Neoplastic mass involving the zygomatic arch in a sheep: clinical, sonographic, radiographic, pathological, and CT findings

Abstract

A five-year-old intact female East Friesian sheep was presented for examination, following a noted decrease in feed intake and general apathy. A swelling was observed under the right eye. Ultrasonographic examination exposed a mass with a highly irregular texture and distinct loss of the normal bone surface echogenicity of the zygomatic and temporal processes. An ultrasound-guided fine-needle aspirate was performed which showed that the mass was a malignant spindle-cell sarcoma. The sheep was euthanased and a postmortem CT examination revealed extensive damage to the tissues surrounding the mass. Immunohistochemical staining helped to confirm the diagnosis fibrosarcoma. This case shows the value of using ultrasonography in working up such cases in general practice. The technology is available to most farm animal veterinarians and, in the authors’ opinion, should be used more extensively in practice.