Ear Infections in Dogs: Signs, Causes and Treatment

What it is

Otitis externa is inflammation of the lining of the outer ear canal, and it is the most common type of ear infection in dogs. A dog's canal is L-shaped, so fluid, wax and debris get trapped easily, giving bacteria and yeast a warm place to grow.

The infection itself is often the last link in a chain. The Merck Veterinary Manual stresses finding every possible cause, because unless all of them are treated the problem often comes back. Common underlying reasons include allergies, mites, a foreign object or a hormonal problem.

Typical signs are head shaking, scratching or rubbing the ear, redness, swelling, a bad smell and dark or yellowish discharge. One or both ears can be affected. Untreated infections can cause a painful blood-filled swelling of the ear flap, and deeper infections can damage the eardrum and spread to the middle or inner ear, which can lead to balance trouble or hearing loss.

Causes and risk factors

What you can do at home

Do not treat a suspected infection at home. Over-the-counter drops, vinegar, powders and old leftover medicines can irritate the ear and, if the eardrum is damaged, can harm hearing. Merck specifically warns against vinegar mixtures, which can worsen swelling, and against powders after hair plucking, which can form irritating clumps. Your vet has to identify the exact cause before choosing a treatment.

Do not push cotton swabs into the canal, which can pack debris deeper, and avoid paper towels, which can leave fibers behind. Merck suggests real cotton balls and the AKC prefers absorbent gauze, so use what your vet recommends. Ask your vet before trimming or plucking hair near the canal.

Once your dog has been diagnosed, give the full course of medicine exactly as directed, without gaps or early stops, and keep every recheck appointment. If your vet recommends a cleaner, the AKC describes filling the canal with the solution, massaging the base of the ear from outside and then wiping away debris with gauze.

Do not over-clean, since that can strip the ear's natural protection. Dry the ears thoroughly after baths and swimming. See a vet if the ear looks worse, your dog seems painful or the smell returns.

What happens at the vet

The vet will look into the canal with an otoscope to check for foreign objects, mites, growths and, importantly, the eardrum. They will also take a sample of the discharge and look at it under a microscope to see whether bacteria, yeast or mites are involved. Chronic or severe cases may need a culture, and a very painful or blocked ear may need sedation or anesthesia for a proper look.

Treatment usually starts with cleaning and drying the ear, since wax and discharge can deactivate medication. Most ear drops combine an antibiotic, an antifungal and an anti-inflammatory. Severe cases may also need oral medicine. If the eardrum has ruptured, some drugs are unsafe because they can cause hearing loss, which is why the exam comes first.

The AKC says uncomplicated infections often clear within one to two weeks, while severe cases or ones with an underlying cause can take months. Ongoing allergies or thyroid problems need treatment too. When chronic inflammation narrows the canal permanently, surgery may be recommended. VCA notes that nearly all diagnosed and treated infections can be managed successfully, though the outlook is less favorable if an underlying cause goes unfound.

Prevention

Ear checks should become a habit. Regularly look and sniff for redness, swelling, moisture, discharge or a changed smell, and call your vet if anything looks off.

Dry the ears after every bath and swim. Clean only when it is needed, using a cleaner your vet approves and gauze or real cotton balls rather than swabs. Over-cleaning can cause problems of its own.

For floppy-eared or hairy-eared dogs, the AKC suggests keeping the hair near the canal opening neat, but Merck advises checking with your vet before trimming or plucking hair near the canal, so ask first.

Manage underlying problems. If allergies are involved, treating them often calms the ears, and our page on allergies in dogs explains what vets look for. Keep up with parasite control, which helps prevent ear mites.

If a food allergy is suspected, the AKC says an elimination diet typically lasts 8 to 12 weeks and must be strict, so run it with your vet rather than switching foods yourself. A dog with frequent head shaking should see a vet rather than get a new cleaner, as a recurring problem usually has a cause that needs treatment.