Comparison of pressure plate and force plate gait kinetics in sound Warmbloods at walk and trot.

Modern pressure plates (PP) could be an alternative to traditional force plates (FP) for quantitative equine gait analysis, thereby providing the clinician with objective data on the horse's gait while unravelling the loading of different regions of the hoof during the stance phase. The aim of this study was to determine whether a stand-alone PP allows reliable measurement of gait kinetics, compared to simultaneously recorded FP variables. Six sound Warmblood horses were walked and trotted over a combined PP and FP system for collection of a set of five valid kinetic measurements for each forelimb. A measurement was considered valid if the horse was moving in a straight line at a constant pace while gait velocity was within a preset range and the hoof fully contacted the plate surface. Significant differences between FP and PP data were seen for peak vertical force (PVF), vertical impulse (VI), time at which the PVF occurs (tPVF) and forelimb symmetry ratios (SymPVF and SymVI) (P < 0.05), but not for stance phase duration (ST). Nevertheless, mean agreement indices (AIs) of ST, tPVF and SymPVF and SymVI were excellent (≥ 0.92), whereas AIs of PVF and VI were moderate (≥ 0.70). The excellent agreement between PP and FP symmetry ratios confirms that observed differences between PP and FP in symmetry ratios are small (2-7%), especially when compared to the expected decrease in symmetry associated with mild lameness (> 20%). The results indicate that a stand-alone pressure plate can be used to measure absolute (ST) and relative (tPVF) temporal variables and loading symmetry ratios and offers equine veterinarians a mobile, cost-efficient and quick gait evaluation method for routine clinical use. However, the system cannot be used interchangeably with a force plate to measure absolute values of limb loading.