Ear Infections in Cats and Dogs: A UK Owner's Guide to Causes, Treatment, and Prevention

Why ear infections happen

The ear canal is dark, warm, and humid — ideal conditions for bacteria and yeast. Most healthy ears stay free of infection because the body's defences keep microbe levels in check. When something disrupts that balance, infection takes hold.

The primary causes are:

• Allergies (environmental atopy or food) — by far the most common underlying cause of recurrent ear infections in dogs
• Anatomical predisposition — floppy ears (Spaniels, Bassets), narrow canals (Shar Peis, French Bulldogs), hairy canals (Poodles, Schnauzers)
• Excess moisture — swimming dogs, frequent bathing without proper drying
• Foreign bodies — grass seeds (a particular problem in summer; can be a true emergency if they migrate), small debris
• Parasites — ear mites are the most common cause in puppies and kittens; less common in adults
• Hormonal disease — hypothyroidism, Cushing's
• Polyps and tumours in the ear canal (cats more than dogs)

Once the conditions are right, secondary bacterial or yeast (usually Malassezia) infection takes hold quickly. Treating the secondary infection without addressing the primary cause is why so many ear infections recur.

Warning signs to watch for

• Head shaking or rubbing the ear or face on the floor or furniture
• Scratching at the ear — sometimes obsessively
• Tilting the head to one side, particularly the affected side
• Smell — a yeasty, sweet, or sharp odour from the ear
• Discharge — yellow, brown, black, or bloody. Brown waxy discharge is most common.
• Redness or swelling of the ear flap or canal
• Pain on touching the ear — the dog flinches, vocalises, or pulls away
• Hot ears
• Loss of balance, walking in circles, or drooping eye/face on one side — indicates the infection has reached the middle or inner ear; needs prompt vet attention
• In cats: often subtler — head tilt, scratching, or grooming the affected ear excessively. Polyps in cats can present with persistent low-grade signs that look like a chronic infection

If your dog has been swimming or romping in long grass and shows sudden severe ear discomfort, particularly head shaking and pawing, see a vet the same day — a grass seed in the ear canal can migrate and cause significant damage if not removed promptly.

What diagnosis involves

A typical UK consultation:

1. History and clinical examination — the vet will check both ears with an otoscope (a magnifying instrument with a light), looking down the canal for redness, debris, foreign bodies, and the eardrum.
2. Cytology — a swab of the ear discharge is examined under the microscope. Almost always reveals the type of infection (yeast vs bacteria, sometimes both, occasionally rod-shaped bacteria that suggest specific resistant organisms).
3. Culture — in resistant or recurrent cases, sending a sample to the lab to identify the exact organism and which antibiotics it responds to.
4. Considering the underlying cause — for first-time mild infections, the focus is on clearing the current episode. For recurrent cases (more than 2–3 times in a year), the conversation needs to shift to identifying the primary driver — usually allergy.
5. Sedated ear examination and flushing for severe cases, very painful ears, dogs where the canal is too inflamed to see down properly, or where a foreign body is suspected. Allows thorough cleaning and proper assessment of the eardrum.

Treatment

For a typical bacterial or yeast infection:

• Cleaning — the vet usually flushes the ear at the consultation. You'll then continue gentle cleaning at home with a veterinary cleaning solution, typically every 2–3 days during treatment.
• Topical medication — ear drops containing an antibiotic, antifungal, and anti-inflammatory in one preparation. Used once or twice daily for 1–2 weeks typically. Some newer preparations are single-application long-acting (one dose lasting a week or two).
• Pain relief — oral anti-inflammatories for the first few days if the ear is significantly painful.
• Recheck appointment — increasingly important. A repeat cytology at the end of treatment confirms the infection is fully cleared. Stopping treatment when the symptoms improve but before the infection is gone is one of the main reasons infections recur.

For severe, deep, or middle-ear infections, oral antibiotics and longer treatment courses are sometimes needed. For ears so severe that medical management can't restore them, surgical procedures (TECA-BO — total ear canal ablation) are available at referral level for end-stage cases.

For recurrent cases driven by allergy, addressing the allergy itself (see our skin conditions guide) usually transforms the picture.

Reducing recurrence

For dogs prone to ear problems:

• Routine cleaning with a vet-recommended ear cleaner — typically once a week or after swimming. Don't over-clean; healthy ears need their natural balance.
• Drying ears thoroughly after swimming or bathing
• Address the underlying cause — allergy management is the single highest-impact intervention for chronic recurrent cases
• Avoid using cotton buds at home
• Recheck visits to catch early recurrence before it becomes a full infection
• For floppy-eared breeds: keeping ear hair trimmed (or plucked, depending on breed and vet advice) where appropriate to improve airflow

Typical UK costs in 2026

• Initial consultation + cytology + cleaning + medication: £80–£200
• Recheck visit: £35–£70
• Bacterial culture (if needed): £80–£150
• Sedated ear flush: £200–£500
• Specialist (otitis-focused) referral: £200–£500
• TECA-BO surgery (end-stage cases): £2,500–£5,000+

Most lifetime insurance policies cover ear infections. Recurrent cases benefit from a policy with no per-condition cap or with sufficient annual cap to cover frequent visits.