An 8-month old Maltese dog was referred because of a pathological fracture of the lateral portion of the right humeral condyle. A diagnosis of unicameral bone cyst was made based on radiographs, cytology/histology and long-term follow-up. Reduction and fixation, performed with a self-compressing pin, were preferred to amputation or arthrodesis. The dog did not experience any complications associated with the procedure. Functional recovery of the limb at the 1-year follow-up was considered excellent.