The equine hoof lamellae are weakened and frequently damaged by laminitis, and the third phalanx (P3) can become abnormally, permanently displaced. Shoes are often utilized to stabilize hoof components and P3. The tested hypothesis was that shoe configuration differently affects unaffected versus laminitic hoof component motion. Unaffected and laminitic forelimbs (8/condition) were disarticulated and embedded within fixtures following fixation of the proximal interphalangeal joint. A mechanical testing system was used to apply compressive force up to 5,500 N. A real-time motion detection system recorded 3-D Cartesian coordinates of markers fafixed on the P3, dorsal hoof wall (HW), coronary band (CB), and solar margin (SM). Hoof component motion with and without open-heel, heart-bar and egg-bar shoes was compared with a repeated measures analysis. During loading, P3, HW, CB, and SM displaced more in laminitic than unaffected hooves, and the hoof capsule showed an overall compression. Egg-bar and heart-bar shoes decreased P3 displacement in laminitic hooves and prevented motion away from the HW. P3 moved towards the SM with open-heel and egg-bar shoes in all hooves. Heart-bar shoes minimized P3 motion and structural deformation of laminitic hooves while reducing P3 sinking in unaffected hooves. Results highlight distinct effects of shoes on quantity and direction of hoof component motion in unaffected versus laminitic hooves. This study was limited by the ex vivo nature of the work. Study results underline the distinct impact of shoe configuration on laminitic hoof tissue, an important consideration during selection of shoes to protect weakened hoof tissue.
