If you’ve ever had a dog with a sticky, smelly ear, then you’ve had a dog with otitis externa.
The word “otitis” refers to an inflammation of the ear, and the “externa” part is the external ear canal, the tube down which sounds travel to reach the eardrum.
There is a lot of misunderstanding about otitis externa. Although infections may seemingly occur for no reason, the vast majority of animals who have repeated ear infections are subject to underlying factors driving the condition that may include swimming (water in the ear), allergies, parasite infections or even having an underactive thyroid gland.
Treatments include topical products containing antibiotics, but in an ideal world, the underlying cause is identified and tackled to make the next episode of otitis less likely.
For people with drop-eared dogs, the first clue your pet has an infection is that awful smell that follows the dog from room to room.
Lifting the earflap then reveals that the skin around the ear canal is inflamed and reddened. If the infection is well established, often the skin is thickened (if in doubt, compare one ear with the other). There may also be a discharge from the ear canal that is purulent or sometimes a thick, waxy substance.
Ear infections are painful, and the animal tilts his head down on the infected side or else shakes and scratches the ear.
The simple answer (but perhaps not the full story) as to the causes of otitis externa include invasion of the ear canal by bacteria, yeasts or parasites. However, these are usually opportunists who seize on the ear’s weakened immune defenses to cause infection.
One example is the dog who loves to go swimming. He gets water in his ears, which macerates the skin (think of prune-like fingers when you soak in the bath), making it vulnerable to infection.
The most common underlying reason is allergy, be it to allergens in the environment or food intolerance, and this causes the skin to become inflamed. These patients often have sore skin, with the infection working its way from the outside in (i.e., extending from the entrance to the ear and down into the canal).
Your vet makes a diagnosis after a physical exam of the ears. This includes looking down inside the long L-shaped ear canal with an otoscope.
However, this is a catch-22 situation — often the animals who need their ears examined are too sore and painful to allow it. In this case, the veterinarian may suggest either sedating the animal for a thorough look without distress or starting a course of anti-inflammatories and oral antibiotics to reduce swelling and soreness ahead of the next exam.
When trying to identify the bugs present in the ear canal, cytology is helpful. This is where the clinician smears some of the discharge onto a slide and looks at it under the microscope. This helps the veterinarian decide if a culture is necessary and which antibiotic is most effective.
This veterinarian gives stellar tips on how to help your dog recover from otitis externa:
A heavy discharge in the ear acts as a barrier to the penetration of a topical medication.
Thus ear cleaning and de-bulking the pus or wax is an important step, after which topical medicated drops can be used. If the infection is severe, then sedation to flush the ear clean is a great idea, and the pet may also need oral antibiotics.
If the pet suffers recurring infections, it is then appropriate to investigate any underlying causes. This may include putting the animal on a hypoallergenic diet, blood tests checking thyroid function and investigations into possible allergies.
If an allergy is identified as weakening the ear canals’ defenses, then controlling the allergy goes a long way in decreasing the chances of otitis. However, often it is a case of control rather than cure and keeping a wary eye on predisposing factors, such as swimming.
- “Otitis externa — seeing past the signs to discover the underlying cause.” Woody & Fox. Vet Med Small Anim Clin, 87: 616.
- “A practitioner’s approach to complete ear care.” Wilson. (1985). Dermatology Reports, 4.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 11, 2018.