The tongue plays many vital roles in the oral cavity of the dog and cat. Consequently, lingual lesions can have devastating effects on an animal's overall health. This article provides a review of tongue anatomy as well as a review of the etiology, gross appearance, and diagnostic procedures indicated for a wide variety of lingual lesions. Lingual pathologic conditions that are reviewed include traumatic, metabolic, idiopathic, infectious, immune-mediated, hereditary, and neoplastic lesions. This article also describes current concepts in the medical management of lingual lesions.