Discussion

Introduction: Horses are increasingly trained on artificial surfaces, but a recent epidemiological study identified that arena characteristics affect risk of lameness in dressage horses, with arena maintenance being a potential protective factor. Aim: To investigate the effect of arena maintenance on arena mechanical properties and limb movement pattern at working trot on 2 different surfaces. Methods: Eight horses ridden by the same rider at 3.5 m/s on 2 surfaces: Surface 1 (S1); Waxed sand and rubber, harrowed and nonharrowed. Surface 2 (S2); Sand and fibre, watered and nonwatered. High speed motion capture (240
Hz) recorded 8 strides in a straight line. Forelimb and hindlimb hoof slide, fetlock angle and tarsal angle were determined. A dual-axis synthetic-hoof drop hammer measured mechanical properties at 10 arena locations. Data was analysed descriptively (mechanical properties) and comparatively (kinematic data). Results: S1: After harrowing there were decreases in maximum load (4.6%) and load rate (2.7%), increases in maximal vertical (3.8%) and horizontal acceleration (21%), indicating a softer surface with more grip. Hindlimb hoof slide, fore- and hindlimb fetlock angle at midstance, tarsal angle at stance onset and lift off were significantly greater post harrowing. S2: After watering there was increased maximum load (6.5%), load rate (1.7%), vertical (56.5%) and horizontal acceleration (38.9%) indicating a harder surface with more grip, while midstance tarsal flexion significantly increased (P<0.05). Conclusions and practical significance: Results suggest that arena maintenance alters surface mechanical properties and horses' locomotion pattern suggesting horses make proprioceptive gait modifications in response to surface alteration. These findings suggest that differences in surface components and/or maintenance techniques have an effect on the horse's proprioceptive response, highlighting the importance of training on different surface types to allow appropriate musculoskeletal adaptation and proprioceptive development. Acknowledgements: Funding: World Horse Welfare, Swedish-Norwegian Foundation for Equine Research, UK Sport for BEF World Class Programme.