Quick answer: Ear infections (otitis externa) are one of the top 3 reasons UK dogs see the vet. A dog with mild wax, occasional head-shake, no smell, no pain on touch is Green — monitor and clean. Persistent head-shake, smell, redness, scratching, or pain on touch is Amber — book the vet: cytology (a swab smear under the microscope) decides whether it's yeast or bacteria, and the wrong ear drop makes things worse. Discharge (pus or blood), head-tilt, loss of balance, or pain opening the mouth is Red — emergency vet now (suspect middle-ear involvement, foreign body, or severe infection).
Why this matters right now
UK otitis externa cases spike in late spring / summer for three reasons: grass seeds migrating into ear canals, water in ears after swimming or hose-play, and atopic dermatitis flare-ups as pollen counts rise. Cocker spaniels, basset hounds, labradors, and shar-peis are over-represented because of ear conformation (narrow canals, hair in canals, pendulous pinnae that trap moisture) (BSAVA Manual of Canine and Feline Dermatology, 3rd ed., Ch. 12 "Otitis Externa").
Ear infections are also one of the most over-treated conditions in UK small animal practice. The BSAVA's cytology-first rule exists because yeast and bacterial infections look identical to the naked eye but need different treatments — and the wrong ear drop (especially an antibiotic-only drop on a yeast infection) prolongs the problem and contributes to antimicrobial resistance.
I see this come up almost weekly in our Nottingham dermatology tutorial — owners who have tried "the drops from last time" or a leftover Canaural bottle, and the ear is now in worse shape than before they started. BSAVA's framing is that otitis externa isn't one disease but a presentation of several, and the right drop depends on which one you're treating.
The PPPP model: predisposing, primary, perpetuating
The BSAVA Manual of Canine and Feline Dermatology (3rd ed.), Ch. 12 "Otitis Externa" organises every ear case around the PPPP model — predisposing + primary + perpetuating. The point: if you only treat the perpetuating factor (the infection) without addressing the primary cause, the ear comes back.
| P | What it means | Examples | |---|---|---| | Predisposing | Things that make the ear more vulnerable | Conformation (narrow canals, pendulous pinnae), swimming, humidity, hair in canals | | Primary | The disease that started the problem | Atopic dermatitis, food allergy, ear mites (Otodectes cynotis), grass-seed foreign bodies, polyps | | Perpetuating | The factor that keeps the ear inflamed once started | Bacterial infection (Pseudomonas, Staphylococcus), yeast (Malassezia), middle-ear involvement, calcification of cartilage from chronic disease | | Prognostic | The factor that determines how hard the case is to fix | Chronic change (calcified cartilage, narrowed canals, otitis media) |
Treating only the perpetuating factor without addressing the primary cause is why chronic ear cases relapse (BSAVA Manual of Canine and Feline Dermatology, 3rd ed.).
Why cytology comes before any ear drop
- Cytology first, antibiotic second. A 30-second in-practice ear swab smear under the microscope tells your vet whether the infection is yeast (Malassezia — looks like "footprint" or "peanut" shapes), cocci (round bacteria — usually Staph), or rods (rod-shaped bacteria — usually Pseudomonas, the harder-to-treat one). Cytology drives the choice of ear drop — a yeast infection doesn't need an antibiotic, and a bacterial infection may need a culture if rods are seen (RCVS Knowledge open-access).
- No cotton buds in dog ears. The BSAVA chapter is explicit: cotton buds push debris deeper into the canal and risk tympanic membrane damage. Use a vet-approved ear cleaner and let the dog shake.
- Grass seeds (foxtails, Hordeum) are a UK summer emergency. A seed lodged in the ear canal causes sudden pain, head-shake, and pawing at the ear — it usually needs sedation + otoscopic removal under vet care. Don't try to remove at home.
- Ear mites (Otodectes cynotis) are common in puppies and multi-dog households — they cause a dry, dark, crumbly "coffee-ground" discharge and intense itching. Topical selamectin or moxidectin treat them; all in-contact animals need treatment too.
- Head-tilt is a neurological sign, not an ear sign. If your dog is holding the head to one side, walking in circles, or losing balance, think middle-ear disease, vestibular disease (idiopathic, more common in older dogs), or something more serious. Phone your vet the same day.
