Any one of several problems can cause the ear canal to become filled with odoriferous debris. Your pet will probably tell you its ears are uncomfortable by excessive scratching and head shaking. Early treatment of ear problems is important to prevent complications such as damage to the inner ear and hearing loss. Ears infected with mites are often filled with dark brown, flaky debris. The mites can be seen when the debris is examined under a microscope.
Allergies are a common cause of ear irritation in dogs.
Allergies can be caused by pollens, molds, plants, fleas, and a variety of other substances. In addition to scratching their ears, dogs with allergies often lick their feet and rub their face. Trauma to the ear from foreign objects, such as plant seeds or burrs, or from aggressive cleaning with cotton-tipped applicators can also cause pain and inflammation in a pet's ears. Any of these conditions, if left untreated, can lead to additional and more complicated problems, such as yeast or bacterial infections. These infectious agents grow best in warm, humid ears that have little air flow.