ORAL TUMORS
Oral tumors represent 6% of all neoplasms in the dog and are the fourth most common neoplasm in dogs. Cancer of the mouth and pharynx occurs more frequently in dogs than in cats.
Male dogs may be at greater risk for developing an oral tumor than female dogs. Most oral tumors occur in geriatric patients. Malignant melanomas, nontonsillar squamous cell carcinomas, and fibrosarcomas are the three most common oral tumors in dogs. Squamous cell carcinoma occurs anywhere in the oral cavity and is by far the most common oral tumor that occurs in the cat. Metastasis due to oral tumors is rare with the exception of melanomas, high-grade sarcomas, and tonsillar squamous cell carcinomas in both the dog and cat.Before obtaining a biopsy specimen or attempting surgical resection of an oral tumor, the clinini- cian should confirm the general good health of all dogs and cats with a complete blood count, biochemical profile, total thyroxine (T4) level, and urinalysis. Thoracic radiographs should be obtained to rule out macroscopic pulmonary metastases. Fine- detail radiographs of the affected area may provide information on the aggressiveness of the tumor. Any local lymphadenopathy should be further investigated by fine-needle aspiration or biopsy performed at the same time as tumor biopsy. In a small percentage of cases, tumor metastasis can be demonstrated in lymph nodes that are not enlarged. Therefore the recommendation is to aspirate and potentially perform a biopsy of the regional lymph nodes in every case. The parotid and medial retropharyngeal lymph nodes should be evaluated. A fine-needle aspirate may in fact provide useful information regarding metastatic disease secondary to malignant oral tumors.The surgical approach for lymph node staging of oral and maxillofacial neoplasms in dogs has been described.
The first surgical excision is the most likely to result in tumor control; therefore appropriate planning is essential. The tumor should not be scraped or peeled from underlying bone, as recurrence is certain and the tumor bed will be enlarged. A definitive aggressive first surgery, such as max- illectomy or mandibulectomy, should be performed in cases where the tumor involves bone. Prompt diagnosis followed by aggressive treatment often results in improved survival and local tumor control.
Specific oral tumors in dogs and cats, the staging of these tumors, and their treatment options are discussed below.