Did you know that dogs with allergies are also prone to getting ear infections? Ear infections are often a secondary symptom of underlying allergies, especially allergies to dust mites, molds, pollens, and animal proteins in dog foods. Causes & symptoms of ear infections in dogs. Your dogs ears naturally have yeast and bacteria in them, but ear infections occur when the ear becomes moist and inflamed with increased wax and discharge. This allows the yeast and bacteria to multiple and ...