Effects of girth, saddle and weight on movements of the horse.

REASONS FOR PERFORMING STUDY Although the saddle is seen as one of the biggest causes of back pain, and weightbearing is seen as an important aetiological factor in 'kissing spine' syndrome (KSS), the effects of a saddle and weight on the back movements of the horse have never been studied. OBJECTIVE To determine the effects of pressure on the back, exerted by tack and weight, on movements of the horse. HYPOTHESIS Weight has an extending effect on the horse's back and, as a compensatory mechanism to this extension, an alteration in pro- and retraction angles was expected. A similar but smaller effect was expected from a saddle only and a lungeing girth. METHODS Data were captured during treadmill locomotion at walk, trot and canter under 4 conditions: unloaded; with lungeing girth; saddle only; and saddle with 75 kg of weight. Data were expressed as maximal extension, maximal flexion angles, range of motion of L3 and L5 and maximal pro- and retraction angles of the limbs. RESULTS At walk and trot, there was a significant influence on back kinematics in the 'saddle with weight' situation, but not in the other conditions. Overall extension of the back increased, but the range of movement remained the same. Limb kinematics changed in the sense that forelimb retraction increased. At canter, both the 'saddle with weight' and 'saddle only' conditions had a significant extending effect on the back, but there was no effect on limb kinematics. CONCLUSIONS AND POTENTIAL RELEVANCE Weight and a saddle induce an overall extension of the back. This may contribute to soft tissue injuries and the KSS. The data from this study may help in understanding the reaction of the equine back to the challenges imposed by man when using the animal for riding.