Thoroughbred Geldings' Career: Influence of Age at the Start of Training and Racing.

This retrospective report investigated whether starting racehorses' training and racing early is associated with a less successful and a shorter racing career. The data of 600 Thoroughbred racehorses from the German Racehorse Association's archiving programme were evaluated. The horses were classified into three groups regarding their different ages when starting training and racing: early training (16-24 months old)/early racing (two years old); early training/late racing (>two years old); and late training (25-30 months). Statistical models investigated effects on the horses' length of career. The results showed that the length of their racing career was influenced by sex; geldings showed the longest career as they do not enter breeding programmes, and were analyzed separately. Geldings entering training early, with their first race at two years old, showed higher ratings and a similar length of racing career than those with their first race at three years old or more. Thus, early racing appeared to have had no negative effect on the length of the racing career or perseverance in racing in the geldings investigated. Further studies researching training effects and physiological resilience should consider alternative explanations for racing selection criteria (e.g., early maturation advantage and prior unsoundness) and the reason for ending a racing career.