Summary Reasons for performing study: Collapsed heels conformation has been implicated as causing radical biomechanical alterations, predisposing horses to navicular disease. However, the correlation between hoof conformation and the forces exerted on the navicular bone has not been documented. Hypothesis: The angle of the distal phalanx in relation to the ground is correlated to the degree of heel collapse and foot conformation is correlated to the compressive force exerted by the deep digital flexor tendon on the navicular bone. Methods: Thirty‐one shod Irish Draught‐cross type horses in routine work and farriery care were trotted over a forceplate, with 3‐dimensional (3D) motion analysis system. A lateromedial radiograph of the right fore foot was obtained for each horse, and various measurements taken. Correlation coefficients were determined between hoof conformation measurements and between each of these and the force parameters at the beginning (15%) of stance phase, the middle of stance (50%) and at the beginning of breakover (86% of stance phase). Significance was defined as P<0.05. Results: The force exerted on the navicular bone was negatively correlated (P<0.05) to the angle of the distal phalanx to the ground and to the ratio between heel and toe height. This was attributed to a smaller extending moment at the distal interphalangeal joint. There was not a significant correlation between the angle of the distal phalanx and the degree of heel collapse, and heel collapse was not significantly correlated to any of the force parameters. Conclusions: Hoof conformation has a marked correlation to the forces applied to the equine foot. Heel collapse, as defined by the change in heel angle in relation to toe angle, appears to be an inaccurate parameter. The forces applied on the foot are well correlated to the changes in the ratio of heel to toe heights and the angles of the distal phalanx. Potential relevance: Assessment of hoof conformation should be judged based on these parameters, as they may have clinical significance, whereas parallelism of the heel and toe is of less importance.

Contrast radiography performed at the same time as intrathecal analgesia provides useful information regarding the presence of MF tears and DDFT tears, which can assist in the decision of whether to manage the lameness conservatively or with tenoscopic evaluation.

A mobile system that reliably detects and quantifies hindlimb lameness in horses during unconstrained locomotion could be a valuable tool to perform an evidence-based assessment of lameness in horses in a clinical setting, e.g. before and after nerve blocks or before and after surgery.

Summary A variety of horseshoe designs are believed to ‘ease’ breakover, or the unloading of the foot once the heels leave the ground. In this study, conventional toe‐clip shoes, quarter‐clip shoes, fitted to the white line at the toe, and Natural Balance horseshoes were fitted to the front feet of 9 sound Irish Draught‐cross type horses. Forceplate and video motion analyses were undertaken during trot locomotion to determine the moment arm of the ground reaction force on the distal interphalangeal (DIP) joint, the peak DIP joint moment and the peak compressive force on the navicular bone. DIP joint moment arm during breakover was reduced with both Natural Balance (mean ± s.d. 77 ± 7 mm) and quarter‐clip shoes (78 ± 9 mm) compared to the toe‐clip shoes (86 ± 6 mm) (P<0.01). Peak DIP joint moment was not significantly different (175 ± 37, 171 ± 38 and 175 ± 31 Nmm/kg, in Natural Balance, quarter‐clip and toe‐clip shoes, respectively) and neither was peak force on the navicular bone (5.52 ± 1.52, 5.79 ± 1.53 and 6.14 ± 1.47 N/kg, respectively). Breakover duration (heel off to toe off) was not significantly reduced by the Natural Balance shoes (39 ± 6 ms) or the quarter‐clip shoes (40 ± 6 ms) compared to toe‐clip shoes (42 ± 9 ms). This study has demonstrated that the use of Natural Balance shoes reduces the moment arm of the ground reaction force (GRF) during breakover but does not reduce the peak DIP joint moment or the force on the navicular bone.