Concurrent Acute Fracture and Dysplasia-Related Fragmentation of the Medial Coronoid Process of the Ulna in a Dog-A Case Report.

A 4-year-old neutered male Labrador retriever presented with acute-onset nonweight-bearing lameness of the right forelimb following play activity. Physical examination revealed crepitus and pain on elbow flexion. Radiographic examination showed a linear lucency at the cranial margin of the medial coronoid process of the ulna (MCP), with sclerosis and periosteal new bone formation, consistent with degenerative joint disease secondary to elbow dysplasia (ED). Computed tomography (CT) identified two distinct fragments adjacent to the MCP. Arthroscopic partial coronoidectomy was performed with successful retrieval of both fragments. On histopathological examination, one fragment demonstrated chronic changes, consistent with dysplasia-related FMCP, whereas the other exhibited features consistent with acute trauma/fracture. The patient recovered well at 6-week postoperative evaluation. This is the first reported case of concurrent developmental FMCP and traumatic MCP fracture in the same limb in a canine patient, confirmed via multimodal imaging and histopathology. This report highlights the diagnostic role of CT imaging and histopathology in differentiating overlapping pathologies and raises the question whether underlying ED plays a role in secondary traumatic injuries in dogs.