Noninvasive measurements of body composition and body water via quantitative magnetic resonance, deuterium water, and dual-energy x-ray absorptiometry in awake and sedated dogs

Inferring condition in wild mammals: body condition indices confer no benefit over measuring body mass across ecological contexts

Many studies assume that it is beneficial for individuals of a species to be heavier, or have a higher body condition index (BCI), without accounting for the physiological relevance of variation in the composition of different body tissues. We hypothesized that the relationship between BCI and masses of physiologically important tissues (fat and lean) would be conditional on annual patterns of energy acquisition and expenditure. We studied three species with contrasting ecologies in their respective natural ranges: an obligate hibernator (Columbian ground squirrel, Urocitellus columbianus), a facultative hibernator (black-tailed prairie dog, Cynomys ludovicianus), and a food-caching non-hibernator (North American red squirrel, Tamiasciurus hudsonicus). We measured fat and lean mass in adults of both sexes using quantitative magnetic resonance (QMR). We measured body mass and two measures of skeletal structure (zygomatic width and right hind foot length) to develop sex- and species-specific BCIs, and tested the utility of BCI to predict body composition in each species. Body condition indices were more consistently, and more strongly correlated, with lean mass than fat mass. The indices were most positively correlated with fat when fat was expected to be very high (pre-hibernation prairie dogs). In all cases, however, BCI was never better than body mass alone in predicting fat or lean mass. While the accuracy of BCI in estimating fat varied across the natural histories and annual energetic patterns of the species considered, measuring body mass alone was as effective, or superior in capturing sufficient variation in fat and lean in most cases.

Body Condition and Fertility in Dogs

Ideal body condition and nutritional status in dogs is essential for quality of life, including reproductive health. Herein, we review the implications body condition, particularly fat, has on puberty, fertility, pregnancy, and parturition in dogs. Ideal body condition at puberty is necessary for dogs to achieve sexual maturity and reproduce. Moreover, over and under conditioned female dogs have increased risk of adverse pregnancy, parturition, and neonatal outcomes. Less is known about body condition and male dog fertility but some evidence is provided in this article. Finally, recommendations for maintaining an ideal body condition in intact adult dogs for optimal fertility are provided.

Evaluation of the use of muscle condition score and ultrasonographic measurements for assessment of muscle mass in dogs

OBJECTIVE

To evaluate repeatability and reproducibility of muscle condition score (MCS) in dogs with various degrees of muscle loss; to compare MCS, muscle ultrasonographic measurements, and quantitative magnetic resonance (QMR) measurements; and to identify cutoff values for ultrasonographic measurements of muscle that can be used to identify dogs with cachexia and sarcopenia.

ANIMALS

40 dogs of various age, body condition score (BCS), and MCS.

PROCEDURES

A prospective cross-sectional study was conducted. Body weight, BCS, QMR measurements, thoracic radiographic measurements, and muscle ultrasonographic measurements were assessed once in each dog. The MCS for each dog was assessed 3 separate times by 4 separate raters.

RESULTS

For the MCS, overall κ for interrater agreement was 0.50 and overall κ for intrarater agreement ranged from 0.59 to 0.77. For both interrater and intrarater agreement, κ coefficients were higher for dogs with normal muscle mass and severe muscle loss and lower for dogs with mild and moderate muscle loss. The MCS was significantly correlated with age (r = -0.62), vertebral epaxial muscle score (VEMS; r = 0.71), forelimb epaxial muscle score (FLEMS; r = 0.58), and BCS (r = 0.73), and VEMS was significantly correlated (r = 0.84) with FLEMS. Cutoff values for identification of mild muscle loss determined by use of VEMS and FLEMS were 1.124 and 1.666, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

MCS had substantial repeatability and moderate reproducibility for assessment of muscle mass in dogs. Prospective studies of MCS, VEMS, and FLEMS for assessment of muscle mass in dogs are warranted.

Body fat assessment by computed tomography and radiography in normal Beagle dogs

The purpose of this study was to determine the relationships among body condition score (BCS), radiography, and computed tomography (CT), and to establish a method for body fat assessment on CT in dogs. Thirty eight Beagles with 2 to 7 BCS were examined. Subcutaneous fat thickness (ST) on radiograph and body area (BA), total fat area (TA), subcutaneous fat area (SA), and visceral fat area (VA) on CT were measured at the level of L3 and L6 vertebra. Ratios of each value to the L6 length were obtained (_rST, _rTA, _rSA, _rVA) and the correlations with BCS were estimated. The value of VA/SA, VA/TA, TA/BA, VA/BA, and SA/BA were selected for measuring fat and the correlations with BCS were estimated. The _rST, _rTA, _rSA, and _rVA were significantly correlated with BCS, and the _rTA and _rSA were significantly correlated with _rST. At the level of L3, _rTA and _rVA had stronger relationships with BCS than at L6 while _rSA had a higher correlation with BCS at L6. The TA/BA, VA/BA, and SA/BA were significantly correlated with BCS, and the upper limits were 15.11, 6.31, and 8.92%, respectively. Our results showed that CT could be useful to assess body fat and TA/BA, VA/BA, and SA/BA are suitable criteria for measuring fat on CT. In addition, L3 was a more suitable location for evaluating total and visceral fat, and L6 was more suitable for evaluating subcutaneous fat.

