Effect of Gait and Turn Direction on Body Lean Angle in the Horse

Abstract

IntroductionTurning is commonly used as a diagnostic aid in lameness examinations. Systematic movement deviations compared to locomotion in a straight line are noted across horses with variation at an individual level. This study aimed to investigate whether deviations from the expected body lean angle, predicted from the ratio of gravitational and centripetal accelerations, are consistent between trot and canter. It was hypothesized that, independent of gait, there would be agreement between the observed and predicted angle with variations on an individual horse level.MethodsA GPS‐aided inertial measurement unit was attached over the sacrum in twenty horses and quantified body lean angle, speed and circle radius in trot and canter on left and right rein. Predicted body lean angle was calculated from speed and circle radius and was compared to the observed body lean (Δobs,pred). A generalized linear model was implemented to study the effect of horse, lungeing direction and gait.ResultsMean speed and circle radius were 3.3 m/s and 4.9 m in trot and 4.5 m/s and 5.7 m in canter. On average Δobs,pred was −1.1°in trot and −0.8°in canter and was found to be significantly different between horses (P<0.0001) and between lungeing directions (P<0.0001) but not between gaits (P = 0.14). Interactions between horse and direction (P<0.0001) and horse and gait (P = 0.011) were also found to be significant.ConclusionsHorses leaned marginally less into the circle than predicted. However, showing significant differences in body lean angle between horses and turn directions but not between gaits, we provide evidence for horse specific adaptations. Whether these are related to laterality or to underlying subclinical lameness needs to be further investigated.Ethical Animal ResearchThe study was approved by the local ethics committee. Sources of funding: none declared. Competing interests: none.