Estimates of genetic parameters of distal limb fracture and superficial digital flexor tendon injury in UK Thoroughbred racehorses.

Authors: Welsh Claire E, Lewis Thomas W, Blott Sarah C, Mellor Dominic J, Stirk Anthony J, Parkin Timothy D H

Journal: Veterinary journal (London, England : 1997)

DOI: 10.1016/j.tvjl.2014.03.005 PubMed: 24679457Log in to save

Summary

# Editorial Summary: Genetic Factors in Thoroughbred Racehorse Limb Injury Welsh and colleagues analysed over 66,000 UK Thoroughbred racing records to establish the heritable components of two career-threatening conditions: distal limb fracture and superficial digital flexor tendon (SDFT) injury. Using genetic modelling on British Horseracing Authority data spanning a decade, they found moderate to substantial heritability estimates—distal limb fracture ranging from 0.21 to 0.37 and SDFT injury from 0.31 to 0.34—with notably higher heritability for SDFT injury in flat racing (0.34) than jump racing (0.31). Importantly, a positive genetic correlation between the two conditions suggests shared underlying hereditary factors predispose individuals to both injuries, meaning selection pressure against one may inadvertently reduce risk of the other. These findings carry significant implications for stud selection and breeding programmes, as the demonstrated heritability indicates meaningful scope for reducing injury incidence through targeted genetic selection, though the moderate effect sizes also underscore that environmental and management factors remain critical to injury prevention strategies.

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Practical Takeaways

•Distal limb fracture and SDFT injury have moderate-to-substantial heritable components, making selective breeding a viable strategy to reduce incidence in racing populations
•The positive genetic correlation between these conditions means selecting against one may inadvertently reduce risk of the other, simplifying breeding program objectives
•Stud farms and racing organizations can use these heritability estimates to prioritize sires and mares in breeding decisions to improve limb soundness

Key Findings

•Heritability of distal limb fracture ranged from 0.21 to 0.37 across racing populations
•Heritability of SDFT injury ranged from 0.31 to 0.34 across racing populations
•SDFT injury and distal limb fracture were positively genetically correlated
•Genetic parameters suggest breeding strategies could reduce risk of both conditions

Conditions Studied

distal limb fracturesuperficial digital flexor tendon injury

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