The most common cause is allergies to something in the environment or, less often, to food.

Hypothyroidism can lead to skin changes, including recurrent infections like otitis externa.

Ear anatomy of some breeds can be a predisposing factor for otitis externa. Shar Peis’ stenotic ear canals is an example.

When a primary cause of otitis externa is left untreated, the condition is likely to reoccur.