Dietary Energy Restriction and Successful Weight Loss in Obese Client‐Owned Dogs

Dietary Energy Restriction and Successful Weight Loss in Obese Client‐Owned Dogs Background: Obesity is the most common nutritional disease in dogs. Although weight loss by dietary caloric energy restriction is successful in experimental studies, there is limited information on success of such programs in client-owned dogs who are obese. Further, no information currently exists on the changes in body composition during weight loss in clinical cases. Hypothesis: Key determinants of outcome of weight loss, including energy allocation and body composition, are influenced by both individual and weight program factors. Animals: Nineteen client-owned dogs with naturally occurring obesity. Methods: In this prospective clinical study, body composition was quantified by dual-energy X-ray absorptiometry before and after weight loss on an individually tailored program that incorporated a high-protein and moderate-fiber diet. Results: Mean percentage weight loss was 18% (range, 6–29%), and mean rate of weight loss was 0.85% per week (range, 0.35–1.56%). Mean energy allocation required to achieve weight loss was 60% of maintenance energy requirement at target weight (MERTW) (range, 50–82%). Significant dietary noncompliance was reported (mean, 1.0% MERTW; range, 0.0–9.5%). The mean composition of tissue lost was 84 : 15 : 1 (fat : lean : bone mineral content [BMC]). Lean tissue loss was positively associated with overall percentage of weight loss (Pearson correlation coefficient [Rp] 5 0.591, P 5 .008), whereas BMC loss was greater in retrievers compared with other breeds (1.9% 6 1.16% versus 0.8% 6 0.44%; P 5 .008). Conclusions and Clinical Importance: This clinical study demonstrated body composition changes during weight loss in dogs. Conventional programs produced safe weight loss, but marked energy restriction was required and the rate of loss was slower than in experimental studies. Key words: Canine; Dual-energy X-ray absorptiometry; Obesity. xcess weight and obesity are common in dogs, with a reported prevalence of between 22% and 40%.1,2 Given that overweight dogs are predisposed to a variety of associated diseases and have decreased longevity,1,3,4 correction of obesity is important. However, appropriate therapy may not be instigated, because obesity is often not noted as a diagnosis, perhaps reflecting the perception of practitioners that obesity or excessive weight does not constitute a disease state.4 Although pharmaceutical interventions will soon be available,5 obesity management currently involves a combination of dietary energy restriction and increasing physical activity. A number of studies examined the success of weight loss in dogs, especially those involving experimental trials.6–8 However, such data might not be fully representative of weight loss in a practice setting where the variables are less controlled than in a colony environment. Previous studies examined weight-loss regimes in client-owned dogs,9–12 but there is a need for more information on this topic. Ideally, adipose tissue alone is lost during weight loss, with preservation of lean tissue and bone mineral. Lean tissue loss in humans and cats is directly proportional to both the degree of caloric energy restriction and rate of weight loss.13–15 Diet composition is important in the relative amounts of the various body tissues that are lost by dogs.8 However, to date, all studies were experimental rather than clinical. The purpose of this study was to examine the mean energy allocation required for weight loss and the relative changes in body composition during weight loss in a cohort of client-owned dogs with naturally occurring obesity. The hypothesis was that both subject factors, including signalment, and weight program factors, including percentage of weight lost overall, rate of weight loss, etc, would influence body composition. We similarly hypothesized that subject factors could influence the energy allocation required for weight loss; however, given that weight program factors could both affect and be affected by the level of energy allocation during weight loss, we instead sought to determine associations between these variables. From the Department of Veterinary Clinical Sciences, Small Animal Teaching Hospital, University of Liverpool, Neston, Wirral, UK (German, Holden); The Royal Canin Research Center, Aimargues, France (Bissot, Biourge); and the The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, UK (Hackett). Reprint requests: A.J. German BVSc PhD CertSAM DipECVIM-CA MRCVS, Small Department of Veterinary Clinical Sciences, Animal Teaching Hospital, University of Liverpool, Chester High Road, Neston, Wirral CH64 7TE, UK; e-mail: ajgerman@liv.ac.uk. Submitted November 23, 2006; Revised February 13, 2007, March 28, 2007; Accepted May 18, 2007. Copyright E 2007 by the American College of Veterinary Internal Medicine 0891-6640/07/2106-0002/$3.00/0 Materials and Methods This was a prospective, uncontrolled, unmasked clinical trial. Dogs Nineteen dogs participated in this study. All were referred to the Royal Canin Weight Management Clinic (RCWMC), University of Liverpool, UK, for the investigation and management of obesity (n 5 7) or obesity-related disorders (n 5 12). For inclusion in the study, dogs had to be systemically healthy; euthyroid, as determined by measurement of free T4 by equilibrium dialysis; and have no clinically important abnormalities on CBC count, serum biochemical analysis, and urinalysis. Further, body composition data had to be available for each dog, from both before and after Weight Loss in Dogs Table 1. Composition of diets for weight loss. Criterion ME content Moisture Crude protein Crude fat Carbohydrate Crude fiber Total dietary fiber Ash L-carnitine Dried Rationa 3,275/kcal/kg AF 9.0% Per 100 g DM g/1000 kcal (ME) 37.1 10.9 21.0 12.2 21.6 8.6 218 113 33 64 37 66 26 66 Moist Rationb 3,670/kcal/kg DM 86.0% Per 100 g DM g/1000 kcal (ME) 55.0 12.1 7.1 2.9 10.0 15.7 20 159 35 21 8.3 29 42 5.8 ME, metabolizable energy; AF, as fed; DM, dry matter. Obesity Management (Dry), Royal Canin, Aimargues, France. b Obesity Management (Moist), Royal Canin, Aimargues, France. a period of weight loss. Dogs were enrolled between December 2004 and March 2006, and their period of weight loss was completed between May 2005 and September 2006. The study was performed in adherence to the University of Liverpool Animal Ethics Guidelines and was approved by the WALTHAM Ethical Review Committee. The owners of all participating dogs gave informed written consent. Evaluation before Weight Loss All dogs were weighed, body condition was scored,16 and body composition was assessed by dual-energy X-ray absorptiometry (DXA). Before weight loss, appropriate diagnostic investigations were performed for any obesity-associated or concurrent but unrelated disorder. Thereafter, an individually tailored weight management protocol was instigated (see below). Assessment of Weight and Body Composition Body weight was measured by electronic weigh scales (range, 0.05–100.00 kg)a, which were regularly validated for precision and accuracy by using test weights (2–50 kg; guaranteed accuracy #0.5%).b Body composition was analyzed by fan-beam DXA,c with high precision for repeat analysis in dogs.17 Dogs were either sedated (if DXA alone was performed) or anesthetized (if required for additional procedures, such as radiographic studies, surgery, routine dentistry), and scanned in dorsal recumbency, as previously described.17 Purpose-designed computer softwared was used for data analysis. energy allocation given was tailored to the individual patient, where sex and neuter status were factored in (eg, neutered female, entire female, neutered male, and entire males, 0.50, 0.55, 0.55, and 0.603 MER at the estimated target weight, respectively). Further adjustments were made, based upon other factors, eg, ability to exercise (greater restriction if concurrent orthopedic disease), current energy allocation (in cases referred after failure to lose