Nomenclature, classification, and documentation of catastrophic fractures and associated preexisting injuries in racehorses.

Racehorses are susceptible to bone fractures when damage from repetitive, high-magnitude loads incurred during training and racing exceed concurrent damage removal and replacement, resulting in transient periods of focal osteoporosis and bone weakening. Clinically, these events correspond to cortical stress fractures and subchondral bone stress remodeling. Evidence of these preexisting lesions include periosteal callus, endosteal callus, and intracortical focal hyperemia for cortical stress fractures; and subchondral focal hyperemia located superficial to sclerotic compacted trabecular bone tissue for subchondral stress remodeling. These findings must be in direct physical association with an acute fracture to infer that the abnormalities precipitated complete bone fracture. Recognition of preexisting lesions must be conveyed in the autopsy report to the racehorse industry audience because this is the mechanism for education of racehorse trainers, veterinarians, and owners. Standardized anatomic nomenclature, fracture classification, and documentation of gross autopsy findings specific to catastrophic bone fractures in racehorses provides information to empower changes in management of racehorses for the detection and management of mild injuries and prevention of catastrophic fractures.