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carcinoma is often locally invasive but has a lower metastatic potential than oral melanoma. In dogs, aggressive surgical resection of the tumor can be curative if clean margins can be achieved (Figure 6). 6
Malignant oral melanoma is the most common malignant oral tumor found in dogs but is rarely diagnosed in cats. 1 These tumors are highly invasive and have a high metastatic potential, mostly to the regional lymph nodes and lungs. Wide surgical removal is the treatment of choice to obtain local control. Radiation therapy can be used in addition to surgery if clean margins are not achieved or as a primary mode of treatment if surgery is not an option. When combined with surgery or radiation therapy, a melanoma vaccine has been shown to increase the median survival time in some studies. Chemotherapy has not been shown to offer a significant survival benefit. 2 Cases in which the melanoma is identified and treated early, while the tumor is relatively small in size and prior to metastasis, can have a favorable prognosis (Figure 4). 3
Figure 5. Canine oral malignant melanoma attached to the buccal mucosa. This tumor was surgically resected with clean margins, but the dog eventually developed metastasis to the lungs 8 months after surgery. (Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS)
Figure 6. Very large and invasive mandibular squamous cell carcinoma on a dog that had been present for 9 months prior to surgical removal. The tumor was able to be completely removed with clean margins. The owners reported an increase in overall quality of life after tumor removal. (a: Pre op, b: Post op). (Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS) Similar to oral melanoma, if surgery is not an option or clean margins were not achieved, radiation therapy can be used to attempt local control. Chemotherapy has not been shown to be an effective treatment modality, but can be used for palliative care in dogs with SCC. 7 Prognosis is fair to good. Like dogs, aggressive surgical resection can be curative in cats. Unfortunately, it is often not an option as these tumors are typically too large and invasive at the time of diagnosis (Figure 7).
Figure 4. Canine oral malignant melanoma on the left mandibular gingiva that was able to be successfully treated with wide surgical removal of the tumor. (a: Pre op, b: Post op). (Photos courtesy of Dr. Michael Balke, DAVDC, F-OMFS) Unfortunately, melanomas that are not discovered until they are larger in size make local control more difficult and the chance of metastasis much higher, giving them a guarded to poor prognosis (Figure 5). Squamous cell carcinoma (SCC) is the second most common malignant oral tumor found in dogs 4 and the most common in cats 5 . There are various subtypes of oral squamous cell carcinomas, but broadly speaking, we will discuss tonsillar vs non tonsillar. Non tonsillar squamous cell
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