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Otitis Externa - Ear Infection

2015-07-01

Otitis Externa is inflammation of the external ear canal.  In some cases the pinna (ear flap) and or middle ear may also be affected.  Many factors can be involved in otitis externa developing; these can be divided into 3 main categories, Predisposing factors, primary causes, and perpetuating factors.  The common signs to look for  are discharge and odor from the ear, redness or swelling of the ear, rubbing or pawing at the ear, shaking of the head, and decreased hearing ( not be confused with selective hearing).
Predisposing factors can be breed or individual specific factors that change the environment of the ear canal, making them more susceptible to bacteria and yeast infect ions. The most common of these are pendulous or floppy ears, narrow ear canals, excessive hair in the canal, and frequent swimming.  Otitis externa can affect any dog or cat; we most commonly see issues in Cocker Spaniels, Golden Retrievers, Labrador Retrievers, and Miniature Poodles.Primary causes include conditions that directly inflame the ear.  Parasites, plant material, such as grass awns, allergic skin issues, autoimmune diseases that attack the skin, hormonal disorders, masses in the ear such as benign polyps or tumors, foreign bodies are some of the causes commonly seen. 

Perpetuating factors are factors that prevent resolution of the ear inflammation or worsening of an existing ear disease. Examples of perpetuating factors include bacteria, yeast, inflammation of the middle ear, and changes in the ear canal such as swelling, scarring and or mineralization of the tissue. 

Diagnosis of Otitis Externa is done with physical examination of the ear. Often an otoscope is used to determine the amount of debris in the ear canal, look for changed to the ear canal and tissue, and evaluate the tympanic membrane (ear drum). The ear canal is swabbed and the material collected is examined under the microscope to look for bacteria, yeast and ear mites. In some cases the swab may be submitted for bacterial culture. Diagnosis of underlying diseases often requires further tests such as Laboratory and hormonal tests, allergy testing, skin scraping or biopsies. 

Treatment goals of Otitis Externa are to remove the debris from the ears, relieve inflammation and resolve infections. Cleaning the ears is a crucial part of treating Otitis Externa, using an ear cleaning solution with a drying agent is ideal. Avoid using products such as Hydrogen Peroxide that can be damaging to the tissue and potentially do more harm to the sensitive ear skin.  Once debris is removed ointments that include antibiotics and antifungals are commonly used to treat infection in the ear. Steroids are used to help with swelling and inflammation. . In severe cases oral medications may be added to the topical applied to the ear.  Specific treatment for an underlying condition may also be required. 

Prognosis of Otitis Externa is good if treatment is early, and resolution of primary, predisposing, and perpetuating factors is controlled. Some cases may not be cured and animals may need regular ear cleaning to prevent infections from re occurring. Chronic and recurrent otitis externa may require more attention and possibly surgery.