Kinematics in horses at the trot before and after an induced forelimb supporting lameness

The aim of this study was to analyse the biokinematic alterations caused by an induced lameness in the right forelimb of Dutch Warmblood (DWB) horses using a system of computer-aided normal videography. Five mature DWB were recorded with a videocamera (frame rate 1/25) from a lateral view before and after an induced lameness. Before videotaping, passive markers were placed on the skin, over easily identifiable anatomical references to determine the joint angles in the forelimb (always on the flexor side). Lameness was induced using special horseshoes. The lameness was evident at the trot and mild at walk. The images were analysed using a real time digitalising system combined with a previously designed spreadsheet. Linear, temporal and angular parameters (maximum, minimum and angular range of motion) along the stride were calculated as well as the moments of highest extension (Pmax) and flexion (Pmin), expressed as a percentage of the whole stride. Results before and after the induced lameness were compared by a paired Student's t test at a significance level of P<0.05. No differences in speeds before and after the induced lameness were found. Stride length was significantly shorter in the lameness condition. Stride duration was slightly shorter in lameness. The diagonal stance phase increased, while the swing phase decreased. Angular parameters changed mainly in elbow, carpus, fetlock and retraction-protraction angles. This indicated that the angular range of motion in the elbow and carpal joints decreased, and the elbow Pmin occurred later in the stride. The results are useful in the development of video-based equine lameness diagnostics.