SQUAMOUS-CELL CARCINOMA OF THE TONGUE IN 10 DOGS

Ten cases of squamous cell carcinoma (SCC) of the tongue in dogs were reviewed. There was no breed or sex predilection. All were middle aged to older with a median age of 9.5 years (range 7 to 13 years). Eight underwent treatment. All had excision of the tumor which resulted in removal of 40% to 60% of the tongue. Adjuvant chemotherapy with mitoxantrone was used in three and radiation therapy in two. Three histological grades of SCC were distinguished by taking into account such indicators of malignancy as lack of keratinization, poor differentiation, mitotic rate, and tumor invasion of surrounding vessels and tissues. Dogs that had tumors with a more malignant histological appearance (grade III) had a poor prognosis (one of four survived). The metastatic rate was 37.5% (three of eight treated dogs). Four of the eight (50%) that were treated are alive at 6, 12, 16, and 27 months with no evidence of residual disease. Resection of 40% to 60% of the tongue was well tolerated.