Maintaining the equine skeleton in optimal condition is vital in order to ensure proper development of the young, growing horse, minimize risk of injury in the performance horse, and promote longevity and soundness throughout the horse's life.
Strength of bone is derived from a mineralized cartilage framework. Bone is a dynamic tissue and is therefore responsive to forces placed upon it. Bone also responds to changes in the amounts and ratios of calcium, phosphorus, and magnesium in the horse's diet. In addition, copper, zinc, manganese, vitamins A and D, and other nutrients have significant effects on bone development.
If the horse is fed a well-balanced and well-fortified diet, the largest single factor affecting bone strength is exercise. The remodeling of bone in response to exercise involves removing bone cells through the work of osteoclasts (cells that break down bone so that it can remodel and heal in response to stress and growth) and then building bone by osteoblasts (cells that make the cartilage matrix and are eventually mineralized).
Horses that do not receive free-choice exercise, such as those on stall rest or those managed in a stabled environment (show horses and racehorses), can be prone to demineralization of bone. This is especially common in young horses undergoing the transition from significant turnout to minimal or no turnout upon entering training.