weight at referring veterinary practice), sanctioned use of additional treats by the owner, and owners’ request for a gradual rather than sudden start to energy restriction. Dogs were fed either a dried or moist, high-protein, fat-restricted, moderate-fiber diet (Table 1). The choice of ration was tailored to the individual patient and depended upon previous dietary preferences. When the moist diet was used, the required amount was calculated and extrapolated to a proportion of the can or pouch; for the dried ration, the amount was extrapolated to weight in grams. For dried food, owners were asked to weigh food each day by using kitchen scales. To ensure accuracy, a 24-hour ration was first weighed on electronic scales (range, 1–5,000 g)e at the RCWMC, and then taken home by the client to weigh on their home scales. The RCWMC scales were regularly assessed for precision and reliability by using test weights (1–100 g; guaranteed accuracy #0.1%).d Lifestyle Alterations. At the time of the initial consultation, the owner was counseled on the lifestyle alterations that would be required to assist in weight loss. This, in part, covered education about the need to prevent excessive feeding, the need to avoid feeding extra food or treats, and information on strategies for providing nonfood-related rewards. Advice on increasing activity within the home environment was discussed for all dogs and included moving food bowls before meal times and encouraging the dog to follow, and a tailored exercise plan was devised for each dog. The type of exercise recommended included increasing play activity (n 5 19), lead walking exercise (n 5 17), and hydrotherapy (n 5 2). The exact recommendations for each dog took account of signalment, presence, and type of concurrent diseases, especially orthopedic disease, where applicable, and owner factors, including locality, occupation, lifestyle, personal circumstances. Monitoring. All dogs were assessed every 7–21 days, depending upon the availability of the owner during the weight-loss program. Body-weight measurements were taken and changes were made to the dietary plan if necessary. If an appointment was missed, then the owner would be contacted by telephone to discuss progress and to rearrange the appointment. The overall aim was to achieve 1–2% per week weight loss, although slower weight loss was acceptable if progress was steady. Throughout the weight-loss period, owners Weight-Loss Regimen Diet and Energy Allocation. Before weight loss, an initial target weight was set, based upon 2 calculations, one using starting body condition score and one using body composition determined by DXA. For the condition score method, it was assumed that each point on the 9-integer condition scoring system accounted for the dog being 10% above ideal weight.18 For the body composition method, the estimated fat mass was compared, with a reference range of 20–35% generated from dogs in ideal body condition; calculations aimed to return the dog to an upper reference range initially (30–35%), and assumed a predicted weight loss of 80 : 20 fat to nonfat mass. The results from each technique were compared, and the agreed initial target weight was set from a consensus of the 2 methods. For all calculations, the maintenance energy requirement (MER) equation used was MER 5 132 3 BW0.73,19 and MER was calculated by using the estimate of target weight. The initial German et al weight loss and the proportional change in body composition during weight loss. For energy allocation, the factors tested were signalment (age, breed, sex) and percentage of weight lost during the program; for body composition, the factors tested were signalment, energy allocation, rate of weight loss, percentage weight loss, and level of reported supplemental feeding. Given that the number of breeds represented was small, 2 breed groups were assessed: Labrador Retrievers and Golden Retrievers were assigned to the Retriever group, whereas all nonretriever breeds were assigned to the other breed group. The only other assessments made were comparisons of energy allocation and body composition (fat, lean, and bone mineral content [BMC]) at the start and end of weight of loss. All continuous data were first assessed for normal distribution (for the overall population and all subgroups) by using the Anderson-Darling method. Normality was confirmed for all data except BMC and energy contribution from supplemental feeding; however, BMC data became normally distributed after logarithmic transformation, whereas supplemental feeding data were normalized by square root transformation. Therefore, parametric statistical tests were used throughout; this included one-way analysis of variance for comparisons between sex, and 2-sample t-tests for breed group comparisons. Further, the Pearson correlation coefficient (Rp) was calculated to examine possible associations among continuous data sets, including the effects of age, percentage body weight, rate of weight loss, or level of supplemental feeding on the outcome variables, whereas paired ttests were used for the before and after weight loss comparisons for the outcome variables. Given that multiple statistical comparisons had been made, the level of significance was set at P , .01. maintained a diary that covered diet ration fed, activity, and any additional food that was consumed (either given as treats or stolen). At each reevaluation, changes were made to the weight-loss plan, as necessary. If progress was good, then no alteration in diet was made, but the owner was encouraged to step up activity wherever possible. If the dog had gained weight or was deemed to have lost insufficient weight, the potential causes were investigated, based upon the information provided by the owner in diary records and discussions during the consultation. If the cause was thought to be related to poor compliance to the diet, such as the administration of unsanctioned treats, the owner was encouraged to return to the diet plan and the amount of food fed was not changed. If activity levels had decreased, then the owner was encouraged to reinitiate these; however, where there was no obvious reason for poor progress, the amount fed was reduced by a readily calculated amount (eg, 5 g for a small dog or 10 g for a large dog on a dried ration; one fourth of a pouch for a small dog, one fourth of a 400-g can for a large dog on a moist ration) on each occasion. When weight loss was deemed to be too quick (.2% per week), the amount of diet was increased in similar increments. During the program, the body condition of the patient was continually assessed; the final target weight was altered if, as weight loss progressed, the initial estimate was not thought to be appropriate. Reevaluation at the End of Weight Loss. A detailed evaluation was conducted after the period of weight loss, the duration of which was variable. In 12 cases, dogs were evaluated when deemed to have reached their final target weight; in the remaining cases, reevaluation occurred before the final target weight was reached. In 7 cases target weight had not been achieved when a detailed re-evaluation was performed. In these cases, the re-evaluation was undertaken either on the request of the owner (eg, when an owner was convinced that optimal weight had been achieved prior to reaching the target set by the clinician, n 5 3), or because an additional procedure was required that needed the dog to be sedated or anesthetized (eg, radiography, surgery) (n 5 4). Dogs were confirmed to have remained healthy based upon physical examination, CBC count, serum biochemical analysis, and urinalysis. Body weight and body condition were recorded, and body composition was assessed by DXA. Other clinical procedures were performed, depending upon the requirements of the individual dogs and included radiography and surgery (cranial cruciate ligament surgery, n 5 3; elbow replacement, n 5 1). Estimation of Supplementary Energy Intake from Additional Fed Items. The diary information recorded by the owners included a description of additional foodstuffs that the dog