See spot run: obesity doesn't have to be permanent

SEE SPOT RUN: OBESITY DOESN’T HAVE
system uses both visual cues and palpation of specific TO BE PERMANENT
areas (the ribcage, waist, and dorsal spinous processes) to estimate subcutaneous and abdominal fat Debra L. Zoran, DVM, PhD, Diplomate ACVIM accumulation relative to superficial muscles. This technique is highly precise (repeatable), but not Texas A&M University, College Station, TX necessarily accurate. However, it is currently the most well known and repeatable means of body condition Obesity is the excessive accumulation of adipose score assessment in the clinical setting and should be tissue in body, and has been defined to occur when used as part of the physical examination of all pets dogs or cats are >30% over their optimal body weight. In humans, criteria have been established for what defines “overweight” and what is “obese,” and these criteria have THE CAUSES OF OBESITY
generally been based on the body mass index. However, The primary reason for development of obesity in any no similar index for optimal body weight has been animal is that they are consuming more energy than they identified in dogs and cats, and thus the use of these are expending. This can occur when a dog has classifications has not been rigorously studied. However, excessive dietary intake of calories (food and treats) or in general, dogs are reported to be overweight when when there is a reduction in energy expenditure their body weight is 15% over their optimal body weight, (reduced activity, illness or injury resulting in less and obese when they are >30% over the optimum. exercise, etc). There are some medical conditions and Using these criteria, the incidence of obesity in dogs and cats in the United States is reportedly between 30% and endocrinopathies, such as hyperadrenocorticism and 40%. More alarming, however, is the suggestion that the hypothyroidism, and drugs such as steroids and incidence of obesity in our pet population is increasing anticonvulsants. But the primary reason that weight gain despite the many attempts to control weight with diet and occurs in dogs on steroids or with hypothyroidism is that exercise programs. This article reviews our current they have either increased food intake or decreased understanding of obesity in dogs, its important role in the energy expenditure (or in some cases, both). development of many diseases in dogs, and discusses Nevertheless, in both instances, the primary reason for the approach to management of obesity from dietary, the development of obesity is still a positive energy lifestyle and behavioral alterations to newer balance. While genetic factors are also likely involved pharmacologic options for management. (eg, Labrador retrievers have a higher incidence of obesity than is seen in other breeds of like size), the role DEFINING AND MEASURING OBESITY
of inheritance in canine obesity needs more study. In The first step in the evaluation of a pet that is both dogs and cats, neutering is an important risk factor overweight or obese is to make an assessment of the due to the hormonal changes that occur that result in degree of the problem. Assessment of body changes in levels of leptin, progestins, and other composition, or more specifically, attempting to separate hormones that result in increased appetite, and reduced fat mass from the lean body mass, has been energy metabolism and metabolic rate. The key factors approached by a wide variety of different methods; for prevention of obesity in neutered animals appear to unfortunately, none are ideal. The key is to find be careful control of intake immediately after neutering assessment methods that are precise, accurate, easy to (no free choice feeding, reduction of intake by 25% to do in a practice setting, and not excessively costly. account for the hormonal changes resulting in reduced However, many of the tests are precise, but not accurate energy needs), and close monitoring of body weight and (able to yield the same result on repeated analysis, BCS to allow adjustments in intake if needed. In dogs, irrespective of accuracy), and others lack both precision there are a number of dietary factors that are also and accuracy. The most precise and accurate tests that associated with obesity, including the number of snacks are used in research settings are costly, not easy to use fed, especially table scraps, and the number of meals. and are invasive, and thus are not ideal for clinical Dogs that were allowed to be near their owners at practice. Examples of the most common research tools mealtime also had a greater tendency to be obese due used for assessment of body composition include to the increased likelihood of receiving table scraps and chemical analysis, densitometry, dual-energy x-ray human food treats. In addition, because feeding dogs is absorptiometry (DXA), subcutaneous or visceral a social interaction, feeding and food interaction with the ultrasonography, CT or MRI. Thus, in the clinical