Comparison of limb loading and movement of Icelandic horses while tölting and trotting at equal speeds

OBJECTIVE To compare gait mechanics and limb loading in Icelandic horses tolting and trotting at equal speeds and estimate their impact on orthopedic health. ANIMALS 12 orthopedically normal Icelandic horses. PROCEDURES Kinetic and kinematic gait variables were simultaneously recorded as each horse was ridden at a tolt and trot on an instrumented treadmill at 3.4 m/s and 3.9 m/s. Differences between gaits were tested via 1-factor repeated-measures ANOVA. RESULTS Horses had a higher stride rate and lower stride impulses at a tolt than at a trot. For forelimbs at a tolt, shorter relative stance duration resulted in higher peak vertical force (Fzpeak). Conversely, for hind limbs, longer relative stance duration resulted in lower Fzpeak. The higher head-neck position at a tolt versus trot caused no weight shift to the hind limbs, but a higher forehoof flight arc and lower proretraction movement were identified. Stance durations for forelimbs were briefer than for hind limbs at a tolt, and the inverse was obse...