had consumed. The caloric value of all items was estimated either from the known energy densities of food (derived from packaging information) or from published information on caloric content of food.20,21 Statistical Analysis. All data were expressed as mean and standard deviation or as median and range. The equation for MER used in the weight-loss calculations for the current study (MER 5 132 3 BW0.73) was based upon the 1974 NRC recommendations.18 However, new recommendations on MER for pet dogs became available after the study commenced.22 Therefore, to ensure that the results of the study were relevant to the current state of the science, results for energy allocation data were expressed as percentage of MER at target body weight (TBW), where MER 5 105 3 BW0.75.22 The final TBW was used in dogs who completed weight loss; for dogs who underwent detailed reevaluation before reaching optimal body weight, the estimated TBW was used. Statistical analysis was performed with a computer software package.f Several factors were examined for their effect on 2 key outcome measures, the mean level of energy allocation required for Results Study Animals Labrador Retrievers (n 5 7) were the most common breed in the study population, whereas other represented breeds included mixed breed (n 5 4), Golden Retriever (n 5 2), Yorkshire Terrier (n 5 2), Bernese Mountain Dog (n 5 1), Cocker Spaniel (n 5 1), Lhasa Apso (n 5 1), and Newfoundland (n 5 1). The median age was 78 months (range, 38–166 months). Thirteen dogs were male (10 neutered); 5 of the 6 female dogs were neutered, whereas the final dog was initially entire but was neutered during weight loss for medical reasons (ie, to assist with seizure control). One dog had recently suffered from acute pancreatitis, and weight loss was delayed until the patient was clinically stable. Other associated diseases included orthopedic disease (cranial cruciate ligament disease, n 5 3; osteoarthritis, n 5 2; undetermined lameness, n 5 1), urinary tract disease (ectopic ureter, n 5 1; urethral sphincter mechanism incompetence, n 5 1), and cardiorespiratory disease (tracheal collapse, n 5 1; idiopathic pulmonary hypertension, n 5 1). For these cases, weight management formed an integral part of treatment. Summary of Weight Loss The median duration of weight loss was 144 days (range, 84–427 days), weight lost was 18% 6 6.2%, and the rate of weight loss for all dogs was 0.85% 6 0.344% per week (Table 2). The median number of examinations (including initial and final examination) was 9 (range, 5– 18), and the median time between revisits was 15 days (range, 5–71 days). Five dogs did not require any change Weight Loss in Dogs Table 2. Weight loss in 19 dogs on a weight-loss program. Weight-Loss Characteristic Body weight (kg) Start End Final targetb Duration of weight loss (days) Percentage weight loss Body condition score Before After Diet energy allocation (kcal)c Start End Mean Energy from extras (kcal)c,d Rate of weight losse Result Table 3. Body composition of 19 dogs undergoing weight loss. Mean Standard Deviation 11,910 9,293 616.1 7,961 8,989 582.8 4,127 1,250 53.0 14.7 15.4 1.0 38.4 6 22.90 31.4 6 17.65 29.8 6 15.37 177 6 98.2 18.9 6 6.18 7 (6–9) 5 (5–6) 64 58 60 1.0 0.85 6 9.4 6 9.7 6 8.1 (0.0–9.5) 6 0.344 Before (g) Fat Lean BMC1 After (g) Fat Lean BMC Change (total) (g) Fat Lean BMC Percentage change Fat Lean BMC BMC, bone mineral content. 83 15 1 5,470 1,080 74 10,600 16,700 970 16,100 17,700 1,040 Results presented as mean 6 standard deviation for body weight, duration of weight loss, percentage weight loss, diet energy allocation, and rate of weight loss. Results are presented as median (range) for body condition score and energy from extras. b Final target refers either to final weight, in dogs in ideal body weight after the diet, or predicted target if weight loss was not completed. c Expressed as a percentage of metabolizable energy requirement at final target body weight (MER 5 105 3 W0.75). d Extras are nonsanctioned treats and food scavenged by the dog. e Expressed in percentage of starting body weight loss per week. to the amount of food fed during the period of weight loss. Of the 14 dogs where amendments were made, the amount fed was increased on at least one occasion in 5 dogs (once, n 5 3; twice, n 5 1; 3 times, n 5 1) and decreased on at least one occasion in all 14 dogs (median, 1 changes; range, 1–9). The median amount by which the diet was increased was 3% (range, 2–10%); the median amount by which the diet was decreased was 4% (range, 2–14%). requests to do so; this dog lost least weight during the study. Noncompliance consisted of the owner treating the dog (16/17) and by the dog stealing food (12/17). A wide range of additional foodstuffs were eaten, including canine foods and snacks (eg, obesity diet ration, standard maintenance diets, dog biscuits, pigs’ ears, chocolate drops), human foods (eg, bread, dairy produce [butter, milk cheese], potato chips, French fries, chocolate, various types of candy and confectionary, pasta, various cooked meats and fish, fruit and vegetables, breakfast cereal, beer, and deserts), and other animal species foods (eg, bird seed, cat food). The median estimated contribution to dietary caloric intake from noncompliance was 1.0% MER at TBW (range, 0.0–9.5%). Body Composition Energy Allocation Required for Weight Loss The mean level of dietary caloric energy allocation (for the whole weight-loss period) was 60% of MER TBW (median, 60% of MER TBW; range, 50–82%). The energy allocation required to ensure that weight loss continued during the program (mean 6 SD for allocation at the start versus the end at of weight loss; 64% 6 9.4% versus 58% 6 9.7%, P 5 .004). Although apparent differences between sexes were noted, these were not significant (mean 6SD for entire male 70% 6 8.9% versus neutered male 57% 6 6.0% versus neutered female 58 6 6.3%; one-way ANOVA; P 5 .019). No other factor (eg, breed, age, percentage body weight lost) had any significant effect on the degree of caloric restriction required for weight loss. Significant decreases were noted for fat, lean, and BMC (P , .001 for all), when compared before and after weight loss (Table 3, Fig 1). Loss of lean mass was positively associated with the percentage of body weight lost (Rp 5 0.591, P 5 .008). No other factor (eg, signalment, mean energy allocation during weight loss, rate of weight loss, or level of reported supplemental feeding) had any significant effect on the amount of lean tissue lost. Dogs of the retriever group lost proportionally more BMC during weight loss than dogs of other breeds (mean for retriever group 1.9% 6 1.16% versus 0.8% 6 0.44% for other breeds; P 5 .008). No other factor (eg, sex, age, level of energy allocation during weight loss, rate of weight loss, or level of reported supplemental feeding) had any significant effect on the amount of BMC lost. Dietary Noncompliance Owners reported dietary noncompliance in 17 of 19 cases (Table 2). In a further 1 dog, frequent noncompliance was admitted but no record was maintained, despite Discussion This study showed that conventional weight management therapy could be successful in naturally occurring German et al Fig 1. Mean change in body composition during weight loss, assessed by dual-energy X-ray absorptiometry, in 19 overweight dogs before and after weight management. Although significant decreases in all components (lean mass, bone mineral content [BMC], and fat mass) were noted, the predominant loss was in fat mass (median, 83%). obesity in client-owned dogs. The mean rate of weight loss achieved (0.84% per week) was slower than observed in studies with diets of similar composition in colony dogs where rates of weight loss of 1.3–2.6% per week were achieved.6–8 However, the results concur with the findings of previous clinical studies9–12 and suggest clinicians should expect slower rates of weight lost in client-owned dogs in the clinical setting. Although these data provide useful information on current weight-loss strategies for dogs, there may be problems in extrapolating