Easily the most crucial bone in a horse's anatomy the cannon bone is exposed to the greatest amount of stress when a horse is being worked hard. On a horse there isn't a very big support system around the cannon bone. The cannon bone is the large bone in the lower leg which runs from the knee down to the ankle. Its only support come from the tendons linking it to the knee and ankle bones and a covering of skin. There are no muscles linked to the cannon bone.
Hence it is crucial for the horse to have a well developed strong cannon bone to support its large frame during stressful workouts. 60% of its weight rests on the forelegs of a horse. We're talking about 60% of one thousand to twelve hundred pounds. A horse going at a full gallop or doing lightning quick turns is exerting a tremendous amount of force on what is about the size of a large stick.
The reason that large stick doesn't automatically snap right off every time the horse takes off is the extraordinary way the leg is designed to be a shock absorber. From the shock absorbing cushion of the sole in the hoof along the impact absorbing tendons to the upper leg muscles the blow of striking the ground with such force is redistributed and absorbed.
Even so many horses suffer life threatening injuries to the keystone bone known as the cannon bone. One such example was the famous and well loved race horse who recently succumbed to complications from his cannon bone fractures. More common are the front cannon fractures but there are also hind cannon fractures often caused by a hard bump, a kick from another horse or a bad misstep.
Reseach is always ongoing on how to prevent this tragic and often fatal injury. Key elements are selective breeding for better bone structure and improvements in running surfaces for greater protection. Also important are proper training and conditioning methods which allow for the leg to mature and become strong. Like any athlete the horse must be brought along slowly and carefully to reach his full potential.
Some disciplines use protective devices such as splint boots and running bandages to further shield the horse's cannon bone from the risk of injury. These can be helpful but if not used correctly can actually cause harm. improperly adjusted gear if too tight can cause circulation problems in the legs or bowing of the tendons and if too loose can cause chafing or skinburns in addition to not providing the proper support.
We continue to learn how to save our equine companions from harm. I for one hope for new research which will greatly lessen the risk of cannon bone injury and for more great strides in veterinary medicine to better treat fractures of the all important cannon bone.