CONDITION

Otitis Externa in Cats

Otitis externa is inflammation of the external ear canal — the passage that runs from the visible ear opening down to the eardrum. In cats, it often appears as head shaking, ear scratching, or a darkened discharge visible at the ear opening, though some cats show little outward sign until the problem is quite developed. Owners typically notice their cat flicking one or both ears, holding the head tilted, or resisting touch around the ear. The discharge may be dry and crumbly, waxy and brown, or occasionally moist, depending on what is driving the inflammation. Ear mites are a common trigger in younger cats, while allergies, foreign material, polyps, and skin conditions play a role in others. Less commonly, the problem reflects an underlying immune or hormonal pattern. This page explores what prompts inflammation in the feline ear canal, what signals may be observed, how the ear is examined and sampled, and the range of approaches used to address both the inflammation itself and whatever is sustaining it.

Why this matters now

Otitis externa can appear at any age, though kittens and younger cats may be more prone to ear-mite infestations, which can trigger inflammation. Cats with underlying allergies — whether to food, environmental particles, or contact materials — may develop ear-canal inflammation as part of a wider pattern. Outdoor cats and those in multi-cat households may encounter more opportunities for mite transmission or trauma from scratching or fighting.

The condition often begins with mild irritation that the cat addresses by scratching or shaking its head. If the underlying cause persists or if bacteria or yeast begin to flourish in the altered canal environment, the inflammation may deepen and the discharge may change in character or volume. Some cats experience a single episode that resolves when the trigger is removed, while others develop a pattern that recurs over months or years, particularly when an allergic or anatomical factor remains in play.

Signals & patterns

Early signals

Head shaking or tilting

The cat may shake its head more often than usual, or hold one ear slightly lower, as though trying to dislodge something uncomfortable. This reflects irritation inside the canal that the animal is attempting to relieve.

Scratching at the ear

Repeated pawing or scratching at the base of the ear or the side of the head can signal discomfort. The skin around the ear may become pink or slightly abraded from the friction.

Visible discharge or wax

An owner may notice a small amount of brown, yellow, or dark material inside the ear canal when they lift the ear flap. The texture and colour can vary depending on what is growing or accumulating.

Unfamiliar odour

A sweet, yeasty, or unpleasant smell may become noticeable when the owner is near the cat's head. This often suggests that microorganisms are multiplying in the warm, moist canal.

Later signals

Thickened or reddened ear canal

The lining of the canal may become visibly swollen or inflamed, sometimes narrowing the opening. Chronic inflammation can lead to tissue changes that make the canal less able to drain or ventilate itself.

Reluctance to be touched

The cat may pull away, vocalise, or become defensive when the owner attempts to examine or handle the affected ear. This suggests that the canal has become tender or painful.

Persistent or heavy discharge

The volume of material may increase, sometimes appearing thick, purulent, or blood-tinged. This can indicate a deeper infection or ulceration of the canal lining.

Click to read about the biological mechanisms

How this is usually investigated

Investigation typically begins with a careful history—how long the problem has been present, whether it affects one or both ears, any previous episodes, and the cat's environment and behaviour. Direct examination of the ear canal using an otoscope allows the clinician to see the degree of inflammation, the nature and volume of any discharge, and whether the eardrum is intact and visible. From there, specific tests help identify the underlying cause and any secondary infections that may have established.

Otoscopic examination

Purpose: This allows direct visualisation of the ear canal and eardrum. The clinician can assess the degree of inflammation, identify foreign material or masses, and observe the character of any discharge present.
Considerations: Sedation or anaesthesia may be required if the ear is painful or the canal is narrowed by swelling. The view may be obstructed by discharge or severe inflammation, limiting what can be seen until the canal is cleaned.

Cytology

Purpose: A sample of discharge is examined under a microscope to identify ear mites, yeast organisms, or bacteria. This guides which antimicrobial treatments, if any, may be useful.
Considerations: Cytology reveals what organisms are present in the canal at that moment but does not identify the underlying reason they have overgrown. Ear mites are often visible as moving white specks or may be seen on the prepared slide.

Bacterial culture and sensitivity

Purpose: When infection is present and does not respond to initial treatment, culture identifies the specific bacterial species and tests which antibiotics are effective against it.
Considerations: Culture takes several days to yield results and is typically reserved for persistent or recurrent cases. It does not address why the infection developed in the first place.

Computed tomography (CT)

Purpose: Advanced imaging can reveal the extent of inflammation, identify polyps or masses within the middle ear or bulla, and assess bony changes in chronic cases.
Considerations: CT requires general anaesthesia and is usually considered when otoscopy suggests deeper involvement, when masses are suspected, or when medical management has not resolved the problem. It provides structural detail but cannot determine the specific tissue type of a mass without biopsy.

Histopathology

Purpose: Biopsy of masses or abnormal tissue within the ear canal provides a definitive tissue diagnosis, distinguishing inflammatory polyps from tumours and identifying the tumour type if present.
Considerations: Biopsy requires anaesthesia and is typically performed when imaging or otoscopy reveals a discrete mass. The procedure carries a small risk of bleeding or further inflammation in an already compromised ear.

Options & trade-offs

Management typically combines treatment of the inflammation and any secondary infection with efforts to address the underlying cause. The approach is shaped by what is found during investigation, the severity and duration of signs, and what is practical for the individual cat and household. Different combinations prove workable for different situations, and the plan often evolves as the ear responds or new information emerges.

