Case description: A 2-year-old 5.1-kg (11.2-lb) castrated male Siberian cat was examined because of a history of an abnormal right pelvic limb gait and a 4- to 5-month history of progressive constipation. Radiographs obtained by the referring veterinarian showed an osteoproductive and osteolytic bony lesion that involved the right ischium and filled the obturator foramen.
Clinical findings: A hard mass was palpable in the right inguinal area, and rectal examination revealed a smooth bony mass on the ventral aspect of the right pelvic floor with marked reduction in the pelvic canal space. A 3.9 × 3 × 4.6-cm, mineralized mass bridging the right obturator foramen was present on CT images. The ventral component of the mass was slightly larger than its dorsal component, and lysis of the right pubic bone was present. There was no obvious soft tissue involvement.
Treatment and outcome: A limb salvage procedure involving internal hemipelvectomy with ipsilateral ischiectomy, contralateral partial ischiectomy, ipsilateral partial acetabulectomy, and femoral head and neck excision was performed. Histologic examination revealed that the mass was an osteochondroma. The cat recovered well and had good functional limb use immediately after surgery. The cat was still alive 1 year after surgery with good limb use.
Clinical relevance: Internal hemipelvectomy involving ischiectomy, partial acetabulectomy, and femoral head and neck excision can result in a good functional outcome in cats if the procedure is planned appropriately with a full understanding of the regional anatomy and adherence to surgical oncologic principles.
