Suspensory ligament injuries are relatively common in dressage horses, but there is little scientific information available on their causes. A recent study by researchers at the Animal Health Trust in Newmarket, England, examined the possible link between movement patterns at the collected and extended trot, and risk for suspensory ligament injuries.

Scientists used a high-speed camera to capture four Warmbloods working in collected and extended trot on three different surfaces. Each horse wore brushing boots fitted with inertial motion sensors and markers at five points on the hind legs to aid in video analysis.

The results demonstrated that when horses performed the collected trot across all three surfaces tested, there was a decrease in speed and stride length (measured in meters) but an increase in stride duration (measured in seconds) compared to extended trot.

Conversely, in the extended trot, horses showed an increase in flexion of the hock and extension of the fetlock when the limb was in contact with the ground. This suggests that there might be more strain placed on the suspensory ligament at extended trot compared to the collected trot, the team relayed. The authors suggested that this could be because the horse is moving over a greater distance at a greater speed at extended trot, increasing relative protraction and retraction of the hind limb, putting more strain on the soft tissue structures of the leg