directly the results to practitioners in first-opinion practice. In this respect, a referral population was studied, and some dogs had been referred because weight loss had been unsuccessful at the practice of the referring veterinarian. Further, in the weight management clinic, a full-time member of staff (SH) is employed specifically to oversee weight-loss programs, enabling more intensive supervision than is possible in many firstopinion practices. This may, to an extent, counteract the problems faced by the population of dogs referred. Thus, the results of the current study may not be completely representative of what may be expected in general practice. There are many possible reasons for why weight loss in client-owned dogs may be slower than in colony dogs, including differences in signalment, exercise levels, ambient temperature, concurrent illness, and issues of compliance with the dietary regime. Previous work with colony dogs demonstrated breed differences in the level of energy restriction required to achieve the same rate of weight loss, with Labradors requiring a greater level of restriction than Beagles.g Age, sex, neuter status, and activity level also were shown to be of importance. Indeed, the latest National Research Council guidelines on nutrient requirements for dogs suggested that energy requirements differ among groups.22 Active colony dogs have a higher daily MER (130 kcal/kg BW0.75) than older or inactive pet dogs (95–105 kcal/kg BW0.75), whereas the requirements for young colony dogs may be higher still (140–220 kcal/kg BW0.75).22 It is noteworthy that the range in energy allocation required for satisfactory weight loss in the current study (50–82% MER at TBW) was similar to that reported in previous colony studies when using a similar diet (50–87% MER at TBW).6–8 However, it should be emphasized that the total number of calories actually consumed by dogs in the current study is lower because the MER for pet dogs was used (105 kcal/kg BW0.75). If the maintenance energy equation from the colony studies (132 kcal/kg BW0.73) had been used, then the equivalent range of energy allocations for dogs of the current study would have been 42–70% MER at TBW. This suggests that not only is the rate of weight loss slower for client-owned dogs on a weight-loss program but that energy must be restricted to a greater degree. One notable conclusion of the current study was the wide variability of energy allocation requirements to achieve satisfactory weight loss among dogs (50–82% MER TBW). The reasons for such a discrepancy are unclear but may be attributed to different environmental factors and demographics. This highlights the importance of tailoring the program to the individual and being prepared to make changes if the weight loss does not progress satisfactorily. This issue is highlighted by the fact that 14 of 19 dogs of the current studies required at least one alteration in their weight-loss program. We estimated the degree of dietary noncompliance in each dog from diary records maintained by the owner, and results suggested marked variability in its contribution to overall daily intake. Although overall energy consumption from this source was minor in many cases (eg, ,1% MER TBW in 9/19 dogs), reported supplemental feeding was a particular concern in some dogs, resulting in .3% MER TBW in 4 dogs. However, the true caloric contribution from noncompliance may actually be greater, given the suspected underreporting from owners, and this was an acknowledged limitation of human studies that use such an approach.23 Such a possibility was highlighted by the least successful dog in the current program, where the owner admitted noncompliance yet no record was maintained. A further limitation was the method of estimating the caloric intake from extras, which was with reference to human ‘‘calorie counter’’ guides and information supplied by pet food companies. Imprecision in the figures was possible, given that listed figures were based on an average portion size and owners were not always precise about the exact amounts of food consumed. Nevertheless, the 3 dogs with the greatest reported energy contributions from extras, all successfully achieved their TBWs. This is probably because knowledge of the supplemental feeding enabled us to rectify the problem by advising the owners to reduce the noncompliance in subsequent weeks or by reducing the amount of diet Weight Loss in Dogs food fed. Thus, to ensure predictable weight loss, clinicians should strive to prevent such unwanted calories as much as possible. However, because giving treats is an important part of pet ownership, it can be sanctioned, as long as the clinician maintains a record so that it can be factored into the total daily allowance for the dog. In the current study, sex differences were suggested, with entire male dogs needing less marked restriction, although these were not significant at the P , .01 level. However, it is possible that the small study numbers resulted in insufficient statistical power and that the true effect was missed. This supposition is supported by the findings of previous work that demonstrated similar sex influences on the degree of energy restriction for successful weight loss.24 Thus, the current practice of commencing weight-loss regimes at different energy allocation levels dependent upon sex and neuter status is appropriate. Other than sex, there were no other strong predictors of either the rate of weight loss or the level of energy allocation required; hence, with clientowned dogs, clinicians must monitor the program closely and make alterations whenever required. In keeping with the results of experimental studies that used a diet of similar composition, the majority (.80%) of tissue mass lost by dogs in this study was adipose tissue, with smaller, although significant, losses of lean tissue and BMC. In the current study, the main factor associated with the amount of lean tissue lost was the overall percentage weight loss in that dogs who lost a greater proportion of body weight lost more lean tissue. In contrast to work in cats and humans,13–15 the rate of weight loss and the degree of caloric restriction did not have a significant impact on the proportion of lean and fat lost. The reasons for this discrepancy were not clear but could relate to the relatively slower rate of weight loss for dogs in this study compared with the work in other species. Incorporating exercise in weightloss programs has been shown to assist in lean tissue preservation during weight loss in human patients.25,26 However, this factor was not examined during the current study. In summary, the current study demonstrated that successful weight loss in obese dogs was feasible in clinical practice by using a conventional approach with dietary caloric energy restriction and increased activity. However, marked caloric energy restriction is required, and the rate of weight loss is slower than in equivalent experimental studies. The main predictor of the amount of lean tissue lost was the overall percentage weight loss, suggesting that this may be inevitable in animals required to lose a large proportion of their body mass. e f Salter, Tonbridge, UK Minitab v14.0; Minitab Inc, Quality Plaza, State College, PA g Bissot T, Servet E, Biourge V. Energy allowance to induce weight loss is affected by breed and sex but not diet. Proceedings of the 10th Congress of the European Society of Veterinary and Comparative Nutrition, Nantes, France 2006:188 (abstract) Acknowledgments The authors thank the referring veterinarians for referring cases, and the clinical staff at the University of Liverpool for assistance with case management. Eric Servet, Renaud Sergheraert, and John Rawlings are acknowledged for their assistance. AG’s senior lectureship is funded by Royal Canin. This study was funded by a grant from WALTHAM. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Veterinary Internal Medicine Wiley

Dietary Energy Restriction and Successful Weight Loss in Obese Client‐Owned Dogs

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Abstract

