Summary

The fetlock joint is the most common site of injury in Thoroughbred racehorses and a high proportion of fetlock injuries originate in the subchondral bone of the distal metacarpus. Our research group has identified two key factors that result in the accumulation of fatigue damage in the distal metacarpus which can progress to injury. First, galloping horses generate extreme loads within the distal metacarpal subchondral bone, and second, bone repair by remodelling at this site appears to be inhibited when horses are in race training. As remodelling is the primary means of replacement of damaged bone, an understanding of how remodelling is affected by race training and rest periods is essential to developing injury prevention strategies.
Metacarpal bones will be collected from horses that die or are euthanased on Victorian metropolitan racetracks that are in race training (n=25) and from racehorses that are resting at the time of death or euthanasia (n=25). Training history will be obtained from trainers and race records. Remodelling activity will be determined by examining metacarpal bones with backscattered electron microscopy, light microsocopy of undemineralised bone sections and, in suitable cases, fluorescence microscopy using oxytetracycline labelling, a drug which is widely used in the racing industry. Remodelling activity will be correlated with stage of training or rest period and comparisons made between training and non training horses.

The researcher has published the following journal article from this project was published: ‘Exercise-induced inhibition of remodelling is focally offset with fatigue fracture in racehorses’, Osteoporosis International: Volume 24, Issue 7 (2013), Page 2043-2048

Program

Thoroughbred Horses

Research Organisation

The University of Melbourne

Objective Summary

Determine how the subchondral bone of the distal metacarpus responds to training and rest.