Your cat's been shaking her head more than usual, and now there's a faint smell you can't quite place coming from one ear. You clean it, it gets better for a few days, then it's back. If this cycle sounds familiar, you're not doing anything wrong you're just treating the surface of a problem that has a deeper cause underneath it.

Ear infections in cats, known medically as otitis externa, happen when the lining of the ear canal becomes inflamed, and while bacteria are often part of the picture, they're rarely the actual starting point. Parasites, allergies, and foreign objects are usually what set the whole thing off which is exactly why an infection that keeps "coming back" often isn't really coming back at all. It's the same underlying trigger never having been fully addressed.

Key Takeaways

• Otitis externa is the most common ear canal disorder in cats, and it can affect one or both ears, with signs that come on suddenly or build up slowly.
• The real cause is usually a parasite, foreign object, or allergy bacteria and yeast are often secondary problems that pile on afterward.
• Diagnosis typically needs a proper otoscope exam and a microscope look at ear discharge, not just a visual glance.
• Treatment is layered: addressing the underlying cause, topical medication, sometimes oral or injected medication, and gently cleaning the ear first if there's too much discharge for topical treatment to work.
• Stopping treatment as soon as things "look better" is one of the most common reasons infections relapse your vet's recheck exists specifically to catch this.
• Prevention isn't about routine cleaning. It's about regular inspection and treating every pet in the household if a parasite is behind the problem.

What Is Otitis Externa in Cats?

Otitis externa is inflammation of the ear canal's lining, and according to the Merck Veterinary Manual, it's the most common ear canal disorder in cats. The ear canal's job is to carry sound to the eardrum, and when its lining becomes inflamed, that whole system gets disrupted which is part of why an ear infection doesn't just feel uncomfortable, it can genuinely affect a cat's hearing while it's active.

What Are the Signs of an Ear Infection in Cats?

The Merck Veterinary Manual lists a fairly recognisable set of signs: head shaking, odour, redness, swelling, scratching, increased discharge, and scaly skin. The ear flap (pinna) can be affected alongside the canal itself, and the canal itself might be painful or itchy to the touch. One or both ears can be involved, and importantly signs can appear suddenly or build up over a long period, which means a slow-developing infection is just as real a concern as a sudden one, even if it's easier to dismiss at first.

What Actually Causes Ear Infections in Cats?

This is the part most pet parents get slightly wrong, understandably it's easy to assume "ear infection" means "bacterial infection," and reach straight for an antibacterial product. The Merck Veterinary Manual is specific that the real picture is layered: causes include parasites, foreign objects, and allergies that directly trigger inflammation, while bacteria, yeasts, and middle ear infections can add to the problem on top of that underlying trigger. Identifying all the contributing factors not just the bacteria visible on a swab is essential to treat the infection and keep it from coming back.

Parasites: The Most Overlooked Cause

Ear mites are a genuinely common driver of feline ear inflammation, and they're easy to miss without a proper microscope exam, since the resulting inflammation can look similar to a straightforward bacterial infection at first glance. If mites are the actual cause and only the secondary infection gets treated, the mites keep irritating the ear canal, the inflammation keeps returning, and the "infection" appears to relapse again and again when really, it never fully left.

Allergies

Ongoing or recurring ear inflammation without an obvious parasite or foreign object present is often a sign of an underlying allergy either environmental (atopy) or food-related. This is one of the harder causes to pin down, since it usually needs a broader allergy work-up rather than a single ear swab, but it's worth raising with your vet directly if your cat's ear infections keep coming back despite otherwise appropriate treatment.

Foreign Objects and Structural Issues

A blade of grass, a seed, or debris lodged in the canal can trigger inflammation on its own, and the resulting swelling and discharge then create exactly the environment bacteria and yeast need to take hold. This is one of the reasons a vet uses an otoscope rather than relying on a visual glance from outside foreign material deep in the canal simply isn't visible without one.

How Do Vets Diagnose Otitis Externa in Cats?

Diagnosis starts with a detailed history and a thorough exam the Merck Veterinary Manual notes that scratching, redness, skin changes, ear deformities, abnormal tissue growth, and head shaking all point toward ongoing discomfort that's worth investigating properly rather than dismissing as a passing itch.

Getting an actual look inside the canal often needs more than a cat sitting still for a peek. Cats might need sedation or anaesthesia to let the vet use an otoscope, especially if the ear is painful, blocked with discharge, or the cat is simply uncooperative a completely reasonable response to a sore ear. This tool helps identify foreign objects or polyps, impacted debris, parasites, and eardrum problems that a surface glance would miss entirely. Ear swabs examined under a microscope are what actually confirm whether bacteria, yeast, or mites are present, rather than guessing from appearance alone.

For cases that don't add up cleanly, additional tests can include allergy testing, and persistent, one-sided blockage might need a biopsy to rule out a tumour. If the middle or inner ear could be involved suggested by signs like head tilting or balance changes alongside the ear symptoms x-rays, CT, or MRI may be needed to see past the outer canal entirely.

