Ear infections and otitis in dogs and cats: signs and treatment

What is otitis externa in dogs?

Otitis externa is inflammation of a dog’s outer ear canal and may also involve the visible ear flap.

It can be a short-lived episode or become persistent or recurrent. The term describes where the inflammation is, rather than naming one single cause, so the reason behind it still needs to be identified. [1]

Is otitis externa always an ear infection?

No. Otitis externa means the ear canal is inflamed; bacteria or yeast may be involved, but infection is not present in every case.

An allergy, parasite, foreign body or another primary problem can start the inflammation. Microbial overgrowth can then appear as a secondary complication, which is why treating an ‘infection’ alone may not prevent another flare. [2]

Can otitis externa affect just one ear?

Yes. Otitis externa can affect one ear or both ears, and the severity may differ between them.

The pattern can help a vet think about possible causes. Allergic ear disease often affects both ears, while a sudden problem confined to one ear can make a local cause, such as a foreign body or growth, more important to investigate. [3]

What are the signs of otitis externa in a dog?

Common signs include scratching at the ears, head shaking, redness, pain and waxy or other discharge from the ear canal.

Some dogs also rub their face, hold an ear differently or lose hair around the ear through repeated scratching. Smell, crusting or erosions can appear when secondary infection is present.

Eye irritation can also accompany chronic ear problems when a dog repeatedly rubs its face or irritates the surrounding skin. [2]

Is otitis externa painful for dogs?

It can be. An inflamed ear canal may be painful as well as itchy, and chronic disease can make handling or treatment increasingly distressing.

Pain may show as flinching, pulling away, crying, guarding the head or reluctance to have the ear touched. A dog that suddenly resists familiar handling may be communicating discomfort rather than behaving badly. [4]

Why does my dog’s ear smell bad?

A strong or unusual ear smell can accompany discharge and secondary microbial overgrowth in an inflamed ear.

Smell alone cannot show whether yeast, bacteria or another problem is present, and a normal-looking outer flap does not reveal the whole canal. Otoscopy and ear cytology provide more useful information than odour or discharge colour alone. [2]

Can an ear problem make a dog shake their head?

Yes. Head shaking, ear scratching and rubbing the face or head are common ways ear itch or discomfort can appear.

These signs are not unique to otitis externa: a foreign body, parasite, injury or deeper ear disease can look similar. The ear needs examining to locate the problem and assess how far it extends. [2]

When can an ear problem be more than otitis externa?

Any of the following signs, especially in combination, calls for prompt veterinary attention: a head tilt, loss of balance, unusual eye movements, facial changes, hearing loss or pain when opening the mouth. They can suggest middle- or inner-ear involvement.

These signs warrant prompt veterinary assessment because they can reflect disease beyond the outer canal. Severe pain, marked swelling or a dog that seems systemically unwell also deserves timely attention, even without obvious discharge. [2]

Why do my dog’s ear infections keep coming back?

Recurring ear infections usually mean that an underlying cause or a factor sustaining inflammation has not yet been fully controlled.

A complete approach considers the primary trigger, secondary microbial overgrowth, features that make the ear vulnerable and chronic canal changes. Repeatedly treating each flare without this wider investigation can allow the cycle to continue.

Recurrent or resistant bacterial infections are an important concern in chronic ear disease and need to be considered in the veterinary investigation. [4]

Can allergies cause recurring ear problems in dogs?

Yes. Allergic skin disease is a common underlying cause of recurrent otitis externa and can sometimes show up mainly as ear trouble.

The rest of the skin may also be itchy, but a dog does not need widespread skin lesions for allergy to remain possible. Controlling secondary infection does not by itself control the allergic inflammation behind repeated flares. [2]

Can a grass seed or other foreign body cause an ear problem?

Yes. A foreign body in the ear canal can directly trigger inflammation and may be one reason an ear becomes suddenly uncomfortable.

The object may sit beyond what is visible from outside, and inflammation or discharge can obscure it. An otoscopic examination lets the vet inspect the canal and decide whether safer or more detailed examination is needed. [2]

Can swimming or moisture contribute to otitis externa?

Moisture can change the ear-canal environment and make otitis externa more likely in a dog that is already susceptible.

Swimming or bathing is therefore a possible contributing factor rather than a complete explanation for every episode. Allergic inflammation, ear shape, excess wax, chronic tissue changes and secondary overgrowth may also be involved. [1]

Do floppy ears cause ear infections in dogs?

Floppy or dropped ears can increase susceptibility to otitis externa, but ear shape is not a diagnosis or a complete cause on its own.