setting, dog can become a daily social interaction that can the most widely used procedures to assess body become a problem resulting in overfeeding and composition are measurements of body weight or inappropriate food intake patterns. It has been shown morphometric measurements (eg, body condition that in households where the owners are health scoring, tape measurements or body mass index). conscious (conscious of diet and nutrition, who exercise Morphometry or the measurement of form is used to regularly, and watch their own weight) they tend not to assess body composition using different parameters that have obese dogs. Thus, there are clearly human can be measured. Body condition scoring (BCS) behavioral and “food is love” issues that have to be employs a subjective method of quantifying the body considered in the development of obesity in dogs, and composition based on 5-point or 9-point schemes. This The North American Veterinary Conference – 2007 these must be addressed for successful weight control to Dietary Therapy
There are two important goals in establishing an appropriate dietary therapy regimen: 1) It must be THE IMPORTANCE OF OBESITY AS A DISEASE
tailored to the individual animal (diet needs for allergy, Obese humans generally do not live as long as their renal disease, GI issues, etc), and 2) caloric restriction lean counterparts, and are much more likely to suffer must occur without concurrent protein starvation to from obesity-related diseases such as type II diabetes, prevent loss of lean muscle tissue during weight loss. coronary artery disease, osteoarthritis, hypertension, The first step in making a diet plan is to obtain a and some cancers. Dogs and cats are susceptible to the complete dietary history that gives an accurate same detrimental effects, including decreased longevity, accounting of all foods fed to a pet on a typical day. In and development of a variety of disorders that are some cases, it may be necessary to have the owners associated with being obese. In a recent study, dietary keep a diet log for a week, writing down the meals, the calorie restriction was clearly shown to increase treats, the table foods, etc. consumed by the dog during longevity in a group of 24 Labrador retrievers. In that that time. This is especially helpful in households where study, the dogs in the energy-restricted group were fed the dog may receive foods from more than one individual 75% of their counterparts, and the dogs lived an average (especially children). In addition, it should be noted if the of two years longer and had a reduced incidence of hip dog has access to any other foods (other pets in the dysplasia, osteoarthritis and glucose intolerance. Other family, outside scavenging), if the pet received problems that were found to be more common in obese medications in foods, and if there are other food items dogs compared to the dogs that were of ideal body available to the dog (chew treats, dental chews, etc). condition include heat intolerance, increased anesthetic The next step in designing a diet plan is to decide risk, increased difficulty with routine clinical procedures upon a weight loss goal. The goal does not necessarily (catheter placement, palpation, imaging), and prolonged have to be that the pet achieves its ideal body weight – this goal should be based on the pet, the owner’s There are a number of diseases in dogs and cats are situation and goals, and the ability to reach the goal. It is reported to be associated with obesity, including important to set reasonable goals that can be achieved, orthopedic diseases, diabetes, heart disease, abnormal rather than overly ambitious goals that are not likely to circulating lipids, certain cancers, urethral sphincter be achieved and result in the client becoming mechanism incompetence, dyspnea due to discouraged because their pet is not meeting the compromised ability to breathe (eg, laryngeal paralysis, expected goal. A step down approach to weight loss is brachycephalic syndrome, tracheal collapse etc), heat much more likely to result in success and continued intolerance, decreased immune function, and dystocia to owner persistence, than a goal that is too ambitious and name just a few. Further, we do not have a complete results in the owner abandoning the process due to lack understanding of the inflammatory role of obesity of progress. Once you have set the appropriate weight hormones in our pets, and this could lead to an even loss target for that pet, then you can calculate the energy greater connection between obesity and disease. Finally, restriction that will be required to achieve the goals you as we have previously shown from the prospective study have set. Ideally, the best way to set the new energy of calorie-restricted dogs, dogs that are obese also do intake is to reduce intake to 60% to 80% of the pet’s not, on average, live as long as their leaner current intake. If the pets intake is not known (or cannot counterparts. The bottom line is that prevention of be calculated accurately), then it is necessary to obesity in dogs can increase both the quality and calculate an estimate of intake for the target weight. There are a number of different equations recommended for calculating maintenance energy requirements, and TREATMENT OF OBESITY: FROM DIET TO DRUGS
