Comparison of Heel Movement Between two Different Glue-on Type Shoes and Nailed Shoes in Thoroughbreds

Gluing an aluminum shoe onto equine hooves has been known to restrict heel movement and might cause interference with shock absorption and blood flow to the hoof. To investigate the effects of new glue-on type shoes on heel movement, 2 experiments that compared forelimb heel movement between conventional nailed shoes and flexible polyurethane glue-on shoes or Hanton-type shoes, which had 2 side clips for adhesive, were conducted on separate days. A displacement sensor was fixed on the heel to measure the forelimb's mediolateral heel movement. Exercise consisted of walking at 1.7 m/s, trotting at 4 m/s, cantering at 8 and 12 m/s for 30 seconds on a treadmill without a slope. The average heel expansion, contraction, and total heel movement (sum of the absolute expansion and contraction values) of 10 consecutive strides between the nailed shoes and glue-on shoes were compared using the paired t-tests. No significant differences in heel movement were observed between polyurethane glued shoes and nailed shoes regardless of gait. During trotting, Hanton shoes promoted significantly smaller heel expansion (14% decrease, P < 0.01) and larger heel contraction (11% increase, P = 0.03) compared to conventional nailed shoes, although no difference in total heel movement was observed. Furthermore, neither heel expansion nor contraction nor total movement in other gaits showed significant differences between Hanton shoes and conventional nailed shoes. The aforementioned results suggested that the new glue-on type shoes promoted similar heel movement compared to conventional nailed shoes.