Because animals conceal their oral pain and dysfunction, oral tumors often develop and progress for prolonged periods of time before they are discovered.
Oral tumors can be classified as either benign or malignant. Benign tumors are not associated with metastasis (spreading throughout the body), however, they can still cause severe problems by expansion locally. Malignant tumors more commonly metastasize. Whether benign or malignant, tumors that grow rapidly (aggressive biologic behavior) can cause severe destruction of soft tissue and bone, which causes impairment of oral function. When gingiva and oral mucosa are damaged by a tumor, oral bacteria invade the tumor and cause infection.
Benign and malignant oral tumors can have similar appearances, especially at early stages, so oral tumors cannot be identified as benign or malignant based on visual inspection. Biopsy of the tumor is needed to diagnose the tumor type and biologic behavior, and imaging, such as dental radiographs are needed to determine the degree to which the tumor has invaded surrounding tissues. Understanding of the tumor type, biologic behavior, and extent is required for treatment planning. Dental radiographs and advanced imaging such as computed tomography (CT or CAT scan) are used in determining the extent of a tumor. CT scans are especially useful when the tumor extends beyond the oral cavity. In addition, for malignant tumors, checking for spread to lymph nodes and vital organs is important.
Once the tumor type, biologic behavior, and extent are known, the treatment plan is made. Whenever feasible, complete surgical excision (removal) of oral tumors is the first choice of treatment. Tumors that have been completely excised, and have not already metastasized will not recur or spread. For this reason, planning to completely excise a tumor so that it never recurs or metastasizes is referred to as “curative intent.” Sometimes, a tumor may be too large to be removed completely, or complete removal would severely compromise the pet’s quality of life. In these cases, palliative treatment, focused on providing good quality of life without addressing the tumor, is warranted.
When major surgery is required to completely excise a tumor, further reconstructive surgery can improve oral function and esthetic appearance.