What makes a successful racehorse? Is it genetics, upbringing, training — or something more subtle? A new study conducted by researchers in the UK, Canada and the USA and published in the Equine Veterinary Journal provides fresh insight into how a Thoroughbred’s early life may influence its destiny on the racetrack.
Researchers followed 129 Thoroughbred foals on six breeding farms in the UK from birth to their early racing years to investigate how their management and health affected whether they ended up racing — and how well they performed if they do make it to the starting gate. The team looked at gestational information, early life turnout, and age at weaning, among other factors. Then they tracked these horses through their racing careers up to the end of their four-year-old season, focusing on three main outcomes:
- Likelihood of racing
- Total number of starts
- Total prize money earned by the end of their three-year-old season
Of the 129 foals in the study, 76% (98) ultimately raced, with a median of seven starts and £6898 ($12,850 CAD) in median earnings. The researchers found that:
1. Time Outdoors Matters
Foals that spent more hours outside in their first six months of life were more likely to start a racing career. The predicted probability of racing was around 24% for foals that were turned out an average of 8 hours or less during the day and in at night for the whole 6-month period, and around 70% for those who spent the first months of life in at night and out during the day, with turnout times gradually increasing to 24/7 for the remaining months.
Additionally, those that had access to larger turnout pastures tended to earn more prize money over their careers. Simply put, greater space and freedom in early life was linked to better performance outcomes later on. This makes sense biologically, as early movement can help strengthen bones, joints and muscles, while allowing young horses to build balance, coordination and social skills.
2. Weaning
The study found that foals weaned at a slightly older age were more likely to actually begin their racing careers, and have longer, more active racing careers. This varied from just over 40% for individuals weaned at 4 months of age to almost 90% for those weaned at 8 months of age.
It is known that early weaning can be stressful and may disrupt physical and emotional development. Allowing foals a longer period with their dam may help support healthier growth and adaptability.
3. Influence of the Mare
Previous studies have found that overnutrition, obesity, and concentrate feeding during pregnancy in mares can impair glucose metabolism in their offspring up to 18 months and increase the risk of osteochondrosis. Likewise, in-utero growth restriction and shorter gestation disrupt offspring metabolism and raise the risk of developmental orthopedic disease, potentially affecting athletic performance. Older mares may restrict fetal growth due to reduced uterine blood flow and placental perfusion, which may explain why their progeny show reduced racing performance compared with those from younger dams.
Conclusions
While the study looked at many factors, actual training data wasn’t included — such as how much race training the horses received after leaving the farm — because those records weren’t readily available. Also, some early life measures had low statistical power, meaning the sample size wasn’t large enough to detect effects for every variable the researchers examined. The study doesn’t claim that early life environment determines success as a racehorse; there will always be individual differences in ability, temperament, and even luck. But it suggests a real link between early environmental experiences and later athletic potential.
For breeders and managers, practical takeaways include:
- Prioritizing larger turnout areas for foals so they can move and develop freely
- Allowing more natural socialization and physical development in the first six months of life
- Reevaluating weaning practices to balance health, stress and long-term athletic potential
Understanding how early life influences racing outcomes can help breeders and trainers create environments that support healthier development — potentially leading to better performance and improved welfare.
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