Effects of Shoeing on Breakover Forces in Icelandic Horses at Walk, Tölt and Trot

Abstract

IntroductionTo enhance expressiveness and regularity of the tölt, Icelandic horses are commonly shod with excessively high and long hooves. The aim of this study was to objectively assess the effect of shoeing on distal interphalangeal (DIP) joint moments of the left forelimb during break‐over at walk, tölt and trot.MethodsTwelve sound Icelandic horses accustomed to exercise with a rider on a treadmill were assessed with hooves trimmed and shod according to the standards of normal shoeing and with long and high front hooves; besides the 20 x 8 mm steel shoes, this condition included pads and packing material used in competition. Vertical ground reaction forces (GRFz) were measured with an instrumented treadmill. Time of break‐over was determined kinematically. Measuring systems were started synchronously; sampling frequency was 480 Hz. Measurements were taken at 1.34 ± 0.04 m/s (walk), 3.89 ± 0.10 m/s (tölt), and 3.90 ± 0.10 m/s (trot). The DIP joint moment arm was determined on size‐calibrated latero‐medial radiographs of the left front hoof. Differences were tested using a t‐test (walk) or repeated measures ANOVA (tölt, trot).ResultsIn the condition with the long and high hooves, DIP joint moment was increased by 18.5% at walk (P<0.001), 17.3% at tölt (P<0.001) and 13.4% at trot (P = 0.017) although vertical GRFz at break‐over was not statistically different between the two shoeing conditions. The increase could be attributed to the 22.7% increase of the lever arm.ConclusionsHigh hooves with long toes may have negative implications for the health of the palmar structures of the distal foot.Ethical Animal ResearchThe experiment was carried out with the approval of the Animal Health and Welfare Commission of the Canton of Zurich (No. 206/2010). Owners gave informed written consent. Sources of funding: Stiftung Forschung für das Pferd, the Haldimann Stiftung, the Swiss Metall Union, the Stiftung Temperatio, the Swiss Veterinary Office (FVO) and the Islandpferde‐Vereinigung Schweiz. Competing interests: none.