Obesity: Health risks and management in dogs and cats (Proceedings)


The number of animals that are overweight or obese has reached epidemic proportions in the US and other countries.

The number of animals that are overweight or obese has reached epidemic proportions in the US and other countries. It is the leading nutritional disease in pets of western societies. Identifying obesity and determining its cause is not a diagnostic challenge. Weight gain occurs when an animal is in positive energy balance for a prolonged period of time. Energy intake increases, energy expenditure decreases, or both happen concurrently. Although it is very common, and not difficult to understand, obesity is very difficult to treat.

Prevalence of Obesity in Dogs and Cats

The number of pets that are overweight or obese has reached epidemic proportions in the USA and other industrialized countries. There are various reports as to how common obesity is, but it has been shown that just over 35% of adult cats in the USA were overweight or obese. In addition, 45% of the cats aged 10-11 were considered overweight or obese. Studies investigating the prevalence of overweight/obesity in dogs have varied from 24% to 34%.

Obesity prevention in pets needs increased emphasis with focus on wellness plans through owner education. Significant health benefits to maintaining a normal to lean body weight have been shown in dogs and other species. The veterinary visit for spaying/neutering is an important, but often neglected, opportunity to reassess diet type and feeding management and make appropriate awareness of obesity issues to clients.

Risk Factors for Obesity in Dogs and Cats

1. Genetics

a. Dogs - Specific breeds are more likely to become overweight. These include but are not limited to Shetland Sheepdogs, Golden Retrievers, Dachshunds, Cocker Spaniels, Labrador Retrievers, Dalmatians, Rottweilers, and Mixed Breeds.

b. Cats -Mixed breed (DSH, DLH, DMH) and Manx cats were found more likely to be obese than most purebred cats.

2. Gender/neuter status-

a. Dogs - Neutered female dogs are about twice as likely to be overweight than are intact female dogs. Similar trends have been seen in castrated male dogs.

b. Cats - Male cats are predisposed to being overweight. Neutering further increases the risk of obesity by decreasing the metabolic rate by at least 25%. Removal of estrogens may also increase food consumption independent of the decreased metabolic rate. This may also be accompanied by an increased appetite following surgery.

3. Age- Risk increases with increasing age in both dogs and cats

4. Activity- Reduced activity increases risk for weight gain in both dogs and cats.

5. Food and feeding- Highly palatable foods, free choice feeding and excessive treats. In particular, feeding high fat foods is associated with obesity.

6. Other associations – In cats, other factors such as apartment dwelling, presumably due to decreased exercise opportunities - this is "softer" data, but seems to be a commonly observed association.

Health Risks of Obesity

Studies investigating overweight dogs and cats have identified many of the same health problems observed in humans. In cats, T2DM, neoplasia, dental disease, dermatologic diseases, and lower urinary tract problems have been associated with obesity. In dogs, overweight or obesity has been linked with diabetes, pancreatitis, cruciate ligament rupture, hypothyroidism, hyperadrenocorticism, lower urinary tract disease, oral disease, neoplasia dyslipidemia, osteoarthritis, hypertension, altered kidney function. In addition, although harder to measure, obesity exacerbates existing musculoskeletal problems, respiratory distress from upper airway obstruction, and pregnancy complications, and is associated with delayed wound healing, increased anesthetic/surgical risk, and probably reduced life expectancy. Obesity also makes tasks like collecting blood samples and placing intravenous catheters much more difficult.

Preventing or treating obesity may delay and or prevent many of these obesity-related diseases. A successful weight loss program requires a reduction in caloric intake (owner compliance) and an increase in physical activity. Weight loss studies in dogs have found positive associations on biomarkers associated with obesity-related diseases. Weight loss in dogs has been associated with a reduction in triglycerides, cholesterol, thyroxine and leptin. In addition, weight loss in dogs lead to an increase in insulin sensitivity and lowering of adipokines linked with insulin resistance (tumor necrosis factor alpha and insulin like growth factor-1).


Obesity prevention is where we should put the greatest emphasis. First, it's easier to prevent animals from becoming overweight than it is to treat. Secondly, there are significant health benefits to maintaining a normal to lean body weight. This should be a focus of a wellness plans, and client education efforts at the time of exams for kittens. Weight loss management programs can be an important part of your wellness program. Teach every owner to do a body condition score, and have them do so on a regular basis. Reinforce this at each kitten visit. The time a pet is scheduled for spay/neutering is an often neglected, but important time, for client education. Most owners are unaware that neutering will reduce their cat's energy needs. It's an important time to review the diet history (diet type, feeding management, etc) and make appropriate recommendations.

