The external ear canal begins at the outside of the ear and ends at the eardrum. Otitis externa is an inflammation of that part of the canal.
Otitis externa is a very common problem in dogs and is extremely difficult to cure. The condition is fairly common in cats and usually results from ear mite infestation.
Causes of otitis externa are numerous. Certain individual animals and breeds are predisposed, making the diagnosis and treatment more difficult. Factors responsible for inflammation of the outer ear include: ear mites, allergies (food, fleas, etc.), foreign bodies, wax, matted hair, debris, bacteria, and fungi. An infection located in a deeper area of the ear (otitis media) can also cause otitis externa.
The external ear canal is warm and moist, making it an excellent breeding ground for bacteria and fungi. Dogs with floppy ears, deep canals, and / or excessive hair in the ear canals are generally more susceptible to otitis externa.
A thorough otoscopic examination is necessary to diagnose otitis externa. Results of bacterial and fungal cultures, as well as cytology, are often important for determining the proper treatment. Often, manipulation of the ears is very painful and requires general anesthesia.
Long term treatment is usually necessary for controlling otitis externa. Frequent veterinary visits are often necessary. Some animals never seem to show much of an improvement. These animals may be candidates for lateral ear canal resection.