Management strategies to prevent future injury in the Thoroughbred

Introduction

Over 80% of catastrophic injuries at Thoroughbred racetracks are the result of fractures. The prevalence of such incidents varies greatly between racing jurisdictions and race types, but typically ranges between 6.6 cases/1000 starters in jump races and 0.9/1000 starters in flat racing. The loss of these horses is a significant ongoing issue for the industry, both financially and in terms of human and equine welfare. The majority of catastrophic fractures are the consequence of fatigue. Through an understanding of the processes involved in fatigue damage of bone, it should be possible to implement strategies to reduce the accumulation of fatigue damage and to facilitate its repair. In addition, the progressive nature of fatigue damage means that, if we can identify the injuries early enough, we can intervene while the damage is still reversible. Achieving these objectives will require the following strategies:

1. Eliminate the cause

Fatigue is a consequence of cyclical loading. Fatigue life is exponentially related to the magnitude of deformation (strain) from each cycle of load. Strain will depend on the stress applied, which, in turn, will depend on the magnitude and direction of load and the mass and architecture of the bone. The number of cycles of load and the magnitude and direction of load are dependent upon the training schedule (peak load is proportional to speed and principal strain direction varies with speed). Conversely, the geometric properties of bone are refined by the physiological process referred to as ‘adaptation’.  […]