Background: Obesity is the most common nutritional disease in dogs. Although weight loss by dietary caloric energy restriction is successful in experimental studies, there is limited information on success of such programs in client-owned dogs who are obese. Further, no information currently exists on the changes in body composition during weight loss in clinical cases. Hypothesis: Key determinants of outcome of weight loss, including energy allocation and body composition, are influenced by both individual and weight program factors. Animals: Nineteen client-owned dogs with naturally occurring obesity. Methods: In this prospective clinical study, body composition was quantified by dual-energy X-ray absorptiometry before and after weight loss on an individually tailored program that incorporated a high-protein and moderate-fiber diet. Results: Mean percentage weight loss was 18% (range, 6–29%), and mean rate of weight loss was 0.85% per week (range, 0.35–1.56%). Mean energy allocation required to achieve weight loss was 60% of maintenance energy requirement at target weight (MERTW) (range, 50–82%). Significant dietary noncompliance was reported (mean, 1.0% MERTW; range, 0.0–9.5%). The mean composition of tissue lost was 84 : 15 : 1 (fat : lean : bone mineral content [BMC]). Lean tissue loss was positively associated with overall percentage of weight loss (Pearson correlation coefficient [Rp] 5 0.591, P 5 .008), whereas BMC loss was greater in retrievers compared with other breeds (1.9% 6 1.16% versus 0.8% 6 0.44%; P 5 .008). Conclusions and Clinical Importance: This clinical study demonstrated body composition changes during weight loss in dogs. Conventional programs produced safe weight loss, but marked energy restriction was required and the rate of loss was slower than in experimental studies. Key words: Canine; Dual-energy X-ray absorptiometry; Obesity. xcess weight and obesity are common in dogs, with a reported prevalence of between 22% and 40%.1,2 Given that overweight dogs are predisposed to a variety of associated diseases and have decreased longevity,1,3,4 correction of obesity is important. However, appropriate therapy may not be instigated, because obesity is often not noted as a diagnosis, perhaps reflecting the perception of practitioners that obesity or excessive weight does not constitute a disease state.4 Although pharmaceutical interventions will soon be available,5 obesity management currently involves a combination of dietary energy restriction and increasing physical activity. A number of studies examined the success of weight loss in dogs, especially those involving experimental trials.6–8 However, such data might not be fully representative of weight loss in a practice setting where the variables are less controlled than in a colony environment. Previous studies examined weight-loss regimes in client-owned dogs,9–12 but there is a need for more information on this topic. Ideally, adipose tissue alone is lost during weight loss, with preservation of lean tissue and bone mineral. Lean tissue loss in humans and cats is directly proportional to both the degree of caloric energy restriction and rate of weight loss.13–15 Diet composition is important in the relative amounts of the various body tissues that are lost by dogs.8 However, to date, all studies were experimental rather than clinical. The purpose of this study was to examine the mean energy allocation required for weight loss and the relative changes in body composition during weight loss in a cohort of client-owned dogs with naturally occurring obesity. The hypothesis was that both subject factors, including signalment, and weight program factors, including percentage of weight lost overall, rate of weight loss, etc, would influence body composition. We similarly hypothesized that subject factors could influence the energy allocation required for weight loss; however, given that weight program factors could both affect and be affected by the level of energy allocation during weight loss, we instead sought to determine associations between these variables. From the Department of Veterinary Clinical Sciences, Small Animal Teaching Hospital, University of Liverpool, Neston, Wirral, UK (German, Holden); The Royal Canin Research Center, Aimargues, France (Bissot, Biourge); and the The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, UK (Hackett). Reprint requests: A.J. German BVSc PhD CertSAM DipECVIM-CA MRCVS, Small Department of Veterinary Clinical Sciences, Animal Teaching Hospital, University of Liverpool, Chester High Road, Neston, Wirral CH64 7TE, UK; e-mail: ajgerman@liv.ac.uk. Submitted November 23, 2006; Revised February 13, 2007, March 28, 2007; Accepted May 18, 2007. Copyright E 2007 by the American College of Veterinary Internal Medicine 0891-6640/07/2106-0002/$3.00/0 Materials and Methods This was a prospective, uncontrolled, unmasked clinical trial. Dogs Nineteen dogs participated in this study. All were referred to the Royal Canin Weight Management Clinic (RCWMC), University of Liverpool, UK, for the investigation and management of obesity (n 5 7) or obesity-related disorders (n 5 12). For inclusion in the study, dogs had to be systemically healthy; euthyroid, as determined by measurement of free T4 by equilibrium dialysis; and have no clinically important abnormalities on CBC count, serum biochemical analysis, and urinalysis. Further, body composition data had to be available for each dog, from both before and after Weight Loss in Dogs Table 1. Composition of diets for weight loss. Criterion ME content Moisture Crude protein Crude fat Carbohydrate Crude fiber Total dietary fiber Ash L-carnitine Dried Rationa 3,275/kcal/kg AF 9.0% Per 100 g DM g/1000 kcal (ME) 37.1 10.9 21.0 12.2 21.6 8.6 218 113 33 64 37 66 26 66 Moist Rationb 3,670/kcal/kg DM 86.0% Per 100 g DM g/1000 kcal (ME) 55.0 12.1 7.1 2.9 10.0 15.7 20 159 35 21 8.3 29 42 5.8 ME, metabolizable energy; AF, as fed; DM, dry matter. Obesity Management (Dry), Royal Canin, Aimargues, France. b Obesity Management (Moist), Royal Canin, Aimargues, France. a period of weight loss. Dogs were enrolled between December 2004 and March 2006, and their period of weight loss was completed between May 2005 and September 2006. The study was performed in adherence to the University of Liverpool Animal Ethics Guidelines and was approved by the WALTHAM Ethical Review Committee. The owners of all participating dogs gave informed written consent. Evaluation before Weight Loss All dogs were weighed, body condition was scored,16 and body composition was assessed by dual-energy X-ray absorptiometry (DXA). Before weight loss, appropriate diagnostic investigations were performed for any obesity-associated or concurrent but unrelated disorder. Thereafter, an individually tailored weight management protocol was instigated (see below). Assessment of Weight and Body Composition Body weight was measured by electronic weigh scales (range, 0.05–100.00 kg)a, which were regularly validated for precision and accuracy by using test weights (2–50 kg; guaranteed accuracy #0.5%).b Body composition was analyzed by fan-beam DXA,c with high precision for repeat analysis in dogs.17 Dogs were either sedated (if DXA alone was performed) or anesthetized (if required for additional procedures, such as radiographic studies, surgery, routine dentistry), and scanned in dorsal recumbency, as previously described.17 Purpose-designed computer softwared was used for data analysis. energy allocation given was tailored to the individual patient, where sex and neuter status were factored in (eg, neutered female, entire female, neutered male, and entire males, 0.50, 0.55, 0.55, and 0.603 MER at the estimated target weight, respectively). Further adjustments were made, based upon other factors, eg, ability to exercise (greater restriction if concurrent orthopedic disease), current energy allocation (in cases referred after failure to lose weight at referring veterinary practice), sanctioned use of additional treats by the owner, and owners’ request for a gradual rather than sudden