Vet360 Vet360 Vol 05 Issue 04 - Page 29

DENTISTRY Squamous cell carcinoma is the most common oral tumor in cats and carries a grave prognosis if located caudally or if it affects the base of the tongue. If located rostrally, surgery is the treatment of choice when clean, wide (at least 2-cm) margins can be obtained (Figure 3). As with squamous cell carcinoma, aggressive surgical excision that includes part of the dog's or cat’s mandible or maxilla is necessary. Radiation has been recommended to treat microscopic disease in fibrosarcoma tumors that are too large to obtain adequate margins. Hi-lo fibrosarcomas carry a poor prognosis regardless of surgery or radiation therapy. This may be partly due to the fact that most are associated with the maxilla and are thus more difficult to completely excise. Osteosarcoma. Although malignant, oral osteosarcoma, which usually occurs in the mandible of dogs, may not be as aggressive as osteosarcoma of the appendicular skeleton in the dog (Figure 5). Figure 3. Squamous cell carcinoma in a cat's rostral mandible. The NSAID meloxicam may have several beneficial effects in treating feline squamous cell carcinoma, including pain relief and reduced inflammation-associated neoplasia and oedema. In the United States, meloxicam is licensed only as a one-time injection for perioperative pain in cats. In Australia and Europe, low doses (0.01-0.03 mg/kg a day) have been used to treat osteoarthritis in cats without significant side effects. Fibrosarcoma. Diagnosed most commonly in the maxillae of large-breed dogs, fibrosarcoma is locally invasive but infrequently metastasises to the lungs (Figure 4). It is the second most common oral malignancy in cats (after squamous cell carcinoma). A subset of fibrosarcomas has been recognized in which the tumors appear histologically low-grade yet behave as high-grade malignancies biologically (hi-lo). Figure 5. Osteosarcoma affecting a dog's rostral mandible. Osteosarcoma is rare in cats In a study of 51 dogs with osteosarcoma treated with partial mandibulectomy alone (32 dogs); partial mandibulectomy and chemotherapy (10 dogs); partial mandibulectomy and radiation therapy (3 dogs); partial mandibulectomy, radiation therapy, and chemotherapy (4 dogs); and radiation therapy alone (2 dogs), the group treated with surgery alone achieved a 1-year survival rate of 71%, compared with the entire group’s 1-year survival rate of 60%. 5 In cases of maxillary osteosarcoma in both dogs and cats, recurrence is common after surgery. Chemotherapy and radiation in the treatment of oral osteosarcoma have not been associated with an increase in survival. Palliative radiation, single exposure every 2-3 months, very effective in controlling pain caused by inoperable maxillary osteosarcomas - Editor For a quick reference of all the oral tumors that can affect dogs and cats, see the sidebar, "Oral malignancy nomenclature," on page 27.. Figure 4. Fibrosarcoma affecting a dog's maxilla Issue 04 | AUGUST 2017 | 29