Oral squamous cell carcinoma in a Vietnamese pot-bellied pig (Sus scrofa).

An 18-year-old, neutered, male Vietnamese pot-bellied pig (Sus scrofa) was treated for chronic, intermittent nasal discharge and sneezing. The animal was diagnosed with severe periodontal disease (grade IV), an oronasal fistula, and multiple tooth root abscesses via dental examination and computed tomography of the skull. Dentistry was performed, including multiple tooth extractions, and antibiotic therapy was initiated. Eighteen months later, the animal was evaluated for lethargy, anorexia, and a firm, 12 cm x 12 cm mass between the 2 rami of the mandible. Laboratory testing revealed moderate anemia, severe leukocytosis, and hyperglobulinemia. Skull radiographs indicated osteomyelitis of the mandible and soft-tissue swelling. A fine-needle aspirate and biopsy were taken, and results were consistent with squamous cell carcinoma. Treatment with piroxicam and antibiotics was initiated as needed to control signs of pain and secondary infection, respectively. Three months after diagnosis, the pig was euthanized due to cachexia and severe depression secondary to squamous cell carcinoma. On postmortem examination, the right mandibular area contained multiple, coalescing, irregular masses extending from the ramus rostrally to the mandibular canine teeth and ventrally within the intermandibular space, completely obliterating the normal anatomy. An open midshaft fracture was present on the right mandible. On histopathology, the masses were confirmed as locally invasive and destructive squamous cell carcinoma. No evidence of metastasis was noted in regional lymph nodes or in any of the distant sites evaluated.