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SummaryThe objective of this study was to compare swing phase phase kinetics in the equine forelimb under three shoeing conditions: unshod, flat shoes, eggbar shoes. Flat shoes and eggbar shoes were matched for weight. A 60 Hz video camera recorded a full trotting stride in the sagittal plane during three passes per horse for each shoeing condition. A general linear model ANOVA, treating the horse as a random variable was used to detect differences (p <0.05) between shoeing conditions. All of the joints showed significant differences in net joint moments and energy bursts, between the two shod conditions versus unshod, but differences were not evident between flat shoes and eggbar shoes. When the horses were shod the elbow flexors generated more energy in the early swing phase in order to overcome the increased inertia associated with the weight of the shoes; and the elbow extensors generated more energy in late swing phase to overcome the increased momentum of the shod hoof as it was swung forward. In the distal limb in the early swing phase, energy absorption increased on the extensor (dorsal) aspect, to control joint flexion, and in the late swing phase on the flexor (palmar) aspect to control forward motion and extension. It is concluded as a consequence of changing the inertial parameters of the hoof that the weight of the shoes altered the limb kinetics of trotting horses.

A pilot study was performed using a strain gauge transducer intercalated between the bit and the left rein to measure rein tension dynamically during riding. The strain patterns consisted of a series of spikes with frequencies corresponding to two per stride in walk and trot and one per stride in canter. The highest tension recorded in each gait was 43 N at walk, 51 N at trot and 104 N in canter. Based on the results of this study, it is recommended that the methodology should be adapted so that both reins are instrumented simultaneously, data are transmitted telemetrically to eliminate the need for a tether connecting the horse to the computer, and kinematic data are synchronized with the rein tension recordings.

SummaryThe objectives were to measure sagittal plane kinematics and kinetics of the forelimb pastern joint during the stance phase at the trot. Sagittal plane video (200 Hz) and force (1,000 Hz) recordings were analyzed from four trials of six sound horses trotting in hand. Kinematic and force data were used to calculate net joint moments and joint powers. The pastern joint showed maximal flexion (155.3 ± 11.0°) at 34% stance and maximal extension (190.2 ± 3.8°) at 93% stance. Energy was absorbed on the palmar aspect throughout stance, with peak energy absorption occurring in the second half of the stance. It was concluded that the primary function of the pastern joint was to act as an energy damper.