Toe modifications in hind feet shoes optimise hoof-unrollment in sound Warmblood horses at trot.

REASONS FOR PERFORMING STUDY: It was shown that rolled-toe shoes smooth hoof-unrollment and thereby reduce peak loading of forelimbs in trotting Warmblood horses. Shoe design and shoeing technique for hind feet have been modified over recent decades from fully fitted, toe-clipped shoes to set-back, side-clipped shoes. OBJECTIVES: To study the effects of different shoe modifications on loading and movement of the hind hoof. METHODS: Ten clinically sound Warmblood horses were shod with 3 types of hind shoe: first, fully fitted, toe-clipped shoes, followed randomly by side-clipped shoes without a rolled toe that were set back by half the thickness of the hoof wall in the plantar direction and identical side-clipped shoes with a rolled toe, with 2 days between shoeing sessions to adapt to the shoes. Then horses were trotted in a straight line over a pressure-force plate combination. Hoof dynamics were compared statistically with the fully fitted shoe condition using a general linear model repeated measures test (P<0.05). RESULTS: There were no significant differences in the characteristics of limb timing, such as stance time and breakover duration nor the peak vertical and horizontal ground reaction force. By setting back the hind shoes, the centre of pressure at toe-off was positioned less dorsally. The rolled toe resulted in a smoother shift of the centre of pressure and thus more fluent hoof-unrollment. Both alternative types of shoe allowed a more lateral orientation of the centre of pressure at toe-off. CONCLUSIONS AND POTENTIAL RELEVANCE: Toe modifications of hind shoes can influence hindlimb kinematics positively. Setting the hind shoe back and rolling the toe leads to smoother hoof-unrollment, which enables the horse to coordinate movement correctly without loss of propulsion. Thus, shoe modifications might facilitate movement and thereby help prevent overload injuries.