Strong bones are essential if a horse is to perform successfully and still remain sound. Bones that are weakened by disease, injury, or inappropriate training regimens can result in catastrophic injury, as anyone involved with racing well knows. There are a number of elements involved in the production of strong bones. The two prime elements are proper nutrition and the correct kind of exercise. We will focus in this article on the role played by exercise.

The equine world is indebted to David Nunamaker, VMD, PhD, an orthopedic surgeon and head of the University of Pennsylvania’s New Bolton Center, for information on the role exercise plays in the formation of bone. Aided by grants from the United States Department of Agriculture, the New York Chapter of the Horsemen’s Benevolent and Protective Association, Grayson-Jockey Club Research Foundation, and the National Institute of Health, Nunamaker and his associates carried out in-depth research on bone development beginning in the late 1980s and continuing to the present that provided a great deal of information about the role played by exercise. Heavily involved in the early research with Nunamaker were Bill Moyer, DVM, formerly at New Bolton and today head of the Large Animal Medicine and Surgery Department at Texas A&M University, and John Fisher, DVM, a horse training veterinarian from Maryland, who was the first to try Nunamaker’s suggested approach for building strong bones in young racehorses.

The focus of their research involved bucked shins, but what they learned also provided enlightening information about exercise-induced development of bone.

The condition of bucked shins was and, continues to be, a costly and time-consuming problem in Thoroughbred racehorses. Estimates varied when Nunamaker’s research began, but it was believed that somewhere between 65-90% of all Thoroughbreds in the United States bucked their shins in early training. Why did this happen? the researchers wondered