A 5-year-old Australian Stock Horse gelding was initially referred to the Charles Sturt University Veterinary Clinical Centre (CSUVCC) for assessment of a penetrating laceration over the medial splint bone (second metacarpal bone) of the left foreleg. Clinical examination failed to reveal a communication with a synovial structure, but radiographs showed a palisading bone reaction on the proximal aspect of the medial splint bone which was thought to be a characteristic of infection. Soft tissue swelling precluded access to a peripheral vein, so a decision was made to use intraosseous regional limb perfusion. This was achieved through an access portal in the lateral diaphysis of the third metacarpal bone (McIII). Subsequently, the horse developed lameness and further investigation revealed a nondisplaced longitudinal fracture of McIII propagating from the intraosseous regional perfusion access portal.