The Influence of Lameness on Equine Stride Length Consistency*

The aim of this study was to assess the influence of orthopaedic pain on the variation of stride length as a kinematic system-parameter in 21 horses with forelimb lameness. Data were collected while the horses were trotting on a treadmill during a minimum of 12 motion cycles, both before and after intra-articular or perineural anaesthesia. Stride length was assessed for each motion cycle, and the mean and standard deviation were calculated for each condition. Forelimb lameness was documented as percentage of asymmetry of vertical head movement. With significant decrease of forelimb lameness after regional anaesthesia, the SD of stride length increased significantly (+0.35%, P< 0.05). Our results show that in the presence of orthopaedic pain horses keep stride variability low, possibly because the lame horse employs an optimum compensatory mechanism to reduce the pain in the affected limb, and every deviation from this pattern increases pain.