Why do horses suffer tendon injuries so frequently?
This is a question often asked by anyone who takes part in high speed horse sports such as racing, team chasing or eventing!
The answer is that the equine lower limb is a marvel of engineering which has adapted its anatomical and physiological features to allow the horse to cover large distances at slow speeds (while grazing) while retaining the ability to use speed when necessary to escape predators.
To do this the limb has evolved to reduce the metabolic cost of locomotion, so the horse can move constantly using minimal muscular activity, therefore reducing the likelihood of fatigue.
However the adaptations which make the limb fast and lightweight also make them more vulnerable to injury.
At gallop each limb is placed under extreme load, approximately 2.5x the horse’s bodyweight (around 1500kg in a 500g horse) which, considering how small the cross-sectional area of the limb is, makes it no surprise that tendon injuries are common in horses that gallop!