start to energy restriction. Dogs were fed either a dried or moist, high-protein, fat-restricted, moderate-fiber diet (Table 1). The choice of ration was tailored to the individual patient and depended upon previous dietary preferences. When the moist diet was used, the required amount was calculated and extrapolated to a proportion of the can or pouch; for the dried ration, the amount was extrapolated to weight in grams. For dried food, owners were asked to weigh food each day by using kitchen scales. To ensure accuracy, a 24-hour ration was first weighed on electronic scales (range, 1–5,000 g)e at the RCWMC, and then taken home by the client to weigh on their home scales. The RCWMC scales were regularly assessed for precision and reliability by using test weights (1–100 g; guaranteed accuracy #0.1%).d Lifestyle Alterations. At the time of the initial consultation, the owner was counseled on the lifestyle alterations that would be required to assist in weight loss. This, in part, covered education about the need to prevent excessive feeding, the need to avoid feeding extra food or treats, and information on strategies for providing nonfood-related rewards. Advice on increasing activity within the home environment was discussed for all dogs and included moving food bowls before meal times and encouraging the dog to follow, and a tailored exercise plan was devised for each dog. The type of exercise recommended included increasing play activity (n 5 19), lead walking exercise (n 5 17), and hydrotherapy (n 5 2). The exact recommendations for each dog took account of signalment, presence, and type of concurrent diseases, especially orthopedic disease, where applicable, and owner factors, including locality, occupation, lifestyle, personal circumstances. Monitoring. All dogs were assessed every 7–21 days, depending upon the availability of the owner during the weight-loss program. Body-weight measurements were taken and changes were made to the dietary plan if necessary. If an appointment was missed, then the owner would be contacted by telephone to discuss progress and to rearrange the appointment. The overall aim was to achieve 1–2% per week weight loss, although slower weight loss was acceptable if progress was steady. Throughout the weight-loss period, owners Weight-Loss Regimen Diet and Energy Allocation. Before weight loss, an initial target weight was set, based upon 2 calculations, one using starting body condition score and one using body composition determined by DXA. For the condition score method, it was assumed that each point on the 9-integer condition scoring system accounted for the dog being 10% above ideal weight.18 For the body composition method, the estimated fat mass was compared, with a reference range of 20–35% generated from dogs in ideal body condition; calculations aimed to return the dog to an upper reference range initially (30–35%), and assumed a predicted weight loss of 80 : 20 fat to nonfat mass. The results from each technique were compared, and the agreed initial target weight was set from a consensus of the 2 methods. For all calculations, the maintenance energy requirement (MER) equation used was MER 5 132 3 BW0.73,19 and MER was calculated by using the estimate of target weight. The initial German et al weight loss and the proportional change in body composition during weight loss. For energy allocation, the factors tested were signalment (age, breed, sex) and percentage of weight lost during the program; for body composition, the factors tested were signalment, energy allocation, rate of weight loss, percentage weight loss, and level of reported supplemental feeding. Given that the number of breeds represented was small, 2 breed groups were assessed: Labrador Retrievers and Golden Retrievers were assigned to the Retriever group, whereas all nonretriever breeds were assigned to the other breed group. The only other assessments made were comparisons of energy allocation and body composition (fat, lean, and bone mineral content [BMC]) at the start and end of weight of loss. All continuous data were first assessed for normal distribution (for the overall population and all subgroups) by using the Anderson-Darling method. Normality was confirmed for all data except BMC and energy contribution from supplemental feeding; however, BMC data became normally distributed after logarithmic transformation, whereas supplemental feeding data were normalized by square root transformation. Therefore, parametric statistical tests were used throughout; this included one-way analysis of variance for comparisons between sex, and 2-sample t-tests for breed group comparisons. Further, the Pearson correlation coefficient (Rp) was calculated to examine possible associations among continuous data sets, including the effects of age, percentage body weight, rate of weight loss, or level of supplemental feeding on the outcome variables, whereas paired ttests were used for the before and after weight loss comparisons for the outcome variables. Given that multiple statistical comparisons had been made, the level of significance was set at P , .01. maintained a diary that covered diet ration fed, activity, and any additional food that was consumed (either given as treats or stolen). At each reevaluation, changes were made to the weight-loss plan, as necessary. If progress was good, then no alteration in diet was made, but the owner was encouraged to step up activity wherever possible. If the dog had gained weight or was deemed to have lost insufficient weight, the potential causes were investigated, based upon the information provided by the owner in diary records and discussions during the consultation. If the cause was thought to be related to poor compliance to the diet, such as the administration of unsanctioned treats, the owner was encouraged to return to the diet plan and the amount of food fed was not changed. If activity levels had decreased, then the owner was encouraged to reinitiate these; however, where there was no obvious reason for poor progress, the amount fed was reduced by a readily calculated amount (eg, 5 g for a small dog or 10 g for a large dog on a dried ration; one fourth of a pouch for a small dog, one fourth of a 400-g can for a large dog on a moist ration) on each occasion. When weight loss was deemed to be too quick (.2% per week), the amount of diet was increased in similar increments. During the program, the body condition of the patient was continually assessed; the final target weight was altered if, as weight loss progressed, the initial estimate was not thought to be appropriate. Reevaluation at the End of Weight Loss. A detailed evaluation was conducted after the period of weight loss, the duration of which was variable. In 12 cases, dogs were evaluated when deemed to have reached their final target weight; in the remaining cases, reevaluation occurred before the final target weight was reached. In 7 cases target weight had not been achieved when a detailed re-evaluation was performed. In these cases, the re-evaluation was undertaken either on the request of the owner (eg, when an owner was convinced that optimal weight had been achieved prior to reaching the target set by the clinician, n 5 3), or because an additional procedure was required that needed the dog to be sedated or anesthetized (eg, radiography, surgery) (n 5 4). Dogs were confirmed to have remained healthy based upon physical examination, CBC count, serum biochemical analysis, and urinalysis. Body weight and body condition were recorded, and body composition was assessed by DXA. Other clinical procedures were performed, depending upon the requirements of the individual dogs and included radiography and surgery (cranial cruciate ligament surgery, n 5 3; elbow replacement, n 5 1). Estimation of Supplementary Energy Intake from Additional Fed Items. The diary information recorded by the owners included a description of additional foodstuffs that the dog had consumed. The caloric value of all items was estimated either from the known energy densities of food (derived from packaging information) or