The influence of equine hoof conformation on the initiation and progression of laminitis.

Abstract

BACKGROUND: The health and performance of horses are significantly affected by diseases associated with the hoof. Laminitis is a critical hoof disease that causes pain and, potentially, severe hoof and bone pathology. OBJECTIVE: To generate an equine hoof finite element (FE) model to investigate the impact of normal and toe-in hoof conformations on the degeneration (decrease in elastic modulus) of the laminar junction (LJ), as occurs in chronic laminitis. STUDY DESIGN: Computer software modelling. METHODS: A hoof FE model was generated to investigate the biomechanics of hoof laminitis. A 3D model, consisting of nine components, was constructed from computed tomography scans of an equine left forelimb hoof. The model was loaded with 100&#x2009;cycles of trotting. Two different centres of pressure (COP) paths representing normal and toe-in conformations were assigned to the model. LJ injury was modelled by degenerating the tissue's elastic modulus in the presence of excessive maximum principal stresses. RESULTS: FE models successfully showed findings similar to clinical observations, confirming third phalanx (P3) dorsal rotation, a symmetric distal displacement of the P3 (2&#x2009;mm at the lateral and medial sides) in the normal model, and an asymmetric distal displacement of the P3 (4&#x2009;mm at the lateral and 1.5&#x2009;mm at the medial side) in the toe-in model. The proximal distance between P3 and the ground after LJ degeneration in the current model was significantly different from experimental measurements from healthy hooves (P&#xa0;<&#x2009;0.01). MAIN LIMITATIONS: The inability to account for variations in population geometry and approximation of boundary conditions and system relations were the limitations of the current study. CONCLUSIONS: The distribution of LJ tissue degeneration was symmetric at the quarters in the normal hoof and in comparison, there was a lateral concentration of degeneration in the toe-in model.