Effect of neuroactive nutritional supplementation on body weight and composition in growing puppies

Nutritional factors can dramatically affect development of young animals during the early stage of life. The objective of the present study was to examine the effects of a neuroactive nutritional supplement (NNS) containing DHA, taurine, carotenoids and vitamins on the body weight and body composition of growing puppies. A total of twenty-four 2-month-old Beagles were fed a nutritionally complete and balanced base diet and a control supplement daily during an initial 1-month baseline assessment, after which they were divided into control and treatment groups. They were fed daily either control or treatment supplements in addition to the base diet from 3 to 12 months of age. Lean body mass and fat mass were assessed using quantitative magnetic resonance scans at 0 (baseline), 3, 6 and 9 months of treatment. Total body weight and lean body mass did not differ between groups over time. The puppies in the treatment group showed a trend of reduced fat gain compared with those in the control group, and with a marginally significant difference at 6 months (P = 0·05). At 3 months, insulin-like growth factor 1 was higher (P = 0·02) in the treatment group compared with the control group. At 9 months, fasting lipid levels were lower (P < 0·05) and fat-oxidation metabolite 3-hydroxybutyrate was higher (P < 0·05) in the treatment group compared with the control group. These results may indicate that NNS has an impact on puppy growth and development, possibly by promoting fat metabolism; further investigation would be necessary to determine the full impact of this supplement on growth and development.

Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry

Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs.

In Vivo Determination of Body Composition in Zebrafish (Danio rerio) by Quantitative Magnetic Resonance

Zebrafish (Danio rerio) as a model research organism continues to expand its relevance and role in multiple research disciplines, with recent work directed toward models of metabolism, nutrition, and energetics. Multiple technologies exist to assess body composition in animal research models at various levels of detail (tissues/organs, body regions, and whole organism). The development and/or validation of body composition assessment tools can open new areas of research questions for a given organism. Using fish from a comparative nutrition study, quantitative magnetic resonance (QMR) assessment of whole body fat and fat-free mass (FFM) in live fish was performed. QMR measures from two cohorts (n = 26 and n = 27) were compared with chemical carcass analysis (CCA) of FM and FFM. QMR was significantly correlated with chemical carcass values (fat, p < 0.001; lean, p = 0.002), although QMR significantly overestimated fat mass (FM) (0.011 g; p < 0.0001) and underestimated FFM (-0.024 g; p < 0.0001) relative to CCA. In a separate cross-validation group of fish, prediction equations corrected carcass values for FM (p = 0.121) and FFM (p = 0.753). These results support the utilization of QMR-a nonlethal nondestructive method-for cross-sectional or longitudinal body composition assessment outcomes in zebrafish.

Body composition during fetal development and infancy through the age of 5 years

Fetal body composition is an important determinant of body composition at birth, and it is likely to be an important determinant at later stages in life. The purpose of this work is to provide a comprehensive overview by presenting data from previously published studies that report on body composition during fetal development in newborns and the infant/child through 5 years of age. Understanding the changes in body composition that occur both in utero and during infancy and childhood, and how they may be related, may help inform evidence-based practice during pregnancy and childhood. We describe body composition measurement techniques from the in utero period to 5 years of age, and identify gaps in knowledge to direct future research efforts. Available literature on chemical and cadaver analyses of fetal studies during gestation is presented to show the timing and accretion rates of adipose and lean tissues. Quantitative and qualitative aspects of fetal lean and fat mass accretion could be especially useful in the clinical setting for diagnostic purposes. The practicality of different pediatric body composition measurement methods in the clinical setting is discussed by presenting the assumptions and limitations associated with each method that may assist the clinician in characterizing the health and nutritional status of the fetus, infant and child. It is our hope that this review will help guide future research efforts directed at increasing the understanding of how body composition in early development may be associated with chronic diseases in later life.

Whole Body Computed Tomography with Advanced Imaging Techniques: A Research Tool for Measuring Body Composition in Dogs

The use of computed tomography (CT) to evaluate obesity in canines is limited. Traditional CT image analysis is cumbersome and uses prediction equations that require manual calculations. In order to overcome this, our study investigated the use of advanced image analysis software programs to determine body composition in dogs with an application to canine obesity research. Beagles and greyhounds were chosen for their differences in morphology and propensity to obesity. Whole body CT scans with regular intervals were performed on six beagles and six greyhounds that were subjected to a 28-day weight-gain protocol. The CT images obtained at days 0 and 28 were analyzed using software programs OsiriX, ImageJ, and AutoCAT. The CT scanning technique was able to differentiate bone, lean, and fat tissue in dogs and proved sensitive enough to detect increases in both lean and fat during weight gain over a short period. A significant difference in lean : fat ratio was observed between the two breeds on both days 0 and 28 (P < 0.01). Therefore, CT and advanced image analysis proved useful in the current study for the estimation of body composition in dogs and has the potential to be used in canine obesity research.