Causes of otitis externa

Otitis externa is the most common disease of the canine and feline external ear canal and is defined as inflammation of the canal, with an underlying reason for the infection and inflammation in essentially all cases. It is most important to note that the bacteria or yeast organisms associated with cases of otitis externa are invariably only opportunists and are not primary pathogens that are solely responsible for a given case of otitis externa. Even in instances when the problem does not recur after appropriate treatment, the infection present should still be considered the result of a transient nonrecurrent insult to the external ear canal. Therefore, in cases where the initial treatment is temporarily effective but infection recurs, one must develop a systematic approach to identify the underlying problem resulting in the recurrent nature of the disease. If this is not accomplished, the opportunistic bacteria and yeast organisms invariably become increasingly resistant to the various topical antimicrobial agents used over time, to the point where the infectious organisms may become resistant to all available antimicrobials.