Cat Ear Infections (Otitis): Causes, Symptoms and Treatment

A cat pawing at one ear, shaking its head, or holding an ear at an odd angle is easy to mistake for a passing itch. Often it's otitis — inflammation inside the ear canal — and it's one of the more common reasons cats end up at the vet for something that isn't obviously an emergency. Otitis isn't a single disease; it's a description of what's happening (an inflamed, irritated ear canal), and the actual cause can be a parasite, a yeast overgrowth, a bacterial infection, or an underlying allergy that's letting all three take hold. Sorting out which one you're dealing with matters, because the wrong treatment can make a cat more uncomfortable for weeks while the real problem goes on untreated.

A veterinarian explains what causes ear infections and how they're treated.

What's Actually Causing It

Otitis in cats is usually driven by one of a handful of underlying triggers, and it's common for more than one to be present at once:

• Ear mites (Otodectes cynotis). Especially common in kittens and cats with outdoor access. Produces a dark, dry, coffee-ground-like discharge and intense itching. Highly contagious between pets in the same household.
• Yeast (Malassezia) overgrowth. The ear canal naturally hosts a small amount of yeast; when the environment shifts — often due to excess moisture, allergies, or a disrupted skin barrier — it multiplies out of control. Produces a brown, waxy discharge and a distinctive musty or "cheesy" smell.
• Bacterial infection. Often secondary to yeast overgrowth, mites, or a scratch from itching. Discharge tends to be yellow, green, or blood-tinged, and the ear is often visibly red, swollen, and painful to the touch.
• Underlying allergies (food or environmental) are frequently the root cause behind recurring yeast or bacterial otitis — the allergy inflames the ear canal's skin, and infection follows. A cat with ear infections that keep coming back, rather than one isolated episode, should be worked up for an underlying allergy rather than just re-treated each time.
• Polyps or masses are a less common but important cause in older cats, and are one reason a vet exam matters rather than guessing from symptoms alone.

Recognising the Symptoms

Watch for any combination of these, and don't wait for all of them to appear before getting it checked:

• Scratching or pawing at one or both ears
• Head shaking or a persistent head tilt
• Dark, waxy, or foul-smelling discharge visible inside the ear
• Redness, swelling, or heat inside the ear canal
• A visibly painful reaction when the ear or the base of the ear is touched
• Loss of balance, or holding the head consistently tilted to one side — this can signal a more advanced middle- or inner-ear infection and warrants prompt veterinary attention

A quick rundown of the warning signs to watch for at home.

How Vets Diagnose the Cause

The reason a vet visit matters more than a guess-and-treat approach at home is that mites, yeast, and bacteria all cause similar-looking symptoms but need different medication:

• Otoscopic exam. A lighted otoscope lets the vet see how deep the inflammation goes, check the eardrum is intact, and look for mites, polyps, or foreign material directly.
• Ear cytology. A swab of the discharge, smeared on a slide and examined under a microscope, identifies whether yeast, bacteria, mites, or a mix are present — this single quick test is what actually determines the treatment plan.
• Culture and sensitivity testing is sometimes used for infections that don't respond to first-line treatment, to identify the specific bacteria and which medication will work against it.

Treatment: Why It Depends on the Cause

• Ear mites are treated with a topical parasiticide (often the same product used for fleas) plus a thorough ear cleaning to remove debris; every pet in the household typically needs treating at the same time to stop reinfestation.
• Yeast infections respond to an antifungal ear medication, usually combined with a gentle cleaning routine to keep the canal dry, since yeast thrives in a moist environment.
• Bacterial infections need a prescription antibiotic ear medication, chosen based on what the cytology or culture shows — over-the-counter human ear drops are not appropriate for cats and can worsen inflammation or be toxic if the eardrum is compromised.
• Cleaning technique matters. A vet-approved cat ear cleaner, applied by massaging the base of the ear and letting the cat shake out the loosened debris, is far safer than cotton swabs, which pack debris deeper into the canal and risk injury.
• Recurring cases usually need an allergy work-up (food trial, environmental allergy testing, or both) once the active infection has cleared, since treating the infection alone without addressing the underlying trigger just sets up the next flare.

A vet explains how yeast infections develop in cats' ears and how they're managed.

Preventing Repeat Infections

• Check your cat's ears weekly as part of a normal grooming routine, so you notice a change early rather than after it's established.
• Keep ears dry after bathing — towel-dry the outer ear and avoid letting water pool in the canal.
• Use a vet-recommended cleaner on a routine schedule only if your vet has actually advised it; cleaning healthy ears too often can disrupt their natural balance and cause the very problem you're trying to prevent.
• Keep flea and mite prevention current, especially for cats with any outdoor access.
• If infections keep recurring, push for the allergy work-up rather than accepting repeat rounds of drops as normal — it's usually the faster route to actually fixing it.

The Bottom Line

An itchy, smelly, or painful ear is uncomfortable for a cat and rarely resolves on its own. Because mites, yeast, and bacteria look alike from the outside but need different treatment, a same-week vet visit with a quick cytology test is worth far more than guessing with an over-the-counter product. Caught early and treated for the actual cause, most cases clear up within one to two weeks with no lasting effect on hearing or balance.

This article is general information, not veterinary advice. Talk to your vet about diagnosis and treatment tailored to your individual cat.