Topical ear medication

Drops or ointments applied directly into the ear canal can deliver anti-inflammatory, antimicrobial, or antiparasitic agents where they are needed. Formulations vary widely; some address multiple problems in a single preparation, while others target a specific organism or reduce inflammation alone. Treatment duration depends on the underlying cause and the severity of infection.

Trade-offs: Application requires handling the ear, which some cats tolerate poorly, particularly when the canal is painful. Owners may find twice-daily treatment challenging over several weeks. Debris or severe swelling can prevent medication from reaching deeper portions of the canal until the ear is cleaned.

Ear cleaning and flushing

Removing discharge, wax, and debris allows better visualisation of the canal, improves contact between medication and inflamed tissue, and reduces the material that bacteria and yeast feed upon. Cleaning may be performed at home with appropriate solutions or under sedation or anaesthesia in the clinic when the ear is very painful or heavily obstructed.

Trade-offs: Overzealous or incorrect cleaning can damage the delicate lining of the ear canal or the eardrum if it is already compromised. Some cats resist the procedure, making home cleaning impractical. Professional flushing under anaesthesia is more thorough but incurs additional cost and the small risks associated with sedation.

Addressing underlying causes

When ear mites are identified, specific antiparasitic treatment eliminates the infestation. Allergies may require dietary trials, environmental modification, or anti-inflammatory medication to reduce the immune response driving ear canal inflammation. Polyps or tumours often require surgical removal, particularly when they obstruct the canal or extend from the middle ear.

Trade-offs: Treating the underlying cause takes longer to show effect than simply suppressing infection or inflammation, and the path forward may not be clear until initial investigations are complete. Allergy management can be a prolonged process with trial and adjustment. Surgery carries the risks inherent in any anaesthetic procedure and may involve referral to a specialist.

Systemic medication

Oral or injectable anti-inflammatory drugs, antibiotics, or antifungals may be used when infection or inflammation is severe, when topical treatment is impractical, or when the middle ear is involved. Some modern antiparasitic treatments administered systemically also address ear mites effectively.

Trade-offs: Systemic medication affects the whole body, not just the ear, and may carry a broader range of side effects than topical treatments. It can be easier to administer in cats that resist ear handling, though some cats are difficult to tablet. Duration of treatment and monitoring requirements vary with the drug and the severity of disease.

Common misconceptions

Misconception:

"Ear problems in cats are usually caused by water getting into the canal after grooming or bathing."

Reality:

Cats groom fastidiously but rarely get water deep into the ear canal in the way that dogs might after swimming. Feline otitis externa is far more commonly triggered by ear mites, allergies, or growths such as polyps. Moisture can contribute to secondary yeast or bacterial overgrowth once inflammation is already present, but it is seldom the initiating cause.

Misconception:

"If the ear looks clean and there is no discharge, the problem has resolved and treatment can stop."

Reality:

The underlying cause—whether mites, allergy, or a polyp—may still be present even when visible discharge has cleared. Stopping treatment prematurely often allows inflammation and infection to return. The prescribed course is usually designed to address both the surface signs and the deeper drivers, and its duration is guided by what was found during investigation rather than by appearance alone.

Misconception:

"Ear mites are only a problem in young or outdoor cats and do not spread to other pets."

Reality:

While ear mites are indeed common in kittens, they can affect cats of any age and living situation. The mites are contagious and can spread to other cats and dogs in the household through direct contact. Treating all susceptible animals in the home is often necessary to prevent reinfestation, even if only one is showing signs.

Related conditions

Otitis Externa in Dogs

Otitis externa in dogs shares the same anatomical site and many of the same underlying drivers—environmental disruption, allergy, infection, and anatomical factors—though cats and dogs can differ in the relative frequency of certain causes and the presentation of discomfort.

Atopic Dermatitis in Dogs

Atopic dermatitis in dogs represents a systemic allergic condition that often involves the ear canals as one site of inflammation; in cats, hypersensitivity conditions can similarly contribute to ear canal inflammation, though the underlying allergens and immune pathways may differ.

Pyoderma

Pyoderma describes bacterial infection of the skin, and the same opportunistic bacteria that proliferate in disrupted skin environments can overgrow within the ear canal when the normal protective barriers are compromised, contributing to or complicating otitis externa.

Feline Idiopathic Cystitis

Feline idiopathic cystitis shares with otitis externa the pattern of sterile inflammation driven by stress, environmental factors, and disruption of normal tissue defences, though the target organ and clinical signs differ; both conditions can reflect broader stress-related illness in cats.

Feline Asthma

Feline asthma and otitis externa both involve chronic inflammation in mucosal tissues and can occur in cats with heightened immune reactivity; in some cases, cats with allergic or inflammatory tendencies may develop problems at multiple body sites over time.

Once the immediate inflammation has settled, it can be useful to reflect on whether this was an isolated episode or part of a broader pattern—whether the same ear has been troublesome before, whether the other ear has shown similar signs, or whether skin or digestive changes have appeared around the same time. Cats with recurrent ear problems sometimes turn out to have allergies or other immune-mediated conditions that benefit from a wider look at their health. The pillar material on immune and inflammatory health explores some of these connections in more detail.

Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS