Kinematic comparison of the leading and trailing fore- and hindlimbs at the canter.

The canter is a 3 beat asymmetrical gait with a difference in timing between left and right limbs. To evaluate intralimb asymmetry at the canter, a group of 24 Dutch Warmbloods was evaluated on a treadmill (7 m/s) using a modified CODA-3 optoelectronic gait analysis system. Thirteen horses cantered in the left lead ('leading limb' group) and 11 in the right lead ('trailing limb' group) during left forelimb recordings, while 11 horses were at the left and 13 were at the right lead during left hindlimb recordings. Kinematic differences between horses from the 'leading limb' and 'trailing limb' group were statistically evaluated at a significance level of P<0.05. Stride, stance and swing duration were similar between the 2 groups. The pelvis rotation, angle of maximal protraction and total range of maximal pro- and retraction were larger in the 'leading limb' group, while the scapula rotation, and the angle of maximal retraction were larger in the 'trailing limb' group. The elbow and hip joints were more flexed at impact, at maximal extension and at maximal flexion of the leading limb, whereas the stifle joint was more extended at impact. Furthermore, the leading tarsal joint was more maximally flexed in stance and swing phase, whereas the carpal joint was more flexed only in the swing phase of the leading limb. However, during the stance phase the maximal fetlock extension of the trailing fore- and hindlimbs were significantly larger. Apparently, horses move at the canter with a more protracted leading limb by more flexing the elbow, carpal, hip and tarsal joints. In the trailing limb, however, the scapula is more rotated, and the tarsal and fetlock joints are more loaded. In conclusion, the difference in interlimb timing between left and right limbs at canter also leads to an asymmetry in intralimb coordination of these limbs.