Your dog is on its fourth course of ear drops this year. Each one works. Each time, it comes back within a couple of months.
That is not bad luck and it is not a resistant infection. It is what happens when the thing being treated is a symptom and nobody has gone after the cause.
Why do ear infections keep coming back?
Otitis externa is a multifactorial disease, and the most important thing to understand is the layering.
The primary cause is what started it. In dogs, that is most often allergy, atopic dermatitis or an adverse food reaction. Allergy inflames the ear canal lining, changes its microclimate, and turns it into somewhere yeast and bacteria can flourish.
The secondary infection is what your vet is treating. Malassezia yeast, staph, sometimes Pseudomonas.
Predisposing factors make it easier: floppy ears, hairy canals, humidity, swimming.
Perpetuating factors keep it going: chronic thickening of the canal, scarring, middle-ear involvement.
Drops target the second layer. If nobody addresses the first, the ear is back in three months, and each cycle thickens the canal a little more, which makes the next one harder to clear.
So the question to bring to your vet after the second infection in a year is not "can we try different drops?" It is "what is the primary cause here, and how do we investigate it?"
The test to insist on: cytology
If you take one thing from this article, take this.
Ear cytology is a swab of the canal rolled onto a slide, stained, and examined under a microscope. It is quick, in-house, inexpensive, and it is recommended for all dogs with otitis externa.
It tells your vet:
- Yeast, bacteria, or both, which determines the drug entirely
- Rods versus cocci, rod-shaped bacteria raise the possibility of Pseudomonas, which is a harder, more serious infection needing a different approach
- How much inflammation is present
- Whether treatment is working, when repeated afterwards
Without it, treatment is a guess dressed up as a prescription. An antifungal will do nothing for a bacterial infection, and a broad-spectrum antibiotic in a yeast-driven ear makes the yeast worse.
How to ask, without friction: "Could we do a cytology before we choose the drops?" Most vets will do it as a matter of course. If it is not offered, it is a reasonable and specific thing to request.
What an ear infection looks like
- Head shaking, or tilting to one side
- Scratching at the ear, or rubbing that side of the face along furniture and floors
- Smell, usually the first thing an owner notices
- Discharge: brown and waxy, yellow, or dark and crumbly
- Redness inside the flap and down into the canal
- Pain when you touch the ear, a dog that has always let you handle its ears and suddenly pulls away
- Reluctance to have that side of the head touched at all
In a monsoon month, add: an increase in all of the above across the whole household of dogs at once. Humidity favours yeast, and yeast otitis is seasonal in a way that catches people out every year.
How to clean ears properly
Only clean if your vet has confirmed there is no ruptured eardrum, and only with a proper ear cleaner.
- Fill the canal with cleaner to the level of the opening. Be more generous than feels right, a timid dribble does nothing.
- Massage the base of the ear for about 15 seconds. You should hear a squelch. This is what breaks up the debris deep in the canal.
- Let your dog shake its head. This is the step that brings material up and out. Stand back.
- Wipe away what has come up with cotton wool or gauze, on your finger, no deeper than you can see.
- Repeat until the cotton comes back clean.
Never use cotton buds. They push debris deeper and can damage the eardrum. The dog's own head-shake is the extraction mechanism. Your job is only to soften and wipe.
Do not over-clean. A healthy ear does not need daily cleaning; the canal is self-cleaning and excessive interference irritates it. Clean at the frequency your vet sets.
Do not put anything in a painful, swollen or bleeding ear before it has been examined. If the eardrum is ruptured, some cleaners and medications can cause permanent damage, including deafness.
Do not use hydrogen peroxide, vinegar solutions, or spirit from the internet. They sting badly in an inflamed canal and some worsen the inflammation they are meant to fix.
When it is more than an ear infection
See a vet urgently for:
- Head tilt, loss of balance, circling, or flicking eye movements. This suggests middle or inner ear involvement, not simple otitis
- Sudden deafness
- A swollen, boggy ear flap, an aural haematoma, from shaking hard enough to burst a blood vessel; common, and it needs treating
- An ear so painful the dog will not let it be touched. That dog may need sedation to be examined properly, and forcing it is neither kind nor useful
Breaking the cycle
If your dog has had two or more ear infections in a year, the plan should look like this:
- Cytology at every episode, infections change character between episodes
- Full ear examination including otoscopy once the canal is clear enough to see down
- Investigate the primary cause, an elimination diet trial if food is suspected, and atopy management if environmental
- Look at the rest of the dog, a dog with recurrent otitis and itchy paws has one disease, not two
- Maintenance plan, the right cleaner at the right interval, not the maximum
That is a longer path than another bottle of drops. It is also the only one that ends with an ear that stays well.
The bottom line
An ear infection is a symptom. In dogs, the thing it is most often a symptom of is allergy.
Get cytology every time, clean properly and not excessively, never use a cotton bud, and after the second infection in a year, start asking about the cause rather than the cure.
Recurrent ear disease alongside paw licking, or itching around the face and belly, is the classic atopic pattern, one condition presenting in several places, not several conditions.