Fracture rate in Thoroughbred racehorses is affected by dam age and parity.
Authors: Verheyen Kristien L P, Price Joanna S, Wood James L N
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Maternal factors exert a measurable influence on fracture susceptibility in Thoroughbred racehorses, with both dam age and parity significantly affecting the injury risk of offspring during training. Researchers tracked 335 yearlings entering flat racing training under eight different trainers across a two-year period, using multivariable Poisson regression to analyse fracture incidence relative to maternal characteristics. Contrary to initial hypotheses, first foals demonstrated substantially lower fracture rates than subsequent offspring (relative risk 0.33), whilst fracture risk decreased by approximately 9% for each year increase in dam age. These findings suggest that skeletal robustness in young racehorses is shaped by intrauterine developmental conditions influenced by maternal parity and age, rather than by simple generalised "older mare weakness" or first foal vulnerability. For breeding programmes and those managing young stock, this data indicates that mares in their middle reproductive years produce offspring with potentially superior skeletal resilience, warranting further investigation into the specific physiological mechanisms—nutritional, hormonal, or biomechanical—that link maternal characteristics to fracture resistance during the demanding transition to race training.
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Practical Takeaways
- •Expect higher fracture risk in horses from multiparous mares; consider additional conditioning or monitoring for these individuals
- •Younger dams (particularly first-time mothers) produce offspring with lower fracture rates, suggesting maternal age and experience affect fetal skeletal development
- •Fracture risk assessment in young racehorses should account for dam age and reproductive history as part of predisposing factor evaluation
Key Findings
- •First foals had significantly lower fracture rates than subsequent foals (RR=0.33, P=0.02)
- •Fracture rate decreased by 9% per year increase in dam age (RR=0.91, P=0.03)
- •Dam age and parity influence skeletal development and injury risk in offspring during racing training
- •Study provides first evidence that prenatal and perinatal maternal factors affect equine fracture susceptibility in later life