For kittens, owners should select a good quality commercial food that has undergone feeding trials according to Association of American Feed Control Officials (AAFCO) protocols for growth. Feeding directions are required on pet food labels but the quality of the information varies. Some feeding directions are very sketchy while others are quite detailed. Some feeding directions overestimate the amount of food a cat needs. Also, just like people, cats vary tremendously in how easily they gain weight. Therefore, the best method is to calculate the cat's energy requirements to come up with an estimate of the total number of calories required per day, as shown below, and then to feed to maintain optimal body condition (between 4 and 5 on a 1-9 scale).

RER= 70 x (BW in kg).75

MER= 2.0-2.5 x RER (feline growth)

1.2-1.4 x RER (intact adult cat)

1.0 x RER (neutered adult cat)

0.8 x RER (obesity prone adult cat)

Be aware that these are only starting points and the individual animal's actual MER may be higher or (often) lower. Once you calculate the MER, this number of calories is then divided by the caloric density of the selected cat food to determine the number of cups or cans to be fed each day. The number of calories in a particular pet food can be obtained from product guides, from the company's website, from calling the company, or for some foods, from the label. The pet food label is allowed to contain the calorie information but it is not required (except on "light" or "low calorie" foods – see below) so most brands do not list this information.

Calories/day ÷ calories per can or cup = cans or cups/day

This amount should be divided into at least two meals per day. Free choice feeding is fine for cats that can maintain optimal body weight but most indoor or indoor/outdoor cats need some control of calories to avoid becoming overweight. Be sure to talk to the owner about treats and table food as these can be a major contributor to obesity. Kittens should eat a food that has gone through feeding trials for growth until they are 1 year old. If they are becoming overweight before 1 year of age, they should be switched to a kitten food that is lower in caloric density but still meets the requirements for growth.

Developing a Weight Loss Program

If prevention does not work and the cat becomes overweight, a weight loss program must be designed to achieve the optimum body weight. The key to successful weight reduction is a comprehensive program - this means controlling the calories (from all sources), increasing exercise (if possible), and changing behaviors that contribute to obesity.

Animal Factors

Identify any underlying health problems that could contribute to obesity or will impact their ability to exercise. Start out with a thorough physical exam and do baseline blood work (liver enzymes and blood glucose are especially important). Identify medications taken that might affect appetite (steroids). Assign a body condition score (BCS), and estimate a target or realistic "ideal" weight.

Dietary factors

A thorough diet and feeding management history is critical. Ideally you would like enough information that you could go to the store and reproduce the animal's exact diet(s) and daily intake. The diet history should also include all snacks or treats. Consider having the owner complete a 3-day diet journal to document actual intake, and to account for a variable diet or unmeasured foods/treats.


Use the diet history to calculate the actual daily caloric intake. There are several different equations for calculating how much caloric restriction you want to implement to meet your goal. Cats are used as an example for calculations below.

There are two common ways to start

1. Use the diet history to calculate current intake and reduce intake from there. Even better, have the owner measure and record food intake for 3 days and use the average daily intake as the starting point. Feed 60-80% of the pet's current intake.

2. In the absence of a diet history, calculate the energy requirement at a realistic "ideal" body weight and feed to 60-80% of the goal energy requirement.

Target weight loss should be 0.5-1% of body weight per week for cats.

The initial weight goal should be reasonable goal for the owner (ie, for an 18 pound cat, a reasonable initial goal might be to lose 6 pounds). Owners can easily get discouraged if the initial goal is unreasonable. Also, if they are successful in the initial goal, they are much more motivated to continue. Also, in planning a weight loss program, aim for a conservative estimate of "ideal" body weight to avoid excessive restriction of calories. Extremely rapid weight loss in cats may result in hepatic lipidosis or protein deficiency. Do not exceed 1% body weight loss per week. During weight loss, protein level in the diet is important for maintaining lean body mass and helps to control diabetes (if the cat is also a diabetic) and prevent hepatic lipidosis.