from published information on caloric content of food.20,21 Statistical Analysis. All data were expressed as mean and standard deviation or as median and range. The equation for MER used in the weight-loss calculations for the current study (MER 5 132 3 BW0.73) was based upon the 1974 NRC recommendations.18 However, new recommendations on MER for pet dogs became available after the study commenced.22 Therefore, to ensure that the results of the study were relevant to the current state of the science, results for energy allocation data were expressed as percentage of MER at target body weight (TBW), where MER 5 105 3 BW0.75.22 The final TBW was used in dogs who completed weight loss; for dogs who underwent detailed reevaluation before reaching optimal body weight, the estimated TBW was used. Statistical analysis was performed with a computer software package.f Several factors were examined for their effect on 2 key outcome measures, the mean level of energy allocation required for Results Study Animals Labrador Retrievers (n 5 7) were the most common breed in the study population, whereas other represented breeds included mixed breed (n 5 4), Golden Retriever (n 5 2), Yorkshire Terrier (n 5 2), Bernese Mountain Dog (n 5 1), Cocker Spaniel (n 5 1), Lhasa Apso (n 5 1), and Newfoundland (n 5 1). The median age was 78 months (range, 38–166 months). Thirteen dogs were male (10 neutered); 5 of the 6 female dogs were neutered, whereas the final dog was initially entire but was neutered during weight loss for medical reasons (ie, to assist with seizure control). One dog had recently suffered from acute pancreatitis, and weight loss was delayed until the patient was clinically stable. Other associated diseases included orthopedic disease (cranial cruciate ligament disease, n 5 3; osteoarthritis, n 5 2; undetermined lameness, n 5 1), urinary tract disease (ectopic ureter, n 5 1; urethral sphincter mechanism incompetence, n 5 1), and cardiorespiratory disease (tracheal collapse, n 5 1; idiopathic pulmonary hypertension, n 5 1). For these cases, weight management formed an integral part of treatment. Summary of Weight Loss The median duration of weight loss was 144 days (range, 84–427 days), weight lost was 18% 6 6.2%, and the rate of weight loss for all dogs was 0.85% 6 0.344% per week (Table 2). The median number of examinations (including initial and final examination) was 9 (range, 5– 18), and the median time between revisits was 15 days (range, 5–71 days). Five dogs did not require any change Weight Loss in Dogs Table 2. Weight loss in 19 dogs on a weight-loss program. Weight-Loss Characteristic Body weight (kg) Start End Final targetb Duration of weight loss (days) Percentage weight loss Body condition score Before After Diet energy allocation (kcal)c Start End Mean Energy from extras (kcal)c,d Rate of weight losse Result Table 3. Body composition of 19 dogs undergoing weight loss. Mean Standard Deviation 11,910 9,293 616.1 7,961 8,989 582.8 4,127 1,250 53.0 14.7 15.4 1.0 38.4 6 22.90 31.4 6 17.65 29.8 6 15.37 177 6 98.2 18.9 6 6.18 7 (6–9) 5 (5–6) 64 58 60 1.0 0.85 6 9.4 6 9.7 6 8.1 (0.0–9.5) 6 0.344 Before (g) Fat Lean BMC1 After (g) Fat Lean BMC Change (total) (g) Fat Lean BMC Percentage change Fat Lean BMC BMC, bone mineral content. 83 15 1 5,470 1,080 74 10,600 16,700 970 16,100 17,700 1,040 Results presented as mean 6 standard deviation for body weight, duration of weight loss, percentage weight loss, diet energy allocation, and rate of weight loss. Results are presented as median (range) for body condition score and energy from extras. b Final target refers either to final weight, in dogs in ideal body weight after the diet, or predicted target if weight loss was not completed. c Expressed as a percentage of metabolizable energy requirement at final target body weight (MER 5 105 3 W0.75). d Extras are nonsanctioned treats and food scavenged by the dog. e Expressed in percentage of starting body weight loss per week. to the amount of food fed during the period of weight loss. Of the 14 dogs where amendments were made, the amount fed was increased on at least one occasion in 5 dogs (once, n 5 3; twice, n 5 1; 3 times, n 5 1) and decreased on at least one occasion in all 14 dogs (median, 1 changes; range, 1–9). The median amount by which the diet was increased was 3% (range, 2–10%); the median amount by which the diet was decreased was 4% (range, 2–14%). requests to do so; this dog lost least weight during the study. Noncompliance consisted of the owner treating the dog (16/17) and by the dog stealing food (12/17). A wide range of additional foodstuffs were eaten, including canine foods and snacks (eg, obesity diet ration, standard maintenance diets, dog biscuits, pigs’ ears, chocolate drops), human foods (eg, bread, dairy produce [butter, milk cheese], potato chips, French fries, chocolate, various types of candy and confectionary, pasta, various cooked meats and fish, fruit and vegetables, breakfast cereal, beer, and deserts), and other animal species foods (eg, bird seed, cat food). The median estimated contribution to dietary caloric intake from noncompliance was 1.0% MER at TBW (range, 0.0–9.5%). Body Composition Energy Allocation Required for Weight Loss The mean level of dietary caloric energy allocation (for the whole weight-loss period) was 60% of MER TBW (median, 60% of MER TBW; range, 50–82%). The energy allocation required to ensure that weight loss continued during the program (mean 6 SD for allocation at the start versus the end at of weight loss; 64% 6 9.4% versus 58% 6 9.7%, P 5 .004). Although apparent differences between sexes were noted, these were not significant (mean 6SD for entire male 70% 6 8.9% versus neutered male 57% 6 6.0% versus neutered female 58 6 6.3%; one-way ANOVA; P 5 .019). No other factor (eg, breed, age, percentage body weight lost) had any significant effect on the degree of caloric restriction required for weight loss. Significant decreases were noted for fat, lean, and BMC (P , .001 for all), when compared before and after weight loss (Table 3, Fig 1). Loss of lean mass was positively associated with the percentage of body weight lost (Rp 5 0.591, P 5 .008). No other factor (eg, signalment, mean energy allocation during weight loss, rate of weight loss, or level of reported supplemental feeding) had any significant effect on the amount of lean tissue lost. Dogs of the retriever group lost proportionally more BMC during weight loss than dogs of other breeds (mean for retriever group 1.9% 6 1.16% versus 0.8% 6 0.44% for other breeds; P 5 .008). No other factor (eg, sex, age, level of energy allocation during weight loss, rate of weight loss, or level of reported supplemental feeding) had any significant effect on the amount of BMC lost. Dietary Noncompliance Owners reported dietary noncompliance in 17 of 19 cases (Table 2). In a further 1 dog, frequent noncompliance was admitted but no record was maintained, despite Discussion This study showed that conventional weight management therapy could be successful in naturally occurring German et al Fig 1. Mean change in body composition during weight loss, assessed by dual-energy X-ray absorptiometry, in 19 overweight dogs before and after weight management. Although significant decreases in all components (lean mass, bone mineral content [BMC], and fat mass) were noted, the predominant loss was in fat mass (median, 83%). obesity in client-owned dogs. The mean rate of weight loss achieved (0.84% per week) was slower than observed in studies with diets of similar composition in colony dogs where rates of weight loss of 1.3–2.6% per week were achieved.6–8 However, the results concur with the findings of previous clinical studies9–12 and suggest clinicians should expect slower rates of weight lost in client-owned dogs in the clinical setting. Although these data provide useful information on current weight-loss strategies for dogs, there may be problems in extrapolating directly the results to practitioners in first-opinion practice. In this respect, a referral population was studied, and some dogs had been