Pathological analysis of bone fractures in race horses.

Pathomorphological analysis was performed on fractured bones of 470 race horses. The most common fracture site was the limb (98% of cases), and the majority of fractures were intra-articular. Focal osteochondral lesions consisting of osteochondrosis, osteonecrosis and osteosclerosis were observed frequently in fractured and non-fractured bones. In the fractured bones, the lesions frequently appeared in the vicinity of the fractured site. Under the influence of antecedent osteochondrosis from the young stage, osteosclerotic and osteonecrotic lesions may have been induced by immoderate exercise and localized ischemia. These morbid conditions may be important as local predisposing factors for bone fracture because the osteosclerotic and osteonecrotic lesions may contribute to diminished resistance to torsion and shearing forces.