The influence of different horseshoes and ground substrates on mid-stance hoof orientation at the walk

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 degrees (+/- 3.8 degrees)] and on sand [2.6 degrees (+/- 4.1 degrees)] across all shoes. The greatest increase was observed with egg bar shoes [turf: 4.37 degrees (+/- 3.82 degrees); sand 4.69 degrees (+/- 3.83 degrees)]. There was a tendency for the hoof to sink laterally into deformable ground substrates among all shoes [turf: 1.11 degrees (+/- 1.49 degrees); sand: 0.93 degrees (+/- 1.93 degrees)]. Medial-wide shoes increased the lateral sinking [turf: 2.00 degrees (+/- 1.63 degrees); sand: 1.79 degrees (+/- 1.58 degrees)]. Lateral-wide shoes reduced the lateral sinking on turf [0.62 degrees (+/- 1.26 degrees)] and induced a marginal medial sinking on sand [-0.007 degrees (+/- 2.03 degrees)]. 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.