A three-year-old Warmblood filly presented with left forelimb lameness of two weeks duration with a discharging sinus over the lateral aspect of the mid-metacarpal region. The filly was diagnosed with a proximal, open, comminuted fracture of metacarpal IV (MCIV). Initial treatment with local debridement and systemic antimicrobial administration was unsuccessful, with the development of osteomyelitis which cultured a methicillin resistant Staphylococcus pseudointermedius. A subsequent segmental ostectomy was performed resulting in avulsion of proximal MCIV from metacarpal III post-operatively. Reduction and internal fixation of the displaced MCIV with cortical lag screws was performed, with immediate bone failure during recovery from general anaesthesia. The proximal MCIV was then removed under standing sedation and local anaesthesia. Subsequent development of osteoarthritis in the carpometacarpal and middle carpal joints was likely secondary to joint instability, but the horse was sound 12 months post-operatively. Despite the surgical complications in this case being previously described, there are no reports on the removal of metacarpal splint bones in the horse to the author’s knowledge. As the prognosis for this case is considered good for future athletic performance, proximal or complete MCIV resection could be considered as a possible treatment option in select cases.