ones the most frequently used will be discussed. Finally, The management of obesity in dogs has long been another way that you can calculate calorie reduction is to focused on reducing energy consumption (dietary calculate the energy content of the amount of fat mass management) and increasing energy expenditure you wish the pet to lose (eg, 1 kg adipose tissue = 7700 (exercise). And, while this approach is very effective kcal) Take this number and divide by the number of when it is implemented completely, it can be quite days you plan to feed the weight reduction diet. That difficult to overcome the behavioral, social, metabolic, number is subtracted from the dog’s current intake to and hormonal influences of obesity and achieve long- achieve a new, lower number of calories for intake. This term success. In humans, obesity management options method is more cumbersome, but is based on a more include dietary management, exercise, behavior precise estimate of fat loss. Nevertheless, no matter modification, pharmacologic therapy, and surgery. At this which approach is used, the key to success is first to point, surgical therapy of obesity in dogs and cats is an have complete client cooperation, then to monitor the pet ethically gray area. Unfortunately, there have been no frequently (eg, every 3–4 weeks), and finally to make drugs licensed for weight loss in dogs or cats, and that adjustments in intake as needed based on the plan you has limited the potential therapeutic options for have developed. To be sure of accuracy in the weight veterinarians and pet owners. In this section, the dietary, loss period, it is important to weigh the pet on the same behavioral, physical and potential pharmacologic scale. To provide safe, but efficient weight loss, the dog approaches to obesity management will be discussed. should not lose more than 1–2% of its body an appetite suppressant, as lipase inhibition may result weight/week. in an increase in CCK (cholecystokinin) release resulting In addition to reducing the energy intake of pets that in satiety signaling. In contrast to orlistat, sibutramine is are overweight, it is also possible to increase weight loss a noradrenergic and serotoninergic re-uptake inhibitor by increasing energy expenditure through increased that enhances both satiety and thermogenesis (energy exercise. In obese dogs, as in obese humans, it is metabolism). This effect is identical to the effect important to start slow with an exercise program, and produced by fenfluramine (one of the drugs in the only very gradually and slowly increase the duration and previously available, now off the market, combo drug intensity of the exercise. In some dogs, exercise may be Fen-Phen (Phentermine) in that it reduces hunger and impossible, due to severe joint problems or exercise increases satiety. The most important potential risk from intolerance or due to inability of the owners to exercise the use of sibutramine is its sympathetic activity, as it with their pet. In these dogs, very minimal activity, or low has been shown to increase heart rate and blood impact activity, such as a treadmill or water treadmill pressure, which is very important in patients that have may be needed to allow safe, non-painful activity. preexisting heart or kidney disease, or hypertension. In Consultation with a veterinary physical rehabilitation addition to these two drugs, which have been used for specialist is often very helpful in determining appropriate weight loss, but have their limitations, a number of activities for the dog. This can also be part of the overall compounds are currently under investigation or are in diet and weight reduction plan, as the weigh-ins and clinical trials. One of these drugs is Rimonabant, an evaluation of the pet’s progress can occur in conjunction endocannabanoid CB1 receptor inverse agonist, that with the visits to the rehabilitation program. works by appetite suppression and reduction of food Many dogs become obese due to the social bonding intake. The drug is currently in multiple phase III clinical that occurs with owners and their dogs during feeding. trials and may become one of the newest members of This human–animal bond activity results in a strong the pharmacologic armamentarium. Topiramate, a newer behavioral component to the development of obesity that anticonvulsant drug, has also been shown to be an must be addressed. In order to achieve success in inhibitor of fat deposition and decreases intake. changing these behaviors, it is important to substitute However, at the doses required to induce weight loss, low calorie treats, games, or grooming activities for table significant side effects (psychomotor dysfunction) were scraps or other high calorie treats. Begging for food is observed. Currently the parent drug company is more of a behavioral problem than a hunger problem, reformulating the drug to attempt to develop a product and if this relationship is not considered in weight loss that may be both safe and effective for weight loss. At programs, the plan is doomed to fail. In some cases, this time, there are currently no drugs approved for use consultation with a veterinary behaviorist is an important in the United States for weight loss in dogs (although part of the overall plan for weight loss. there are several in the approval process), and only one recently approved drug in Europe. The mechanism of Other Therapeutic Options
