Validation of a body condition scoring system in rhesus macaques (Macaca mulatta): assessment of body composition by using dual-energy X-ray absorptiometry.

Body condition scoring (BCS) is a subjective semiquantitative method of assessing body fat and muscle by palpation of key anatomic features. A previously published BCS system for rhesus macaques (Macaca mulatta) uses a scale comprising both whole and half units, in which the midrange represents optimal body condition (3.0), lower values represent emaciated to lean conditions (1.0 to 2.0), and higher values (4.0 to 5.0) indicate excessive body fat. A valid BCS system is well described, relevant to the species, has agreement within and between raters, and is consistent with objective measures. Here we correlate the subjective BCS assigned during physical exam with percentage body fat as determined by dual-energy X-ray absorptiometry (DEXA). Adult rhesus monkeys from an indoor-housed breeding colony were evaluated by the veterinary staff and assigned to 1 of 9 BCS score groups to give a minimum of 6 animals in each group. DEXA was used to obtain objective body composition measurements for macaques in each BCS group. Animals in the 'optimal' BCS group (3.0) had 25% body fat on average. Each full unit change in BCS was associated with an approximate 10% change in body fat percentage for macaques in the 2.0-to-5.0 BCS range. Absolute body fat in animals with BCS of 1.0 or 1.5 may be too low for accurate assessment by DEXA.