How Are Ear Infections in Cats Treated?

Treatment in otitis externa is genuinely layered, and understanding why helps explain some of the steps that might otherwise seem unnecessary.

Addressing the underlying cause comes first. The vet treats the actual trigger and manages pain alongside it this is the step that determines whether the infection actually resolves or just quiets down temporarily.

Topical medication is the mainstay for most cases. Most topical ear medications combine antibiotics, antifungals, and steroids to decrease inflammation, and proper application means coating the inside of the canal with a thin film not just a drop or two near the opening.

Oral or injected medication steps in for tougher cases. This is often used for long-term canal inflammation or when the middle ear is suspected to be involved, since topical treatment alone may not reach deeply enough.

Ear mites get their own specific treatment. They're treated with antiparasitic drugs, not antibiotics which is exactly why correctly identifying mites as the cause (rather than assuming bacteria) genuinely changes the treatment plan.

Cleaning often comes before medicating, not instead of it. Discharge and wax can make topical treatments less effective, so vets may gently clean and dry the ears first, sometimes under anaesthesia if the ear is too painful for a cat to tolerate cleaning while fully awake.

Treatment continues until the infection has actually resolved, not until it looks better on the surface. The Merck Veterinary Manual notes your vet will recheck your pet to ensure therapy isn't stopped too soon this recheck step is one of the most skipped parts of home treatment, and skipping it is a common reason infections seem to "come back" a few weeks later.

Why You Shouldn't Use Home Remedies

Pets shouldn't be treated with home remedies like hydrogen peroxide or vinegar. These can irritate already inflamed canals and increase secretions, which actually promotes the development of bacterial or yeast infections rather than solving anything. Only use ear products and cleaning methods your vet has specifically recommended for your cat's particular situation what worked for a friend's cat, or what a pet store clerk suggests, isn't a substitute for a diagnosis.

How Can You Prevent Ear Infections in Cats?

Prevention here isn't what most people expect it's not about cleaning more often.

Inspect regularly, don't clean routinely. The Merck Veterinary Manual's preventive guidance is specific: inspect your cat's ears regularly for changes in skin temperature, colour, moisture, discharge, scabs, hair loss, or other abnormalities, and schedule prompt exams if you notice changes. Unless advised otherwise by a vet, healthy cats generally don't need routine ear cleaning at all.

Treat every pet in the household if mites are diagnosed. Mites spread easily between cats and dogs sharing the same space, bedding, or grooming tools, and treating only the symptomatic cat while everyone else stays untreated is a near-guarantee of reinfection within weeks.

Address allergies at the source. If recurring ear inflammation traces back to an allergy, managing the allergy itself not just treating each ear flare-up as a standalone event is what actually breaks the cycle long-term.

Check outdoor cats after time in long grass or undergrowth. Foreign material working its way into the ear canal is easier to catch early, before it triggers a full infection, if you get in the habit of a quick post-outing check.

Follow through on the full treatment course, including the vet recheck, even once symptoms have visibly improved. This single habit prevents more "recurring" infections than almost anything else on this list.

If you're not sure whether what you're noticing warrants a vet visit, our guide on 10 signs your pet is sick is a useful general reference alongside these ear-specific signs. And if your cat needs ear medication as part of treatment, our guide to giving cats medicine walks through a calm, effective technique for drops and topical products.

FAQ

Can ear infections in cats go away on their own?
Some very mild irritation might settle briefly, but a genuine otitis externa infection typically doesn't resolve without addressing its underlying cause. Left untreated, it tends to worsen, and can eventually spread toward the middle or inner ear, which is a more serious and harder-to-treat problem.

How long does it take to treat an ear infection in a cat?
It varies with the cause and severity, but most straightforward cases improve within one to two weeks of proper treatment. However, your vet's recheck is what confirms the infection has genuinely cleared, not just improved stopping early based on how things look is one of the most common reasons treatment needs to be repeated.

Why does my cat's ear infection keep coming back?
Recurring infections almost always point to an underlying cause that hasn't been fully addressed commonly ear mites, an untreated allergy, or a foreign object that was never actually removed. If your cat's infections keep returning despite treatment, it's worth asking your vet directly what's driving the recurrence, rather than repeating the same topical treatment each time.

Are certain cat breeds more prone to ear infections?
Cats generally get fewer ear canal infections than dogs, and there isn't a strong, well-documented breed pattern the way there is in some dog breeds with heavy, pendulous ears. Individual risk factors outdoor access, known allergies, or a history of ear mites matter more than breed in cats.

Is it normal for my cat's ear to smell after cleaning?
No a healthy, properly cleaned ear shouldn't have a noticeable odour. If a smell persists or returns quickly after cleaning, it usually points to an active infection that needs veterinary attention rather than further cleaning at home.

References

1. Roman, Nick. Otitis Externa (External Ear Infection) in Cats. Merck Veterinary Manual, Pet Owner Version.
2. Roman, Nick. Disorders of the Outer Ear in Cats. Merck Veterinary Manual, Pet Owner Version.