Otitis Externa and Ear Infections in Dogs

Laurie Anne Walden, DVM

Otitis externa, or inflammation of the outer ear canal, causes itchy or painful ears and is common in dogs. Dogs with otitis externa often develop ear infections.

Otitis externa affects the part of the ear from the eardrum outward. Inflammation or infection that extends farther into the ear causes otitis media (middle ear disease) or otitis interna (inner ear disease).

Causes
Allergies to environmental substances (pollens, dust, etc) or to food ingredients are the most common causes of otitis externa in dogs. Other causes include parasites like ear mites, endocrine disorders like hypothyroidism, and immune system disorders.

Risk factors that make dogs more likely to develop otitis are long droopy ears, narrow ear canals, lots of hair in the ear canals, and growths in the ear canals. Plucking hair from the ear canals, cleaning the ears aggressively, and using harsh ear cleaners may damage the cells lining the ear canal and increase the risk for otitis externa.[1,2]

Depending on the cause, otitis externa can be a chronic problem that requires lifelong management. Dogs with allergies sometimes have flares of otitis even if the condition is under control most of the time.

Symptoms
Symptoms of external ear disease vary according to severity, individual dogs’ tolerance to discomfort, and whether infection is present. Most dogs with otitis externa have 1 or more of these symptoms:

• Head shaking
• Scratching 1 or both ears
• Odor from ears
• Whimpering when ear is touched
• Avoiding having head touched
• Redness at ear canal opening
• Crusts, discharge, or bleeding at ear canal opening
• Hair loss, redness, or scratches on ear flap
• Ear hematoma (swelling of the ear flap caused by blood accumulation under the skin)

Some dogs with long-term or recurrent otitis externa develop end-stage ear disease. These dogs have chronic ear pain (although they might not show obvious signs of pain), narrowed ear canal openings, hardened ear canals, and possibly hearing loss.
 
Diagnosis
The diagnosis of otitis externa is usually made by physical examination and history. Cytology, or examination of material from the ear canal under a microscope, is used to diagnose infection, identify the type of infection (bacteria, yeast, or both), and monitor the response to treatment. Examination of the canal and eardrum with an otoscope is helpful but not always possible in dogs with painful ears unless they are sedated. Other diagnostic tests can include bacterial culture of ear canal contents and imaging studies like radiography or computed tomography. Your veterinarian might recommend additional tests to find the underlying cause if your dog has had multiple episodes of otitis externa.
 
Treatment
Medications to treat ear infections include topical ear drops, oral medications, and medicated ear washes. The type of medication used depends on the type of infection and the severity of inflammation. The underlying cause of otitis is also treated as needed.
 
Many medications prescribed for ear infections contain anti-inflammatory drugs like corticosteroids. These medications reduce redness and itching, so the symptoms will improve before the infection has resolved. The best way to be sure the infection has actually cleared up is to follow your veterinarian’s dosing directions (how often and how long to use the medication) and to return for ear cytology rechecks as your veterinarian recommends.
 
Prevention
For many dogs, especially those with allergies, otitis externa can’t be completely prevented. Work with your veterinarian to manage the factors that contribute to your dog’s otitis and watch for symptoms so you can catch ear infections early.
 
References
1. Bajwa J. Canine otitis externa - treatment and complications. Can Vet J. 2019;60(1):97‐99.
2. Paterson S. Topical ear treatment - options, indications and limitations of current therapy. J Small Anim Pract. 2016;57(12):668‐678. doi:10.1111/jsap.12583
 
Photo by Ryan Walton

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