Ear Infections in Dogs: Signs and Preventing Relapse

Constant head shaking, scratching at the ears and a foul smell are familiar signs of an ear infection. It's one of the most common reasons dogs visit the vet. What frustrates many owners is how often ear infections return, clearing up only to come back a few weeks later. Understanding the underlying cause is the key to breaking that cycle.

Signs of an ear infection

• Head shaking or tilting the head to one side.
• Scratching the ears, rubbing them on the floor or sofa.
• Red, swollen, warm skin on the inner ear flap.
• A foul, sour or yeasty smell.
• Dark brown, yellow or black wax, or discharge and pus.
• Pain, flinching or crying out when the ear or head is touched.
• An ear flap that swells up like a water balloon: possibly an aural hematoma from vigorous head shaking.
• More serious: loss of balance, circling, flickering eyes, reduced hearing. The infection may have spread to the middle or inner ear.

Why dogs get ear infections so often

A dog's ear canal is long and L-shaped, running down and then across, so moisture and wax build up easily. When the ear environment is disrupted, bacteria and yeast that are normally present overgrow. Common factors:

• Allergies: food allergies or environmental allergies such as house dust and pollen are the most common root cause of recurring ear infections. Allergic dogs often also lick their paws, scratch their face or have an itchy belly.
• Ear shape: floppy or long ears and lots of hair in the ear canal.
• Moisture: water in the ears from bathing or swimming; humid weather.
• Parasites: ear mites, common in puppies, cause black, coffee-ground wax and intense itching.
• Foreign bodies: grass seeds or sand in the ear canal.
• Incorrect cleaning: pushing cotton swabs too deep, cleaning too often, or using alcohol or hydrogen peroxide.
• Hormonal disease: conditions such as hypothyroidism can make the skin and ears more prone to inflammation.

Treatment: why a vet visit matters

Each ear infection needs its cause identified: bacteria, yeast, ear mites or a foreign body. Your veterinarian will usually look into the ear and examine a wax sample under the microscope. This also checks the eardrum, because some ear drops can cause harm if the eardrum is ruptured.

• Use the right ear drops or ear cleaner, in the right way and for the full course, as directed by your veterinarian. Read the product label carefully.
• Don't stop treatment as soon as the ear looks better. Stopping early is a common reason infections return.
• Don't use human ear drops or leftover medicine from a previous episode.
• Go to follow-up visits so your vet can confirm the ear has fully cleared.

Preventing relapses

1. Find and manage the root cause: if your dog gets ear infections several times a year, ask your vet about allergies. An elimination diet under guidance, or managing environmental allergies, may be needed.
2. Keep ears dry: when bathing, cover the ears or avoid spraying water directly into them. After baths or swimming, dry the ear flap and outer ear canal with a soft towel.
3. Check ears weekly: look at the skin color and sniff for odor. Early detection makes treatment much easier.
4. Clean in moderation: use a dog ear cleaner as your veterinarian advises, wiping only the visible part. How often depends on the dog; healthy ears don't need frequent cleaning. See our related article on cleaning your dog's ears.
5. Ear canal hair: ask your vet whether your dog needs it trimmed. Don't pluck ear hair yourself unless shown how, as it can cause irritation.
6. Ear mite prevention: when a new puppy or kitten joins the household, have its ears checked early, as ear mites spread between dogs and cats.

When to see a vet

• Head shaking, ear scratching, red ears or a bad smell for more than a day or two.
• Discharge, pus or blood from the ear, or pain when touched.
• A sudden swelling of the ear flap.
• Head tilt, loss of balance, circling or flickering eyes: go right away.
• Ear infections that recur several times a year despite treatment.
• A suspected grass seed or object in the ear after running through grass.