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Vet’s Corner
Otitis Externa (OE) is an ear condition characterised by inflammation of the ear
canal, and occasionally the pinna (outside flap of the ear).

Symptoms include:

• Head shaking
• Scratching at the ears
• Redness and swelling in the ear canal
• Discharge from the ears
• Foul odor
• Pain when the ears are touched or rubbed
• Loss of hearing or balance

If the ear canal is narrowed, this can encourage infection from bacteria and
yeasts. It can affect both ears at once or just one and can be acute (sudden
onset) or chronic (long-term).

What causes it?

- Parasites (e.g. the ear mite, Otodectes cyanotes)
- Allergies (food allergies, environmental allergies, contact hyper-
sensitivities)
- Trauma (excessive ear cleaning or scratching)
- Endocrine disease (e.g. hypothyroidism)
- Foreign bodies (e.g. grass seeds)
- Aural polyps
- Cancer

The most common cause is allergies (atopic dermatitis).

The main perpetuating factor is bacteria (most commonly Staphylococcus spp and
Pseudomonas spp) and yeasts (most commonly Malassezia spp). If the infection
spreads it can reach the middle ear (past the eardrum), causing a condition called
otitis media.

Risk:

Dogs with longer ears are more at risk of developing otitis externa, such as
Basset Hounds and Beagles. Dogs with erect ears have a lesser risk than other
breeds. Brachycephalic breeds, like the Pug or French Bulldog, are more likely to
develop otitis externa.

Dogs who are predisposed to atopic dermatitis are also predisposed to otitis
externa. In addition, dogs exposed to moisture, such as through regular
swimming, are at increased risk. Dogs who are overweight, or produce more
cerumen (ear wax) are also at risk.

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