Thilo Pfau

Background Horseshoes with modified contact surfaces combined with deformable ground substrates are used to change hoof orientation during mid‐stance, for example, for therapeutic reasons. Objectives To measure the effect of horseshoes and ground substrates on sagittal and transverse plane hoof orientation at mid‐stance using a dorsal hoof wall mounted triaxial accelerometer. Study design In vivo experiment, randomised crossover design. Methods Differences in sagittal and transverse plane angles between standing and mid‐stance of the left front hoof of six horses walking with regular horseshoes, egg bar, toe‐wide, medial‐wide, lateral‐wide and three‐degree egg bar shoes on turf, sand and hard ground substrates were assessed with linear mixed models with horseshoe and substrate type as fixed factors ( p < 0.05) for each animal. Results Hoof angles were significantly affected by horseshoe ( p < 0.001), surface ( p < 0.001) and the combination ( p < 0.001). The sagittal plane angle increased in deformable ground substrates at walk‐in mid‐stance on turf [mean (±standard deviation): 2.6° (±3.8°)] and on sand [2.6° (±4.1°)] across all shoes. The greatest increase was observed with egg bar shoes [turf: 4.37° (±3.82°); sand 4.69° (±3.83°)]. There was a tendency for the hoof to sink laterally into deformable ground substrates among all shoes [turf: 1.11° (±1.49°); sand: 0.93° (±1.93°)]. Medial‐wide shoes increased the lateral sinking [turf: 2.00° (±1.63°); sand: 1.79° (±1.58°)]. Lateral‐wide shoes reduced the lateral sinking on turf [0.62° (±1.26°)] and induced a marginal medial sinking on sand [−0.007° (±2.03°)]. Main limitations The substrate properties were not quantitatively assessed, and observations were limited to front hooves at the walk. A larger sample size would be preferable. Conclusions Mid‐stance hoof orientation changes with specific combinations of shoes and ground substrates in the walking horse.