Effects of sand, asphalt, and a three degrees hind toe or heel elevation on equine cervical and thoracolumbosacral kinematics at walk and trot.

Background: Effects of ground surface and hoof angles on equine cervical and thoracolumbosacral kinematics are poorly understood. However, the equine cervical and thoracolumbosacral areas present frequent lesions and he management of factors that might improve treatment and rehabilitation outcomes, such as ground surface and hoof angles, requires more investigation.

Aims: Our objectives were to determine the influence of ground surface (asphalt versus sand) and a 3 degrees hind toe or heel elevation on cervical and thoracolumbosacral kinematics during walking and trotting.

Methods: Six saddle horses were equipped with reflective markers and shod with reference shoes (REF), consisting of fore aluminium (REF F) and hind steel racehorse (REF H) shoes. Two-dimensional videos, performed with a camera placed perpendicularly to the horse, were used to compare kinematic parameters when walking and trotting in hand on asphalt and sand. On asphalt, REF was also compared with REF F and a modified REF H using additional three degrees hind toe or heel wedges.

Results: During walking or trotting, horses showed increased mid-cervical flexion (2±0.8°), cervicothoracic extension (5±1.5°) and thoracolumbar flexion (2.3±0.8°), and a reduction in lumbosacral range of motion (3±0.8°) on asphalt versus sand. Hind heel or toe elevation increased both adaptative cervicothoracic flexion (5±1.6°) and lumbosacral extension (3±0.9°) at walk, relative to REF. An increased plantar hoof angle induced more lumbosacral extension (3±1.3°) at walk. At trot, toe elevation reduced thoracothoracic flexion (2.7±1.1°) and heel elevation reduced thoracothoracic extension (2.9±1.1°).

Conclusion: These observations could be useful for clinical, rehabilitation, training, and performance assessments.