Discovering the causes of otitis externa

Otitis externa is one of the most common reasons why dogs present to veterinary surgeons in primary care practice. It is a much less common problem in the cat. This article outlines a logical approach principally to canine otitis externa. It describes the need to identify and manage primary causes of otitis, especially allergy which is the most common of these. Emphasis is placed on the fact that the more chronic the otitis, the greater the need to investigate its underlying cause rather than treat symptomatically. Secondary infections are discussed, particularly the need to perform cytology and where appropriate culture and sensitivity, in order to select specific antimicrobial therapy. The need to identify and manage both predisposing factors, such as conformation, and perpetuating factors, such as chronic change and otitis media are outlined. However, it is emphasised that these factors contribute to disease and should never be treated without addressing both secondary infection and primary causes.