Canine and feline nasal and paranasal sinus tumors.

Tumors involving the nasal cavity and nearby sinuses are relatively rare in the dog and cat. Although the most common cause of unilateral epistaxis, facial deformity, and epiphora in the aged dog and cat is a malignant nasal or paranasal tumor, differentials must be considered. In each case, a definitive diagnosis is made on the basis of the signalment, history, physical examination findings, radiographs, and histologic evidence of malignant neoplasia. Although many treatment options exist, radiation therapy, with or without surgery, has been considered to be most effective.