Published online by Cambridge University Press: 09 March 2007
The purpose of this work is to investigate the effects of body mass (BM), velocity (V), and hoof shape on compressive surface strains in the wall of the front hoof at the trot. Toe angle (TA), heel angle (HA), toe length (TL), medial and lateral wall length (MWL, LWL) and BM were measured for nine adult, unshod Standardbreds. Five rosette gauges were glued around the circumference of the left forehoof of each animal which was then trotted on a treadmill at a set range of velocities from 3.5 to 7.5 m s−1. Analysis of variance (ANOVA) of principal compressive strains ɛ2 at midstance identified that all primary variables (BM, V, TA, HA, etc.) had a significant effect as did the interactions of TA×HA and BM×TA. These significant variables explained over 96% of the variation in ɛ2. Multiple regression of ɛ2 on these variables gave equations which accurately predicted ɛ2 within 3%, but the individual coefficients did not accurately describe how each variable affected ɛ2. Further tests using bivariate regression gave equations that enabled ɛ2 data to be standardized for BM and V at the gauge locations used here. Strain ɛ2 increased linearly with mass and curvilinearly with velocity (ɛ2∝V+V2), and both caused redistribution of strain to the dorsum and lateral quarter. Variation in each shape variable caused redistribution rather than simple increase or decrease in strains. The primary conclusion with regard to hoof shape is that the effects of change in any one measurement on strain magnitudes are affected by the values of all other measurements. Resolving the interplay among measurements in their effects on ɛ2 will need a considerably larger sample size than that used here.