Identify at-risk patients when battling obesity in companion animals

Small animals in North America are supplied with an abundance of highly nutritious and palatable food.

Concurrently, small animals live increasingly more sedentary lives, and clients provide treats and food as a basis for enhancing the human-animal bond. The result is frequently the consumption of excessive calories and the accumulation of adipose tissue.

The development of obesity can have numerous adverse effects on a patient's health, thus weight reduction in obese patients or weight stability in patients with an ideal body condition should be a focus of every veterinarian.

• The three "A's"

Patients that are at risk of becoming obese or that are obese should be entered into a weight loss program.

Successful weight loss programs should focus on three main areas that often are neglected.

Area number one is increased awareness both by the veterinarian and the client.

Area number two is accurate accounting of the patient's food intake.

Area three is assessment of the plan's ability to meet the patient's and the client's needs.

The following article will detail the application of these three A's in clinical practice.

• Awareness

Clients are frequently unaware of the presence and/or magnitude of their pet's obesity. Thus, the first step of any weight loss plan must be identifying the patient that is at risk of weight gain or in need of weight reduction.

Identifying Patients at Risk

Veterinarians regularly perform procedures that will increase the risk of a patient becoming obese.

Ovariohysterectomy and castrating have been shown to lead to increased food intake (Kanchuk et al. 2003). Orthopedic procedures frequently require exercise restriction initially and common drug therapies are known to cause polyphagia. Thus, potential iatrogenic energy imbalances should be identified and preventive adjustments in feeding strategies should be recommended.

In addition, certain breeds appear to be more commonly obese and certain clients appear to be prone to having a series of obese pets. Thus, identification of "at-risk" breeds for clients may be a valuable strategy to preventing obesity in patients.

Identifying Overweight Patients

A patient is overweight, using a human definition, when they are up to 20 percent more than its ideal body weight, and a patient is obese when it is 20-25 percent more than its ideal body weight due to adiposity.

There are numerous methods of quantifying a patient's body condition. The least accurate and potentially most subjective method is using a patient's body weight. Tables listing the "normal" weight range for dogs based on breed and sex do not account for the potential individual variation that can exist in breeds nor are similar tables fine enough to be useful in cats. Thus, the usefulness of body weight alone is quite low.

More sensitive methods such as bioelectrical impedance, stable isotope dilution, bromide dilution, DEXA and MR imaging are available, but their widespread use is inherently limited by cost and/or availability.

A more readily available technique is the use of a body condition scoring system (Laflamme et al. 1994).

Body condition scoring (BCS) uses both visual and tactile cues to assign a numeric value to a patient's degree of adiposity. The BCS has been validated to correlate with more complex measures of body condition such as DEXA. Since body condition scoring can be readily explained to clients, it is an effective tool to increase a client's awareness of a patient's degree of adiposity.

Many of the pet food companies have created posters and handouts that illustrate the appearance of patients at the different body condition scores. Most of these systems are based on either a 5 or 9-point system. Each subsequent point on the 5-point scale represents an increase or decrease depending on direction of 20-30 percent in body fat above or below ideal (i.e. 1 very thin and 5 obese). Each subsequent point on the 9-point scale represents an increase or decrease depending on direction of 10-15 percent in body fat above or below ideal (i.e. 1 emaciated and 9 grossly obese). Clients should be given a handout and shown where their pet falls on the chart.

The goal of any plan should be the improved health of the patient.

For some patients this may not be the return to an ideal body weight, but instead the reduction in clinical signs associated with some disease process or a reduction in risk for the development of disease.

It must be remembered that a weight loss plan that achieves any weight reduction has inherently been successful. Weight loss can be quite difficult to achieve in some patients and/or be very slow, thus, even slight weight reductions should be celebrated.

• Accurate accounting

Once a client recognizes that his or her pet is overweight and may benefit from weight loss, there is a potential for the development of guilt and concern that the veterinarian will blame him or her for their pet's weight.

The main effect of this guilt is a lack of accurate accounting of a patient's complete daily/weekly diet.

Unfortunately, patients vary greatly with regard to energy requirement for weight stability (presented in Lewis et al. 1987); thus, if you receive an inaccurate or incomplete diet history from the client, there is an increased risk that recommendations for amounts to feed will result in weight gain, weight stability or weight loss at too rapid a rate. This is due to the inherent variability in energy requirement for the individual patient. The best method is to use the patient's current caloric intake to make recommendations.

Caloric Intake for Weight Loss

Eighty percent of current caloric intake

(Table 1). Note, if the calculation results in a value below 50 percent of RER (RER = 70 x BWkg3/4), a careful review of the patient's health status (blood work, physical) and the accuracy of the diet history should be undertaken. Severe caloric restriction can result in both metabolic rate and activity changes that may prevent weight loss without concurrently making a patient extremely lethargic.

Table 1 Recommendations for Caloric Restriction by Company (Assumed 10 lb. cat and 20 lb. dog with a BCS of 8/9)

Most patients undergoing weight reduction should be at least as active as they were prior to the initiation of the plan or more often they will be more active.

In addition, special care must be made in cats to ensure that weight loss is not so rapid as to increase the risk of developing hepatic lipidosis. An obese cat should never be allowed to become anorexic under the pretext that it will be beneficial for weight loss. Anorexia in an obese cat should be closely monitored. The risk of developing hepatic lipidosis should be discussed with the client at the start of any weight loss plan.

