Initially the skin may look inflamed and crusty consistent with sun damage. Eventually non-healing ulcers develop which ultimately invade and destroy the surrounding tissues or become fleshy masses which spread into the surrounding tissues. In the mouth SCC most frequently involves the base and underlying structures of the tongue. Nasal tumors appear as an ulcerated area often with a surrounding zone of loss of pigment near the nasal opening which can spread to invade and errode the nasal bones.

Most SCC rarely metastasize (spread to other parts of the body) or do so late in the course of the disease, however those tumors which do pread such as oral SCC can be very aggressive.

Treatment depends on location and stage of progress of the tumor. Lesions on the ear may be treated by amputation or cryosurgery (freezing) of the effected section of pinna. Radiation therapy has been successful in treating moderated lesions on all parts of the body. Radical resection (removal) of the nose has been effective in removing the tumor but has aesthetic problems (looks bad). Intralesional chemotherapy using cisplatin (injecting into the lesion) has been successful in treating skin based SCC however this does carry the risk of potentially fatal side effects in cats. The survival times for cats diagnosed with oral SCC is around 2-3 months despite treatment. Animals with skin based SCC if treated early enough have very good survival rates.