Proliferative and Necrotizing Otitis Externa of Cats and Kittens.

Proliferative and necrotizing otitis externa (PNOE) is characterized by thick, adherent dark red, brown, or black crusts. It most commonly affects the concave pinnae and vertical ear canals bilaterally. Lesions may also be seen on the face, and it may rarely present in a generalized form. There is no known cause of PNOE, but it responds to treatment with topical and systemic immunomodulatories and is therefore thought to be immune-mediated. Twenty-one cases have been described in the literature and are summarized here.