Preliminary Evaluation of Toe-Heel and Mediolateral Hoof Balance at the Walk in Sound Horses With Toed-In Hoof Conformation

Empirically, toed-in hoof conformation has been associated with an increased risk of lameness and reduced longevity of equine athletes, presumably linked with changes in hoof balance. Therefore, toe-heel and mediolateral hoof balance of the vertical ground reaction force and limb-loading symmetry were objectively evaluated in five clinically sound, toed-in warmblood horses using a pressure plate. Five measurements of each forelimb were recorded at walk, and toe-heel and mediolateral hoof balance of the vertical ground reaction force were calculated throughout stance (126 Hz). Peak vertical force (PVF) and vertical impulse (VI) symmetry were calculated as lowest or highest mean value × 100%. All horses presented higher loading of the lateral zone at impact, rather equivalent loading of the medial and lateral zones at midstance, and increased lateral loading at the end of the stance phase in both forelimbs. Unexpectedly, left and right fore toe-heel balance in four of the five toed-in horses revealed higher loading of the toe zone at impact, whereas one horse presented higher loading of the heel zone at impact in both forelimbs. Limb-loading symmetry was 83.1 ± 8.7% and 84.1 ± 7.9% for PVF and VI, respectively, which was lower than expected in sound horses. It is unclear if the distinct difference in toe-heel balance compared with previously reported data in horses with normal distal limb conformation is actually predisposing to or is a consequence of pathology, but it may be associated with distal limb lameness, as increased loading of the toe early in the stance phase has been associated with navicular disease.