Thoroughbred racehorses have been bred for speed to the point where their skeletal structure is increasingly unable to support their performance demands, leading to high injury rates.
Thoroughbred racing injuries including fatal breakdowns are partly a consequence of selective breeding that has not adequately considered skeletal robustness. The narrow genetic base of Thoroughbreds limits the diversity available for health-focused breeding. Racing surfaces including firm turf and synthetic tracks differ significantly in their injury rates. Young horses whose skeletons are still developing are entered in racing at two years old when training and racing loads cause cumulative bone stress. Pre-race diagnostic imaging programs using bone scan and thermography can identify high-risk horses and prevent racing until resolved. Veterinary pre-race inspections are mandatory in professional racing but vary in rigor between jurisdictions.