How common are ear infections in dogs?

Very common. A UK study of more than 22,000 dogs found about 7.3 percent diagnosed with otitis externa in a single year, and ear infections rank as one of the top conditions dogs are seen and insured-claimed for.

Why does my dog keep getting ear infections?

Because the infection is usually a symptom, not the root problem. The most common underlying cause is allergy (environmental or food), which inflames the ear canal and lets bacteria or yeast overgrow. If the allergy is not addressed, the infection comes back no matter how many times you treat the ear.

What are the signs of a dog ear infection?

Head shaking, scratching or rubbing at the ear, an odor, brown or yellow discharge, redness and swelling inside the ear, and pain when the ear is touched. A head tilt or balance problems can signal the infection has reached deeper into the ear.

Can I treat my dog's ear infection at home?

It is best not to guess. Different causes (bacteria, yeast, ear mites) need different medications, and the vet uses ear cytology, looking at a swab under a microscope, to choose the right one. Cleaning the ear and using vet-prescribed drops, plus treating the underlying cause, is what actually resolves it.

What happens if a dog ear infection goes untreated?

Chronic untreated infections can rupture the eardrum, spread to the middle ear, and cause the canal to thicken and scar. In end-stage cases the only fix is major surgery to remove the canal, which is why catching and controlling infections early matters.

Dog Ear Infections (Otitis Externa): Why They Keep Coming Back

Here is the short version: ear infections are one of the most common reasons dogs go to the vet, and one of the most maddening, because they keep coming back. The trap is treating the ear as the problem. In most dogs the infection is a symptom of something else, usually an allergy, and until that underlying cause is handled, you are stuck in a cycle of drops and relapses. This guide explains why ears get infected, why your vet swabs them, and how to break the loop for good.

One of the most common reasons dogs see the vet

This is a high-frequency problem. A UK study of more than 22,000 dogs found about 7.3 percent diagnosed with otitis externa (inflammation of the outer ear canal) in a single year.¹ In US insurance data, ear infections rank as the second most common condition dogs are seen for, just behind skin allergies, which is a telling pair, as you will see.³

~7.3%

of dogs are diagnosed with an ear infection in a single year; it ranks #2 among canine vet visits

O'Neill et al., VetCompass 2021; Nationwide claims

The infection is usually a symptom, not the cause

Here is the insight that changes how you treat it. The Merck veterinary reference frames otitis as something that almost always sits on top of an underlying primary cause, and the single most common one is allergy, either environmental atopic dermatitis or food allergy.² In a study of 100 dogs with ear disease, allergic skin disease was the leading primary cause, found in 43 of them.⁴ Allergy inflames the ear canal, changes its environment, and lets the bacteria and yeast that normally live there harmlessly overgrow into an infection.

Other primary causes exist, ear mites (especially in young animals and cats), a foreign body like a grass seed, hormonal disease, or growths, and some dogs are simply built for trouble with floppy, hairy, or narrow ear canals. Moisture from swimming is a predisposing factor that tips a vulnerable ear over the edge.² But for the dog that keeps relapsing, the smart money is on an unaddressed allergy, which is why this article links hands with our guide to canine atopic dermatitis.

The signs

Ear infections are usually easy to notice once you know what to look for:²

Head shaking and scratching or rubbing at the ear.
An odor, and discharge that may be brown, waxy, or yellow.
Redness and swelling inside the ear, and pain when you touch it.
A head tilt, circling, or balance trouble, which can mean the infection has reached the middle or inner ear.

Why your vet swabs the ear

This step is not busywork, it is the key to getting treatment right. The vet takes a swab and looks at it under a microscope, called ear cytology, to see whether the overgrowth is bacteria, yeast (Malassezia), or whether mites are present.² Those need different medications, and the discharge alone can be misleading. Merck is explicit that cytology is central to choosing the right treatment.² Guessing, or reusing leftover drops from last time, is how infections get undertreated and resistant.

How it is treated, and how to stop the relapses

Treating the active infection usually means a thorough ear cleaning plus a topical medication, often a combination that covers bacteria, yeast, and inflammation.² That clears the current flare. The part that actually breaks the cycle, and the focus of modern veterinary thinking on recurrent otitis, is identifying and managing the underlying cause.⁵ If allergy is behind it, that means an allergy work-up and plan, not just another round of drops. Ears that keep getting treated without the cause being addressed reliably relapse.²

The stakes for leaving it unmanaged are real. Chronic, repeated infections can rupture the eardrum, extend into the middle ear, and cause the canal to thicken and narrow until it no longer responds to medication. The end-stage fix is a major surgery to remove the ear canal, which is exactly the outcome early, cause-focused care is meant to prevent.²

What it costs

A straightforward infection, an exam, cytology, and medication, is usually modest, commonly in the range of $150 to $500 in the US depending on the workup. The costs that hurt come at the far end: end-stage surgery to remove a ruined ear canal can run several thousand dollars per ear. These are market estimates that vary by region. The cheapest path, by far, is catching infections early and fixing the allergy that keeps causing them.

What to do this week

If your dog is shaking its head or scratching an ear, book a vet visit rather than reaching for old medication, the cause needs identifying first.
Ask your vet to run ear cytology so the treatment matches what is actually growing.
If this is the second or third infection, ask directly about an underlying allergy and a plan to manage it.
Dry your dog's ears gently after swimming or baths, especially if it has floppy or hairy ears.

An ear infection looks like a simple, local problem, and that is exactly why it keeps winning. The dogs that get off the relapse treadmill are the ones whose owners and vets stop chasing the ear and start treating the cause. Clear the infection, then ask the harder question, why did it happen, and you usually find the answer is not in the ear at all.