Otitis Externa

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Also Known As

Ear canal infection


Otitis externa occurs when the ear canal of the horse becomes infected causing pain and swelling in the ear canal. The first sign of otitis externa may be head shaking by the horse. Typically, ear infections begin with otitis externa and then progress deeper into the canal to the middle ear unless treated effectively.

If not treated promptly and effectively, the inflammation becomes chronic and may lead to rupture of the eardrum, partial deafness, and neurological problems.


  • Head shaking
  • Swelling and redness within the ear
  • Tenderness when ear is touched
  • Discharge of pus with a bad odor


In horses, the cause of otitis externa is usually a tick or a foreign body that is in the ear for a prolonged period of time leading to infection and inflammation. Sometimes, infections on the horse's ear flap may invade the ear canal. Allergies, and illnesses such as auto-immune diseases also may lead to otitis.


Routine checking and cleaning of the horse's ears, including removal of ticks and foreign objects, will catch most external problems in the early stages.


Removal of any ticks or foreign bodies plus a thorough cleaning of the ear canal is the most important step in treating external otitis. In most cases, the horse will need to be sedated and restrained during the cleaning.

Topical medications, such as an antibiotic-corticosteroid ear preparation, are used to treat the infection, and a veterinarian may suggest oral medications to help kill bacteria before the infection spreads to the inner ear.

If otitis externa is the result of a disease or because of an allergy or tumor that blocks the ear canal, these conditions will need to be treated in order to clear the infection.

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