Equine Dorsal Metacarpal Disease Study Guide

Overview and Clinical Importance

Dorsal metacarpal disease (DMD), commonly known as bucked shins or sore shins, is the most common cause of lost training days in young Thoroughbred racehorses. This painful periostitis of the dorsal cortex of the third metacarpal bone (MC III or cannon bone) represents a critical topic for the NAVLE examination due to its high prevalence (affecting 66-70% of young Thoroughbreds in training) and significant economic impact on the racing industry, estimated at over $10 million annually in the United States alone.

DMD occurs exclusively in racehorses, primarily affecting the forelimbs of young horses (2-3 year-olds) entering speed training. Understanding the pathophysiology, diagnosis, treatment, and prevention strategies is essential for veterinarians working with performance horses.

Etiology and Pathophysiology

Bone Biomechanics

The third metacarpal bone experiences significant cyclic bending forces during high-speed exercise. During galloping, the dorsal cortex experiences compressive forces while the palmar cortex experiences tensile forces. The magnitude of these forces increases dramatically at racing speeds compared to slower gaits.