challenges and concerns of the owner are necessary to form a successful weight loss plan. Feeding a purpose-formulated diet with an increased nutrient:calorie ratio is recommended in most cases to achieve a gradual one percent weekly rate of body weight loss. Follow up with patients, adjusting the program, and working with owners to increase compliance are crucial for success.