I am often faced with patients who have been repeatly treated for ear infections. These dogs have usually been treated with multiple agents and often many times. Otitis Externa (OE) is the medical lingo for an infection of the outer ear canal. These infections can be bacterial or yeast. So the first step in evaluating ear infections is to do a full physical exam because OE is symptom, not a diagnosis. There is always an underlying cause and so additional symptoms need to be detected. The second step is to do a cytology to determine whether we are dealing with bacteria or yeast and this is needed to select the appropriate drug. Beyond that a true diagnosis needs to pursued. The most common cause of OE is allergic skin disease. This may be confusing at first until you view the ear lining as a continuation of the dog's skin. It is specialized skin, but skin regardless. So ear infections often become a heralding sign of progressing allergic disease. The other disease that leads chronic ear infections is hypothyroidism. Both allergic disease and hypothyroidism require a thorough diagnostic work-up. Once the cause is determined then the real treatment can begin. Without a diagnosis owners are usually resigned to treating OE over and over. So next time your dog is shaking his ears make sure you insist on a complete workup. Anything else is like rearranging the deck furniture on the Titanic.