Born to run? Racing and training outcomes, population dynamics and traceability of a Thoroughbred birth cohort

Analyses of industry-level data suggest that around one-third of the UK and Ireland Thoroughbred foal crop fail to enter training. Prospective follow-up of individual horses could provide additional insight, particularly around individuals not attaining specific career milestones.

A Thoroughbred birth cohort was established on stud farms across the UK and Ireland. Training, race performance, sales, export data, destinations and reasons for individuals failing to meet career milestones were collected from stud records, follow-up with owners, stud book and racing authorities' databases, and publicly available data sources to the end of the fourth year of life.

Of 262 foals that were alive at the end of the second year of life, 94.7% (248/262; 95% confidence interval [CI] 91.2‒96.8) were registered with a licensed trainer and 79.0% (207/262; 95% CI 73.7‒83.5) had raced at least once by the end of the follow-up period. Just eight individuals, all of which had been sold as foals and/or yearlings, had an unknown fate or whereabouts.

Outcomes for horses exported out of the UK may be underestimated.

Wastage may be lower than industry-level figures suggest, highlighting important traceability gaps at this level, likely due to the dynamic nature of Thoroughbred populations.