Weight Loss Rate

The rate of loss (usually 1-2 percent of body weight per week) is based on traditional clinical recommendations that were designed to maintain lean body mass and preferentially burn fat mass.

In addition, it appears that the slower the rate of weight loss, the less the body responds by slowing the metabolic rate and the less hungry the patient seems. Thus, a slower rate of weight loss potentially decreases the likelihood of weight rebound and increases the likelihood of client compliance.

Often, patients with the most compliant of clients will not lose greater than 0.5 percent of their body weight per week. If the patient is doing well and the client is not impatient, this level of loss should be accepted and further caloric restriction is not necessary.

It must be remembered that there can be a great deal of variation in the energy requirement of a patient. Even with the most accurate diet history and most compliant client, there will be times when the patient's response to the weight loss plan will be poor. An assessment of a patient's response must be made with corresponding adjustments based on the response.

• Assessment

Since patients may respond to the weight loss plan in unpredictable ways, reassessing the patient's response is vital to any successful plan. Adjustments in the quantity of diet being fed needs to be made based on response.

There is often a temptation to starve the animal to achieve "guaranteed" weight loss, but this is not in the best medical interest of the patient, nor is it likely to lead to long-term successful weight loss and/or compliance.

Weigh-Ins

Reweighing patients serves two main functions.

First, it allows adjustments to be made in the weight loss plan based on response. Second, it allows for more frequent success.

Since the majority of patients will not show any visible signs of weight loss for several months, the client may become disenchanted and less resolved to continue. However, if the client can see quantifiable changes in the patient's weight, it can help reinforce his or her commitment to the weight loss plan. It also can serve as a clear indicator to the client whether the restriction is appropriate or not.

Weigh-ins also provide the best method to adjust the level of restriction for a particular patient. Without weigh-ins, weight loss plans are often doomed to failure due to inaccurate initial recommendations.

Commercially Available Therapeutic Diets Designed for Weight Loss

Numerous dietary strategies have been employed in the design of therapeutic weight loss diets.

With the exception of a couple of "low carb" canned feline weight loss diets, all diets have a decreased energy density (i.e. kcal per unit volume) compared to most "light" or maintenance diets. Decreased energy density, hopefully, increases satiety by gut fill and also client compliance.

"Low carb" diets may alter the pet's metabolism to increase fat catabolism.

Probably the most important formulation difference of weight loss diets is an increase in the essential nutrients per kilocalorie. Ideally, the only nutrient being limited during weight loss would be energy. A patient's requirement for protein, fat, minerals and vitamins does not decrease during weight loss. Thus, limiting intake of essential nutrients would be inappropriate. Therefore, the selection of a weight loss diet is not solely for decreased energy density, potential satiety and/or changes in metabolism, but also for deficiency prevention. A list of available diets designed and marketed for weight loss is found in Table 2.

Table 2

Feeding Frequency

Increasing the frequency of meals may assist with decreasing the problem of begging.

This may be due to a satiety effect or more likely will provide the client with an allowed and accounted for meal during times of begging.

Increasing the frequency of meals may also lead to better compliance because although the volume for any given meal is less, the client feels the pet is fed more due to the increased meal frequency.

Treats

Providing clients with treats is important for compliance to weight loss plans.

If treats are not included in the plan, they most likely will still be provided, but not accounted for, making appropriate adjustments in caloric intake more difficult.

Incomplete and unbalanced treats should be limited to 10 percent of caloric intake to prevent deficiencies from developing.

Excellent low-calorie human foods that can be used as treats are baby carrots, air-popped popcorn and unflavored rice cakes. Even high fat treats can be used, but careful instructions on the limited amount that can be fed must be given to the client (this also allows you to educate the client on energy density differences between foodstuffs.)

Suggested reading

Exercise

Exclusively relying on calorie restriction may not be the best means of achieving weight loss. Caloric restriction, coupled with exercise, has the benefit of increasing the patient's metabolic rate and assisting with lean body mass maintenance. In addition, exercise provides an alternative method of reinforcing the human-animal bond that does not rely on treats or meal feeding.

Exercise can be instituted by simply increasing/creating play time(s) or taking the pet on walks.

Weight Maintenance Following Weight Loss

It is important that once a patient successfully completes a weight loss plan that they also successfully maintain their new weight. Care should be taken when the patient is weaned onto a new diet and a new caloric intake.

Numerous weight management diets are available over-the-counter. These diets fall into two categories: "light", "lite" or "low calorie" and "less calorie", "reduced calorie", "lean", "low fat", "less fat" or "reduced fat". Only the first group of terms gives information on energy density. The other group of terms does not provide any insight on the energy density of the diet.

Initially, feeding should start with a slow transition to the new "light" diet over five to seven days at the same number of calories that the patient was on at the end of the weight loss plan. Slowly the patient's caloric intake is adjusted based on weigh-ins until the patient has achieved weight stability.

Dr. Delaney is the principal consultant for Davis Veterinary Medical Consulting, P.C., which specializes in nutritional consulting for the petfood industry. He is a diplomate of the American College of Veterinary Nutrition and is a lecturer in clinical nutrition at the Veterinary Medical Teaching Hospital at the University of California, Davis.

Disclosure: Owner of Consulting Prof. Corp.