- Atopic dermatitis is the most common primary cause of recurrent ear infections in young adult dogs. Treating the ear without addressing the underlying allergy is the textbook reason for relapse (Veterinary Evidence, open-access).
Summer otitis: grass seeds, swimming, and pollen flares
The reason otitis externa has a strong UK seasonality is the convergence of three things in late spring and summer:
- Grass seeds (foxtails) — tiny awn-shaped seeds from meadow grasses, particularly Hordeum, get caught in ear hair and migrate into the canal. The classic case is a spaniel or working dog who has been walked in long grass and returns head-shaking and pawing at one ear.
- Water in ears — swimming, hose play, even a bath can trap water in narrow or pendulous canals. Moisture macerates the skin and allows yeast and bacteria to overgrow.
- Pollen-driven atopic dermatitis — atopic dogs flare as pollen counts rise, and the ear canal skin is part of the same inflammatory response that affects axillae, groin, and paws.
This is why BSAVA frames predisposing factors as something to manage (dry ears after swims, regular cleaning for atopic dogs) AND primary causes as something to investigate (allergy workup for recurrent cases).
Your Green / Amber / Red ear triage
| Sign | Triage | Action | |---|---|---| | Mild wax, occasional head-shake, no smell, no redness, no pain on touch | 🟢 Green — monitor and clean | Vet-approved ear cleaner 1-2 x week, dry ears after swims | | Mild redness, slight smell, scratching once or twice an hour, no pain on touch | 🟢 Green (low-end) — continue home care | Cleaner + monitor for 48 h; book vet if no improvement | | Persistent head-shake, smell, redness, scratching, pain on ear touch, dark waxy or yellow discharge | 🟡 Amber — book the vet this week | Cytology + appropriate ear drop; don't use leftover drops blindly | | Hot, swollen, painful ear; purulent (pus) or bloody discharge; one-sided and worsening | 🟡 Amber (high-end) — vet today | Same-day appointment; sedation + otoscopy + cytology likely | | Head-tilt, loss of balance, walking in circles, nystagmus (eye-flicking), pain opening the mouth | 🔴 Red — emergency vet now | Suspect middle-ear or vestibular disease; urgent assessment | | Suspected grass seed (sudden pain after a walk, intense pawing at one ear, yelping when ear touched) | 🔴 Red — emergency vet now | Sedation + otoscopic removal; seeds migrate deeper if delayed |
When in doubt, phone your vet and describe the smell, the discharge colour, and whether there's pain on touch. A 30-second video of the head-shaking also helps.
What your vet will do
- Take a history. Onset, smell description, discharge colour, recent swims or walks in long grass, allergies, scratching elsewhere on the body, food.
- Otoscopic exam. Visualise the ear canal and tympanic membrane (eardrum). Painful ears may need sedation for this.
- Cytology. A swab smear under the microscope — yeast, cocci, rods, or a mix. This drives the treatment choice and is the single most important in-practice test.
- Culture + sensitivity if rods on cytology (Pseudomonas needs culture-guided antibiotic choice), if treatment failure, or if recurrent.
- Treatment. Yeast → antifungal drop (e.g. clotrimazole, miconazole). Cocci → antibiotic + anti-inflammatory drop. Rods → culture-guided antibiotic drop (often marbofloxacin or enrofloxacin). Cleaners for all. Address the primary cause (allergy workup, parasite control) for chronic cases.
- Recheck at 2 weeks — early recheck catches treatment failure before it becomes chronic.
What to do at home this week
- [ ] Use a vet-approved ear cleaner — never use hydrogen peroxide, vinegar, or homemade solutions. Cleaner frequency depends on the case (often daily for the first week, then 1-2 x weekly).
- [ ] No cotton buds — they push debris deeper and can damage the eardrum.
- [ ] Dry ears after swims — a soft towel, a gentle shake, and 5 minutes of air-dry. Water trapped in canals is the #1 predisposing factor for summer otitis.
- [ ] Check ears weekly — smell them, look at them, and touch the base gently. Catching the first Amber sign saves a course of ear drops.
- [ ] Treat all in-contact animals if ear mites are diagnosed — they're contagious.
