48 - Veterinary aspects of training Thoroughbred racehorses

Thoroughbred racing evolved in England over 200 years ago and now exists in over 50 countries. A comparison of the size of Thoroughbred flat racing industries between some of the major racing countries based on foal crop, number of races and starters, prize money and betting turnover is illustrated in Table 48.1. All facets of the Thoroughbred racing industry rely heavily on veterinary input, which extends from pre-conception to the end of a horses’ athletic career. Termination of a racing career may result from veterinary advice pertaining to injury or disease, or be based on economic grounds and an assessment of athletic ability. Horses are typically retired to stud if they have accomplished a superior racing career that they are unlikely to better, or have genetic potential that would offset their future potential race earnings. Alternatively, other horses are routed to other athletic endeavors if they are functionally sound. Horses have their first opportunity to race as 2 year olds and their competitive longevity is the result of a multitude of veterinary and specific industry-based factors. Generally the majority of the racing population is made up of horses aged 2 through 5 years of age. Sex distribution of the racing population commences with relatively equal proportions of males and females as yearlings and 2 year olds. In subsequent racing years there is an attrition of females to breeding so that horses older than 4 years of age, are typically gelded males (Fig. 48.1 and Fig. 48.2). Age of first race start depends on athletic conformation, degree of maturity, genetics, aspirations and expectations of the owner and trainer, as well as race programming and prize money structure of the specific country. Attempts to judge musculoskeletal maturity and suitability for racing based on objective means such as physeal closure have been generally unsuccessful. The actual time of first race start is then dependent on the response to training, health, and soundness. Interestingly, in a study examining factors affecting early career wastage there was no correlation between sex and foaling date with time of first race start. While concerns over racing 2-year-old horses exist, two studies CHAPTER CONTENTS