If your dog keeps shaking its head or scratching one ear raw, otitis externa (outer ear infection) is the most likely culprit. It is one of the most common reasons dogs visit the vet — and one of the most frequently under-treated.
Signs Something Is Wrong
- Head shaking or tilting to one side
- Scratching the ear or rubbing it on furniture
- Redness, swelling, or discharge (dark wax, pus, or a yeasty smell)
- Pain when the ear is touched; yelping or pulling away
- In severe cases: loss of balance or a head tilt that does not resolve
Common Causes
- Yeast (Malassezia) — head-shaking with a musty, sweet-sour odor
- Bacteria — often secondary to another problem, producing pus
- Allergies — environmental or food allergies are the #1 underlying trigger in recurring cases
- Ear mites — more common in puppies, producing dark “coffee ground” debris
- Moisture & anatomy — swimming, frequent baths, or narrow ear canals trap moisture
- Foreign bodies — grass awns or foxtails, common after summer walks
How Vets Treat It
Treatment is based on what is actually growing in the ear, so the vet will usually swab the canal and look at it under a microscope (cytology). Typical plan:
- Professional cleaning to remove debris so medication can reach the skin
- Medicated drops — antibiotic, antifungal, and anti-inflammatory combinations, usually for 1–3 weeks
- Pain relief if the ear is very sore
- Treating the root cause — allergy management, parasite control, or dietary changes for repeat cases
Home Care (and What NOT to Do)
- Use only ear cleaner recommended by your vet; never pour water or hydrogen peroxide into the canal.
- Never insert cotton swabs deep into the ear — you can rupture the eardrum.
- Keep the ear dry: gently wipe the outer flap after swimming or bathing.
- Finish the full course of drops even if the ear looks normal after three days.
Prevention
Dry the ears after every swim or bath, check them weekly, keep allergies managed, and use vet-approved parasite prevention. Dogs with hairy or narrow canals may need regular cleaning as part of their grooming routine.
Disclaimer: this article is educational and not a substitute for professional veterinary advice. Ear infections can rupture an eardrum if left untreated — see your vet.