referred because weight loss had been unsuccessful at the practice of the referring veterinarian. Further, in the weight management clinic, a full-time member of staff (SH) is employed specifically to oversee weight-loss programs, enabling more intensive supervision than is possible in many firstopinion practices. This may, to an extent, counteract the problems faced by the population of dogs referred. Thus, the results of the current study may not be completely representative of what may be expected in general practice. There are many possible reasons for why weight loss in client-owned dogs may be slower than in colony dogs, including differences in signalment, exercise levels, ambient temperature, concurrent illness, and issues of compliance with the dietary regime. Previous work with colony dogs demonstrated breed differences in the level of energy restriction required to achieve the same rate of weight loss, with Labradors requiring a greater level of restriction than Beagles.g Age, sex, neuter status, and activity level also were shown to be of importance. Indeed, the latest National Research Council guidelines on nutrient requirements for dogs suggested that energy requirements differ among groups.22 Active colony dogs have a higher daily MER (130 kcal/kg BW0.75) than older or inactive pet dogs (95–105 kcal/kg BW0.75), whereas the requirements for young colony dogs may be higher still (140–220 kcal/kg BW0.75).22 It is noteworthy that the range in energy allocation required for satisfactory weight loss in the current study (50–82% MER at TBW) was similar to that reported in previous colony studies when using a similar diet (50–87% MER at TBW).6–8 However, it should be emphasized that the total number of calories actually consumed by dogs in the current study is lower because the MER for pet dogs was used (105 kcal/kg BW0.75). If the maintenance energy equation from the colony studies (132 kcal/kg BW0.73) had been used, then the equivalent range of energy allocations for dogs of the current study would have been 42–70% MER at TBW. This suggests that not only is the rate of weight loss slower for client-owned dogs on a weight-loss program but that energy must be restricted to a greater degree. One notable conclusion of the current study was the wide variability of energy allocation requirements to achieve satisfactory weight loss among dogs (50–82% MER TBW). The reasons for such a discrepancy are unclear but may be attributed to different environmental factors and demographics. This highlights the importance of tailoring the program to the individual and being prepared to make changes if the weight loss does not progress satisfactorily. This issue is highlighted by the fact that 14 of 19 dogs of the current studies required at least one alteration in their weight-loss program. We estimated the degree of dietary noncompliance in each dog from diary records maintained by the owner, and results suggested marked variability in its contribution to overall daily intake. Although overall energy consumption from this source was minor in many cases (eg, ,1% MER TBW in 9/19 dogs), reported supplemental feeding was a particular concern in some dogs, resulting in .3% MER TBW in 4 dogs. However, the true caloric contribution from noncompliance may actually be greater, given the suspected underreporting from owners, and this was an acknowledged limitation of human studies that use such an approach.23 Such a possibility was highlighted by the least successful dog in the current program, where the owner admitted noncompliance yet no record was maintained. A further limitation was the method of estimating the caloric intake from extras, which was with reference to human ‘‘calorie counter’’ guides and information supplied by pet food companies. Imprecision in the figures was possible, given that listed figures were based on an average portion size and owners were not always precise about the exact amounts of food consumed. Nevertheless, the 3 dogs with the greatest reported energy contributions from extras, all successfully achieved their TBWs. This is probably because knowledge of the supplemental feeding enabled us to rectify the problem by advising the owners to reduce the noncompliance in subsequent weeks or by reducing the amount of diet Weight Loss in Dogs food fed. Thus, to ensure predictable weight loss, clinicians should strive to prevent such unwanted calories as much as possible. However, because giving treats is an important part of pet ownership, it can be sanctioned, as long as the clinician maintains a record so that it can be factored into the total daily allowance for the dog. In the current study, sex differences were suggested, with entire male dogs needing less marked restriction, although these were not significant at the P , .01 level. However, it is possible that the small study numbers resulted in insufficient statistical power and that the true effect was missed. This supposition is supported by the findings of previous work that demonstrated similar sex influences on the degree of energy restriction for successful weight loss.24 Thus, the current practice of commencing weight-loss regimes at different energy allocation levels dependent upon sex and neuter status is appropriate. Other than sex, there were no other strong predictors of either the rate of weight loss or the level of energy allocation required; hence, with clientowned dogs, clinicians must monitor the program closely and make alterations whenever required. In keeping with the results of experimental studies that used a diet of similar composition, the majority (.80%) of tissue mass lost by dogs in this study was adipose tissue, with smaller, although significant, losses of lean tissue and BMC. In the current study, the main factor associated with the amount of lean tissue lost was the overall percentage weight loss in that dogs who lost a greater proportion of body weight lost more lean tissue. In contrast to work in cats and humans,13–15 the rate of weight loss and the degree of caloric restriction did not have a significant impact on the proportion of lean and fat lost. The reasons for this discrepancy were not clear but could relate to the relatively slower rate of weight loss for dogs in this study compared with the work in other species. Incorporating exercise in weightloss programs has been shown to assist in lean tissue preservation during weight loss in human patients.25,26 However, this factor was not examined during the current study. In summary, the current study demonstrated that successful weight loss in obese dogs was feasible in clinical practice by using a conventional approach with dietary caloric energy restriction and increased activity. However, marked caloric energy restriction is required, and the rate of weight loss is slower than in equivalent experimental studies. The main predictor of the amount of lean tissue lost was the overall percentage weight loss, suggesting that this may be inevitable in animals required to lose a large proportion of their body mass. e f Salter, Tonbridge, UK Minitab v14.0; Minitab Inc, Quality Plaza, State College, PA g Bissot T, Servet E, Biourge V. Energy allowance to induce weight loss is affected by breed and sex but not diet. Proceedings of the 10th Congress of the European Society of Veterinary and Comparative Nutrition, Nantes, France 2006:188 (abstract) Acknowledgments The authors thank the referring veterinarians for referring cases, and the clinical staff at the University of Liverpool for assistance with case management. Eric Servet, Renaud Sergheraert, and John Rawlings are acknowledged for their assistance. AG’s senior lectureship is funded by Royal Canin. This study was funded by a grant from WALTHAM.

Journal

Journal of Veterinary Internal MedicineWiley

Published: Nov 1, 2007

Keywords: ; ;

References

  • Changes in the body composition of cats during weight reduction by controlled dietary energy restriction
    Butterwick, RF; Markwell, PJ.
  • The calorie, carb and fat bible
    Kellow, JWR.

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