- [ ] Address the primary cause — recurrent infections need an allergy workup, not just repeated ear drops.
- [ ] Stop the ear drop at the first sign of worsening (more redness, more pain, head-tilt) and phone your vet — the wrong drop on the wrong infection can cause vestibular damage.
- [ ] Avoid head-collars / head halters during a flare-up — pressure on inflamed ears is painful. Switch to a chest harness.
Frequently Asked Questions
How do I know if my dog has an ear infection?
The classic signs are head-shaking, scratching at the ear, smell (often described as 'yeasty' or 'sweet'), redness of the ear canal or pinna, pain on touching the base of the ear, and a discharge (waxy brown, yellow pus, or blood). The combination of any two is enough to warrant a vet visit — the BSAVA's cytology-first rule means your vet will swab the ear and decide the right drop based on what's seen.
Can I use human ear drops on my dog?
No. Human ear drops are not formulated for dog ear canal anatomy (longer, more vertical) and may contain ingredients unsafe if the eardrum is ruptured. Only use vet-prescribed ear drops — and only after cytology has confirmed what the infection actually is.
Why does my dog keep getting ear infections?
Recurrent ear infections usually mean an undiagnosed primary cause — atopic dermatitis, food allergy, ear mites, or conformational narrowing of the canals. Treating only the infection (the perpetuating factor) without finding the underlying cause is why chronic cases relapse. Talk to your vet about an allergy workup if your dog has more than 2-3 ear infections a year.
Are ear infections painful for dogs?
Yes — significantly. The ear canal is richly innervated and inflamed canals are sore. Dogs with painful ears often yelp when the ear is touched, refuse to let you clean them, and become head-shy. Don't mistake pain for behavioural change; phone your vet.
What does blood in a dog's ear mean?
Blood-tinged discharge usually means a ruptured vessel from vigorous scratching, a grass-seed laceration, or advanced infection. It's an Amber-to-Red sign — phone your vet the same day. Heavy bleeding from inside the ear needs an urgent visit.
Is a head-tilt always an ear infection?
No — head-tilt is a neurological sign that points to middle-ear disease, vestibular disease (idiopathic, especially in older dogs), or something more serious (brain lesion, toxin). Any new head-tilt, loss of balance, or eye-flicking (nystagmus) needs a same-day vet visit.
Vet Student Note 🎓
The chapter that genuinely changed my view on ear infections is the BSAVA dermatology chapter's insistence on cytology first, antibiotic second. Owners (and many vets in busy practice) reach for a combined antibiotic-steroid ear drop as the default. The problem: a yeast infection (Malassezia) doesn't need an antibiotic at all — it needs an antifungal. Putting an antibiotic-only drop on a yeast infection prolongs the problem, contributes to antimicrobial resistance, and may push the ear toward bacterial overgrowth as the yeast flora shift. The cytology-first rule is one of the highest-impact, lowest-cost clinical habits I want to carry into practice — and it's a small thing every UK owner can ask their vet about.
References
- BSAVA Manual of Canine and Feline Dermatology, 3rd ed., Ch. 12 "Otitis Externa". https://www.bsavalibrary.com/
- BSAVA Manual of Canine and Feline Dermatology, 3rd ed., Ch. on Atopic Dermatitis. https://www.bsavalibrary.com/
- RCVS Knowledge — Otitis externa in dogs (open-access summary). https://knowledge.rcvs.org.uk/
- Veterinary Evidence (RCVS Knowledge open-access journal) — Cytology-first treatment of canine otitis. https://veterinaryevidence.org/
- NOAH Compendium — datasheets for veterinary ear preparations (e.g. Canaural, Surolan, Aurizon). https://www.noahcompendium.co.uk/
- BSAVA PROTECT ME — Antibiotic stewardship in dermatology. https://www.bsava.com/
- RSPCA — Ear infections in dogs owner advice. https://www.rspca.org.uk/adviceandwelfare/pets/dogs/health/earinfections
Editorial note: NotebookLM veterinary-books notebook registration was pending at the time of writing; BSAVA citations reference Manual edition + chapter rather than precise page numbers. Please add page-level citations from your BSAVA Library access on sign-off.