Also, as a rule, most breeds have a much longer ear canal than humans. These differences predispose the dog's ear to infection as well as make treatment more difficult. Dogs with long, pendulous ears, such as Cocker Spaniels, Labrador Retrievers, Basset Hounds and Irish Setters, certainly are more predisposed to ear problems than those breeds with short, erect ears. As the ear folds, it covers the ear canal and prohibits air from entering and drying the canal. The result is a moist, warm ear canal that is a perfect environment for organisms to grow.
Ear mites are parasites that often can cause otitis externa .
However, the incidence is much lower than often thought. In my experience, less than 10 percent of all ear problems in dogs that I have treated are the result of ear mites. Ticks and fleas are other examples of parasites commonly found in canine ear canals. Ear mites can be problematic, however. He said his old setter would sleep by the fireplace.