Link to this article: http://journals.cambridge.org/abstract_S1478061504000118How to cite this article: JJ Thomason, WW Bignell, D Batiste and W Sears (2004). Effects of hoof shape, body mass and velocity on surface strain in the wall of the unshod forehoof of Standardbreds trotting on a treadmill. AbstractThe 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 21 . Analysis of variance (ANOVA) of principal compressive strains 1 2 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 1 2 . Multiple regression of 1 2 on these variables gave equations which accurately predicted 1 2 within 3%, but the individual coefficients did not accurately describe how each variable affected 1 2 . Further tests using bivariate regression gave equations that enabled 1 2 data to be standardized for BM and V at the gauge locations used here. Strain 1 2 increased linearly with mass and curvilinearly with velocity (1 2 / V þ V 2 ), 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 1 2 will need a considerably larger sample size than that used here.