Resumen de Use of a novel morphometric method and body fat index system for estimation of body composition in overweight and obese dogs
Objective—To develop morphometric equations for prediction of body composition and create a body fat index (BFI) to estimate body fat percentage in overweight and obese dogs.
Design—Prospective evaluation study.
Animals—83 overweight or obese dogs ≥ 1 year of age.
Procedures—Body condition score (BCS) was assessed on a 5-point scale, morphometric measurements were made, and visual and palpation-based assessments and dual-energy x-ray absorptiometry (DEXA) were performed. Equations for predicting lean body mass, fat mass, and body fat as a percentage of total body weight (ie, body fat percentage) on the basis of morphometric measurements were generated with best-fit statistical models. Visual and palpation-based descriptors were used to develop a BFI. Predicted values for body composition components were compared with DEXA-measured values.
Results—For the study population, the developed morphometric equations accounted for 98% of the variation in lean body mass and fat mass and 82% of the variation in body fat percentage. The proportion of dogs with predicted values within 10% of the DEXA values was 66 of 83 (80%) for lean body mass, 56 of 83 (68%) for fat mass, and 56 of 83 (67%) for body fat percentage. The BFI accurately predicted body fat percentage in 25 of 47 (53%) dogs, whereas the value predicted with BCS was accurate in 6 of 47 (13%) dogs.
Conclusions and Clinical Relevance—Morphometric measurements and the BFI appeared to be more accurate than the 5-point BCS method for estimation of body fat percentage in overweight and obese dogs. Further research is needed to assess the applicability of these findings to other populations of dogs. (J Am Vet Med Assoc 2014;244:1279–1284) Excess weight and obesity have become more common in pet dogs in recent years.1 Results of studies2–4 in the past 10 years have indicated that approximately 30% to 40% of pet dogs are overweight and approximately 5% to 20% are obese. As in humans, obesity in dogs is associated with a variety of health problems, such as insulin resistance, orthopedic disorders, cardiorespiratory disease, urogenital dysfunction, neoplasia, and several functional alterations (eg, decreased ability to exercise).4–6 Therefore, dietary and lifestyle management is needed for many pet dogs to help them reach and maintain a healthy weight.
Unfortunately, owners are often poor judges of their pet's body condition, especially when their pet is obese or overweight.7,8 Veterinarians need to be able to judge body composition and ideal weight to develop feeding plans, but no accurate, noninvasive measures of body condition are available to veterinarians in the clinic. A precise measure of body composition can be obtained by means of DEXA,9 but the equipment is expensive, often unavailable to veterinarians in clinical practices, and impractical for routine use. Portable bioimpedance monitors are noninvasive devices that can be used to assess body fat content in dogs, but these are inaccurate for measurements in very obese dogs.10 Although a BCS can be a useful tool in management of body weight in pets, BCS systems are subjective and group all obese dogs together, irrespective of the extent of obesity. These systems rely on palpation and visual assessment to assign a score to patients where low and high scores equate to low and high amounts of body fat, respectively. The 2 BCS systems commonly used in practice involve use of a 5-point scale and a 9-point scale.11,12 Both of these scales were validated in animals with < 45% body fat, and on the basis of the authors' clinical experience, the number of morbidly obese animals with > 45% body fat appears to be increasing.
Equations based on morphometric measurements have been used to predict body fat percentage in dogs.13,14 However, these equations have been tested and developed only for dogs with body fat comprising approximately 40% or less of body weight. The purpose of the study reported here was to develop equations for accurately predicting lean body mass, fat mass, and body fat as a percentage of weight (ie, body fat percentage) on the basis of morphometric measurements and to develop a BFI system that combines results of palpation and visual assessment to accurately predict body fat percentages in overweight or obese dogs, with DEXA used as a reference standard. We also aimed to evaluate use of the 5-point BCS for estimation of body fat percentage and compare its accuracy with that of the newly developed methods.
