Everyone involved in the racing industry knows that one of the major problems in training horses is keeping them free from injury. Bones, joints, tendons, and ligaments are placed under considerable strain during training and racing, and it seems inevitable that, at one time or another, all horses will suffer some kind of musculoskeletal injury. "Wastage" is a term used in the industry to describe losses that occur during the training and racing of a horse. These losses can be measured in terms of days out of training and lost racing opportunities, as well as the financial losses that stem from these interruptions to a horse’s training program (e.g., veterinary care and reduced income from race winnings). In a worst-case scenario, the horse must be retired from racing.

A number of studies have shown that musculoskeletal injury is by far the most common reason for wastage. In fact, the statistics are staggering — for example, a study of 314 Thoroughbreds in Newmarket, England, found that lameness was the single most important reason for wastage in young horses in training. More than half of those horses experienced a period of lameness, and in about 20% of affected horses, lameness was severe enough to prevent racing during the period of investigation.

Although it is recognized that many different factors can contribute to the development of musculoskeletal injury, in Thoroughbred circles it has been suggested that many of these problems stem from the training and racing of 2-year-olds. Most racehorses begin training at 18 to 20 months of age, a year or more before the skeleton has reached full maturity. Potentially, intensive training at that young age might predispose the horses to career-limiting injuries.