action of the drug approved for weight loss in dogs is an In addition to traditional therapies used for weight MTP inhibitor whose mechanism of action is inhibiting regulation or weight loss, there is increasing interest in the digestion of fats. Thus, weight reduction occurs other modalities (drug therapy, surgical options, primarily by reducing energy uptake from the GI tract. nutraceuticals) that may improve the odds of success. Because of the difficulty in achieving weight loss in dogs, The surgical approach has become increasingly and the sheer number of obese dogs, it is likely that important in the management of the disease in humans, pharmacologic options for obesity management will but in veterinary medicine this approach carries become an increasingly important part of the overall considerable ethical gray areas and will not be approach to the problem. discussed in this forum. However, there are currently Nutraceutical therapy is also an increasingly three different pharmacological approaches to weight important aspect of therapy of weight loss. L-Carnitine, management currently available for use in humans: an amino acid synthesized from methionine and lysine in 1) drugs that reduce fat uptake from the intestine, the liver, has been used for several years to enhance fat 2) drugs that reduce appetite and 3) drugs that increase metabolism and help maintain lean muscle mass during metabolism (fat burning). Of these different types of weight loss. Incorporation of 100–300 ppm of L-Carnitine drugs, only two are currently approved for use in the US into diets has been shown to reduce lean muscle mass and they are orlistat (Xenical®) and sibutramine loss during weight loss lab animals, primarily due to (Meridia®, Reductil®). Orlistat is a derivative of a enhanced fatty acid oxidation and energy availability for lipostatin (isolated from a bacterium in the soil) that protein synthesis. To date there are no carefully inhibits gastrointestinal lipases. Thus, the mechanism of controlled studies in dogs that confirm the effectiveness action is that it blocks the breakdown of ingested dietary of carnitine in weight loss, but it is a reasonable and safe fat by preventing breakdown of triglycerides into nutraceutical therapy. Other nutraceutical alternatives monoglycerides and fatty acids that can be packaged that may enhance weight loss, but require additional into micelles and absorbed. The undigested fat is evaluation include conjugated linoleic acid (CLA) and excreted in feces, and thus the primary side effect of dietary diacylglycerol (DAG). The role of nutraceutical orlistat therapy is development of steatorrhea and therapy will likely continue to grow as approaches to diarrhea. In addition to these effects, orlistat may also be The North American Veterinary Conference – 2007 dietary therapy continue to be researched to seek new 6. Kealy RD, Lawler DF, Ballam JM, et al. Effects of diet restriction on life span and age related changes in dogs. J Am Vet Med Assoc 2002;220:1315-1320. Suggested Reading
7. Fascetti AJ. Obesity management in dogs and cats. 1. German AJ. The growing problem of obesity in dogs 8. Michel KE. Designing an effective weight reduction 2. Burkholder WJ. Precision and practicality of program. Proc Atlantic Coast Vet Conf, 2002. methods assessing body composition of dogs and 9. Umeda T, Bauer JE, Otsuji K. Weight loss effect of cats. Compend Contin Educ Pract Vet 2001;23:1-10. dietary diacylglycerol in obese dogs. J Anim Physiol 3. Mawby DI, Bartges JW, d Avignon A, et al. Comparison of various methods for estimating body 10. Halford JCG. Clinical Pharmacotherapy for obesity: fat in dogs. J Am Anim Hosp Assoc 2004;40:109- Current drugs and those in advanced development. 4. Trayhum P, Bing C, Wood, IS. Adipose tissue and 11. Macintosh MK. Nutrients and compounds affecting adipokines – Energy regulation from the human body composition and metabolism. Compend Contin perspective. J Nutr 2006;136:1935S-1939S. 5. Armstrong PJ, Lund EM, Kirk CA, et al. Prevalence 12. Yaissle JE, Holloway C, Buffington CAT. Evaluation and risk factors for obesity in dogs and cats. Proc of owner education as a component of obesity treatment programs for dogs. J Am Vet Med Assoc 2004;224:1932-1935.

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