Do not recommend continuation of the current diet in reduced amounts, unless the desired weight loss is very minimal (5% or less). Many cats will seem too hungry for this approach, and owners won't comply for long. Secondly, when the desired weight loss is more than that, nutritional deficiencies can occur with feeding a reduced amount of the same diet. Note that diets marketed as" low calorie" diets may not be very low in calories. There are AAFCO regulations on caloric content of low calorie pet foods. To be labeled as a "light," "lite," or "low calorie" cat food, the food must contain <3250 kcal/kg (dry food) or <950 kcal/kg for canned foods. In addition, foods labeled as such must include a caloric content statement. However, the requirement for the calorie statement is that it must be expressed as kcal/kg of food and may also be expressed as kcal/cup or kcal/can. Foods marketed as "weight reduction" diets can also vary tremendously in terms of caloric density. Accordingly, it is important to select a specific diet for overweight cats and to recommend a specific amount to feed (feeding directions often overestimate the amount of food required).

It is very important to maintain a high protein intake during weight loss in cats, both to help prevent hepatic lipidosis and to maintain lean body mass. It has been shown that heat production is higher in lean cats on a protein-rich diet. This means that cats on a high-protein diet burn more calories and gain less weight than cats fed a high-carbohydrate diet even with the same caloric intake. This indicates that replacing some of the carbohydrate or fat in a diet with protein could increase metabolism and promote weight loss. Therefore, select a weight reduction diet with relatively higher protein, L-carnitine, essential fatty acids, vitamins and minerals than in a maintenance diet to compensate for decreased caloric intake. Look for at least 45 % of calories from protein for cats. This will promote loss of body weight from fat rather than lean body mass. Ensure that diet selected will provide close to 2 g protein per pound of body weight at ideal weight.

There are many diets available for weight loss. Essentially they restrict fat to lower caloric density and "dilute' calories with air, water or fiber. The hypothesis for the use of fiber in these diets is to promote satiety. There are two published studies showing that increased dietary fiber decreased voluntary intake, while another study found the opposite results.

High protein/low carbohydrate diets are also advocated for weight loss – these have no magical properties and cats will not lose weight when eating them unless the total calories are sufficiently restricted. Some reduced calorie diets are low in fiber while others are high in fiber. The effect of fiber on satiety is controversial but high fiber diets may be useful, particularly in cats that appear especially hungry when on a weight reduction diet. Fiber content does alter fecal characteristics and owner preferences may dictate the type of diet selected. Diet changes should be made gradually, particularly when transitioning to a high fiber diet.

The owner must be instructed to measure the daily food allowance exactly to prevent overfeeding. Some owners are able to completely discontinue treats and table food but others will need recommendations for acceptable treats. If the owner would like to give treats, work with them to determine a reasonable number of treats/day and the calories provided by the treats should be subtracted from the amount of cat food recommended. Suggest high protein treats such as lean chicken pieces. Treats should make up no more than 5-10% of the diet, but make allowances in your calculations for treats. If you suggest total elimination of treats to some owners, you may lose credibility and owner compliance and openness.


Tailor the management plan to fit the family's individual needs and schedule. Recommend smaller feedings more frequently, suggest feeding the kibble in a play ball, such as Play-and-Treat. The family may consider abolishing all meals and feeding the daily ration as "treats" throughout the day (especially if owner works at home). Consider other pets in the house and ways to accommodate restricted feeding in light of this. Feed thin cats on the counter or refrigerator, where obese cats have trouble accessing. Separate pets for meals. Work with the owner to develop ideas for increasing exercise/activity. You may choose to delay exercise until some weight loss is achieved (for severe arthritis problems).


An important step in the success of a weight loss program is monitoring. There has to be owner accountability to increase the chance for success. Recheck every 2 weeks until a weight loss trend is achieved, then monthly for the next 6-12 months. Forewarn owners at the beginning that weight loss isn't linear. There will be plateaus, when the loss levels off and you may need to make adjustments in the feeding program. Also warn them about the maintenance phase. The goal isn't just weight loss, but maintenance of the new weight. This will take continued diligence on their part. They may not get to the target weight when together you decide to transition to a maintenance phase. The goal for weight reduction is rarely to achieve some cosmetic "ideal" BCS, but rather to reduce the morbidity associated with obesity and improve the quality of the animal's life. Rechecks are recommended every 3 months for 1 year to help support them through this maintenance phase. Note that even stable diabetics may have diabetic remission as a result of weight loss and/or a change to a high-protein, low-carbohydrate diet; therefore, clinical signs and blood glucose must be closely monitored during weight loss in diabetic cats.

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