Diseases of the pinna

Many diseases can affect the pinna of the dog and cat. These diseases represent most categories of cutaneous disease, from infectious to neoplastic. Although some diseases affect primarily the pinna, most pinnal dermatoses occur in conjunction with other integumentary disorders. One should approach the diagnostic work-up of pinnal disease in an organized manner, obtaining first a thorough history and physical examination. A systematic approach is required in the diagnostic evaluation in order to arrive at a tentative or definitive diagnosis. Skin scrapings, cytologic examination, and culture for dermatophytes provide the minimum database. A variety of diagnostic tests, including hematology, serum biochemical profiles, urinalysis, serology, intradermal skin testing, hypoallergenic diet trials, histopathology, and direct immunofluorescence, may be necessary in some cases before a definitive diagnosis is reached. The ears are somewhat difficult to biopsy, although in many instances histopathologic examination is essential to the diagnosis. In this author's opinion, it is preferable to use a no. 15 scalpel blade rather than a punch biopsy when obtaining a pinnal biopsy. This allows the veterinarian to obtain an elliptical or wedge biopsy, which can frequently be sutured. In some instances, biopsies are required from the ear margin and a full ear thickness biopsy is obtained. Sutures may not hold in this situation, and cautery may be necessary for hemostasis. As in other situations in which the ear is bleeding (aural hematomas, vasculitis, fly bite dermatitis, and so on), bandaging and immobilization of the ear may be necessary to prevent further trauma. Although symptomatic therapy is sometimes helpful when treating pinnal diseases, a definitive diagnosis is preferred. This is especially important following the second or third presentation of an animal for ear disease. Although ear diseases are frequently viewed as a nuisance rather than a serious condition, anyone who has owned or worked closely with an animal suffering from chronic otitis externa should appreciate the animal's discomfort and the owner's frustration. All too frequently, the chronic otitis externa is the result of a hypersensitivity (either inhalant or food) that has been overlooked in the attempt to treat the subsequent infectious otitis. Thus, in animals with recurrent otitis externa, every attempt should be made to identify and treat the underlying etiology.