Atypical Presentation of Retained Cartilage Cores with Femoral Physeal Fracture in a Young Flat-Coated Retriever Dog.

A 9-month-old male entire flat-coated retriever was referred for investigation of chronic right pelvic limb lameness following trauma. Radiographs and contrast-enhanced CT confirmed a right femoral head Salter-Harris type III fracture with monostotic metaphyseal mixed-type lysis and joint effusion. An aggressive process due to underlying neoplasia or infection with secondary pathological fracture could not be excluded. The dog underwent surgical bone biopsy and, consequently, right femoral head and neck ostectomy (FHO). Histopathology described retained cartilage cores within the trabecular bone of the metaphysis and periosteal resorption in the right femoral head and neck, with no signs of inflammation or malignancy.