Morphometric changes in overweight horses following 10-week weight loss programs.

Abstract

BACKGROUND: Up to 70% of horses in domestic equine populations are overweight. Promotion of weight loss is an important component of limiting the detrimental co-morbidities associated with excess adipose tissue. The use of a body condition score (BCS) can help equine caregivers track their horse's weight-status. However, this single score doesn't reflect changes in individual adipose depots. The purpose of this study was to characterize morphometric changes (including 8 anatomic BCS measurements that make up the whole-BCS) in horses during 3 different weight-loss programs over 10 weeks. METHODS: Thirty-two horses were randomly assigned to one of three weight loss groups [exercise (E; fed to 100% digestible energy (DE) requirements, exercise 5x/week), feed restriction (FR; fed to 85% DE requirements, no exercise), or feed restriction and exercise (FRE; 85% DE, exercise 5x/week)], or a weight-maintained control (C; 100% DE, no exercise)] for 10 weeks. Horses were fed individualized diets formulated to meet their nutritional requirements. Outcome measures were recorded at weeks 1, 5 and 10, and included 11 morphometric measurements [body weight (BW) via weight tape, cresty neck score (CNS), and 8 individual BCSs (neck, shoulder, leg, withers, ribs, back, haunches, and tailhead) and a whole-BCS)]. Data were analyzed using a 2-Way RM ANOVA with respect to treatment group and week. RESULTS: All 4 groups (including controls) had a significant reduction in BW and whole BCS. At week 10 whole BCS was lower in FRE than controls. All groups had a reduction in back, haunches, leg and shoulder; FR, FRE and E horses had reductions in rib BCS; E and FRE horses had reductions in tailhead BCS and CNS. CONCLUSION: In conclusion, all weight loss strategies produced significant weight loss, but only those strategies which included exercise reduced fat deposits known to be implicated in metabolic dysregulation in obese horses. Future studies should explore the optimum exercise load (duration and intensity) to facilitate loss of fat from these areas.