Clinical Aspects of Subchondral Bone Pain in the Fetlock in Racehorses and Sport Horses

For the purposes of this abstract the subchondral bone refers not only to the subchondral bone plate, but also the underlying trabecular bone. Although there are some overlaps between the injuries seen in flat racehorses and sports horses, their clinical presentations are often different and are therefore considered separately.

Flat racehorses

Subchondral bone pain is often the result of a stress-adaptation mismatch injury involving the condyles of the third metacarpal/metatarsal bones, frequently involving both forelimbs or both hindlimbs, or all 4 limbs. Therefore the presenting complaint is usually loss of action or decline in performance, rather than overt lameness. The horse may have a short scratchy trot and prefer to canter than to trot. However, if the hindlimbs are involved the canter may lack hindlimb impulsion, the horse tending to bunny hop behind. However, less commonly the horse may present with an overt unilateral lameness, but following diagnostic analgesia contralateral limb lameness may become apparent. Increased mineralisation of the trabecular bone may predispose to fracture resulting in acute-onset, severe lameness, but frequently poor action preceded this. […]