Evaluation of Body Condition Index in Comparison with Body Condition Score in Horses and Ponies

Objective assessment of adiposity may be useful in monitoring health and fitness in performance horses. While relatively accurate and useful for experienced investigators, body condition scoring systems can be subjective and unreliable for inexperienced owners or assessors, underscoring a need for a quantitative, rather than qualitative, index to measure condition. The purpose of this study was to compare the more subjective body condition scoring system (BCS) to the newly developed body condition index (BCI), similar to the body mass index (BMI) used in humans. The BCI was derived iteratively using objective measurements (cm): BCI = [(HB^0.5 + BG + NC^1.2)/H^1.05]^2.2, where HG = heart girth, BG = belly girth, NC = neck circumference, and H = height to the withers. In the current study one hundred twenty-six horses and ponies of varying ages (1 to 26 yr) and breed types (23 Thoroughbred or Thoroughbred crosses, 11 ponies, and 92 warmbloods) were used to compare the BCS and the BMI. Body condition scores (using the modified Henneke scoring system, and assessed by experienced investigators) ranged from 3.5 to 8 out of 9. BCI scores ranged from 4.7 to 8.4 out of 9. Scores were different between the BCI and BCS (P < 0.0001); BCI scores were generally higher with a mean difference of 0.65. While the BCI and BCS were not meant to be exact matches (r = 0.34), it is useful to understand the potential causes of variation between the two systems, and where room for improvement may exist. Mean differences were similar between Thoroughbreds, ponies, and warmblood breeds (0.67, 0.71, and 0.67 respectively), suggesting the BCI does not have a breed bias, and can cross over different confirmation types. Much of the variation may arise from animals with lower BCS scores. In horses and ponies with a BCS greater than or equal to 5, the mean difference between BCI and BCS was 0.51, but in horses with a BCS less than 5, the mean difference was 1.49. These data suggest the BCI equation may need to be adjusted in order to better fit horses with a BCS less than 5.