The effect of the aqua-treadmill on the kinematics of the equine axial skeleton

Equine aqua-treadmills are increasingly popular for training and rehabilitating horses from injury, yet relatively little research exists reporting on the changes in back kinematics when working horses through water. This current PhD research aims to provide some quantitative analysis of the movement of the axial skeleton when the horse is trotting on the aqua-treadmill at a series of increasing water depths, with the aim of informing practices. Current work has investigated vertical displacements of anatomical landmarks along the back, focussing on the withers and pelvis, as water depth is increased. Vertical displacement of both the pelvis and withers has been shown to increase significantly as water depth increases; however, the vertical displacement of the withers is significantly less than that of the pelvis suggesting that the forelimbs can compensate with the increased water depth by being able to bend at the knee. Additionally, as water depth increased, horses started the stride significantly lower, suggesting an increase in hindlimb compression to increase ‘push off’ and therefore vertical lift. Further work has started to investigate the medio-lateral changes of the spine as water depth is increased. Published findings are anticipated to have an overall positive impact on equine rehabilitative techniques.