Effect of horseshoe design on lateral-medial heel movement in equine hooves compared to barefoot conditions

<b>Background: </b>Hoof-heel movement is important for proprioception and load distribution. This mechanism helps to lower the peak loads on the distal limb and reduces the risk of overload injuries. Previous studies have indicated that steel horseshoes restrict heel expansion. <b>Objectives: </b>To compare lateral-medial heel movement between barefoot hooves and hooves fitted with five different types of conventional horseshoes at three levels of the hoof during the walk and trot. <b>Study Design: </b>Randomised in vivo study. <b>Method: </b>Nine warmblood horses were walked and trotted in a straight line on an asphalt surface through a high-speed camera array, both barefoot and shod with five different types of horseshoes. Using glued reflectors, kinematic data were collected from three levels of the hoof: the hoof cartilage, coronary band, and distal hoof wall. Heel movements were then analysed and compared. <b>Results: </b>At the level of the coronary band, in both the walk and trot, barefoot hooves exhibited significantly greater heel expansion and contraction than hooves shod without a bar. At the distal level of the hoof wall, no significant differences were observed in heel expansion among the different shoes, or between the shod and barefoot conditions. In trot, hooves fitted with 8 mm standard and short- and long-sloped shoes demonstrated significantly less heel constriction than barefoot hooves. <b>Main Limitations: </b>The primary limitations were the small sample size of horses and the inability to measure heel movement across all gaits and on surfaces more commonly used for riding. <b>Conclusions: </b>With the exception of the coronary band level, steel horseshoes do not significantly restrict heel expansion compared to barefoot conditions. In contrast, heel expansion increased at the level of the hoof cartilage when a 10 mm standard steel shoe or a heartbar shoe was used. Ultimately, being shod with steel shoes primarily restricts heel constriction at breakover.