Resumen de Comparison of limb loading and movement of Icelandic horses while tölting and trotting at equal speeds
Nina M. Waldern, Thomas Wiestner, Lea C. Ramseier, Michael A. Weishaupt
Comparison of limb loading and movement of Icelandic horses while tölting and trotting at equal speeds Nina M. Waldern, Dr Med Vet, PhD; Thomas Wiestner, EL ING HTL; Lea C. Ramseier, Dr Med Vet; Michael A. Weishaupt, Dr Med Vet, PhD Equine Department, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland. (Waldern, Wiestner, Ramseier, Weishaupt); Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland. (Waldern) Dr. Ramseier's present address is Equine Department, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
Address correspondence to Dr. Weishaupt (mweishaupt@vetclinics.uzh.ch).
OBJECTIVE To compare gait mechanics and limb loading in Icelandic horses tölting 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 tölt 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 tölt than at a trot. For forelimbs at a tölt, 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 tölt 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 tölt, and the inverse was observed at a trot. Minimal height of the horse's trunk at the point of Fzpeak of the respective limb suggested a spring-like mechanism for all limbs at a tölt. Hind limb measurements revealed no evidence of increased collection. Stride-to-stride limb timing varied more at a tölt than at a trot. At a trot, horses had brief or no suspension phases and a slightly 4-beated footfall rhythm was common. Post hoc energetic estimations revealed that tölting at the measured speeds was less advantageous than trotting.
CONCLUSIONS AND CLINICAL RELEVANCE High forelimb action in Icelandic horses and higher head-neck position at a tölt were associated with more restricted limb proretraction, higher Fzpeak, and faster force onset than at a trot. The impact of these differences on orthopedic health needs to be investigated more in detail.