Many dogs with dropped ears remain healthy, while dogs with upright ears can still develop otitis. Breed, allergy, moisture, wax production and chronic canal changes all help determine an individual dog’s risk. [5]

Are bacteria and yeast always the original cause of otitis externa?

No. Bacteria and yeast commonly overgrow after the ear canal has already become inflamed or otherwise abnormal.

This distinction matters in recurrent disease: reducing microbial overgrowth can settle a flare, but allergy, a foreign body, a mass or another primary problem may still be driving the inflammation underneath. [4]

Can ear mites cause otitis externa?

Yes. Ear mites and other parasites can directly cause inflammation of the outer ear, particularly in cats and younger animals.

Dark debris can raise suspicion but cannot confirm mites by appearance alone. A veterinary ear examination may include a mineral-oil sample to look for mites alongside cytology for secondary bacteria or yeast. [2]

How does a vet check a dog for otitis externa?

A vet examines the ear flap and surrounding skin, feels the canal, looks inside with an otoscope and usually examines material from the ear under a microscope.

These steps answer different questions: the pet's response to examination may indicate pain or discomfort, otoscopy looks for discharge, foreign material and the eardrum, while cytology identifies the cells and microorganisms present. Discharge or thickening of the canal can prevent the vet from seeing the whole canal or eardrum at the first examination. [1]

Why does a vet swab an inflamed ear?

Ear cytology lets the veterinary team look for yeast, different bacterial shapes and inflammatory cells in material from the canal.

The result helps distinguish inflammation from secondary microbial overgrowth and guides the choice of topical treatment. Repeating cytology can also show whether the microorganisms have cleared, even if the ear looks better from outside. [2]

Why does the vet need to look at the eardrum?

The eardrum helps separate the outer ear canal from the middle ear, so its condition affects both diagnosis and which products can be used safely.

Heavy discharge, swelling or pain can make it difficult to see at the first visit. If the membrane may be damaged, the vet has to consider middle-ear involvement and avoid substances that could harm deeper structures. [2]

When might a vet culture bacteria from a dog’s ear?

A bacterial culture may be considered when otitis is severe, recurrent, associated with rod-shaped bacteria or not responding as expected.

Cytology and culture answer different questions: cytology shows what is present in the ear at the appointment, while culture identifies cultivable bacteria and their laboratory susceptibility. The result still has to be interpreted in the clinical context. [1]

Why does the vet check the rest of the skin for an ear problem?

The ear canal is lined by skin, and recurring otitis can be one part of an allergic or other dermatological condition.

Looking between the toes, around the face, under the body and across the coat may reveal a wider pattern of itching or inflammation. An ear-only presentation does not rule allergy out, but the full pattern helps guide investigation. [2]

Why can two dogs with otitis externa need different treatment?

Otitis externa has different causes, microorganisms, degrees of inflammation and levels of canal damage, so one product or plan does not fit every dog.

The veterinary plan is informed by examination, otoscopy, cytology and the condition of the eardrum. It may need to address pain and inflammation, secondary overgrowth and the underlying trigger as separate parts of the same problem. [2]

Why might ear cleaning be part of veterinary treatment?

Cleaning can remove wax, discharge and debris that block examination or prevent a prescribed topical treatment from reaching the canal lining.

The cleaner and technique need to match the type of material, the degree of pain and the condition of the eardrum. A painful, narrowed or heavily blocked canal may require in-clinic care rather than routine handling at home.

Some bacterial infections need specific cleaning as part of veterinary treatment; care at home may not be sufficient. [6]

Is any ear cleaner safe for a dog with a sore ear?

No. Ear cleaners differ in their ingredients and effects, and some can irritate inflamed tissue or be unsafe if the eardrum is damaged.

A vet can assess the canal and recommend whether cleaning is appropriate, which product suits the discharge and whether home cleaning is comfortable enough for the dog. More cleaning is not automatically better for an already painful ear. [6]

Can old ear drops be reused for a new flare?

Reusing an old ear product without a new assessment can miss a changed cause, a different microorganism or damage to the eardrum.

A familiar-looking flare may not be the same problem as before. Some products can irritate or harm deeper ear structures when the eardrum is not intact, while unnecessary antimicrobials can add selection pressure for resistance.

Do not reuse old or out-of-date ear medicines unless your vet specifically directs you to do so. [2]

Why does a dog’s ear need checking again after treatment?

An ear can look and feel better before inflammation or microbial overgrowth has fully resolved, so a follow-up examination helps confirm the outcome.

The vet may repeat palpation, otoscopy and cytology, then decide whether the plan can stop, change or move into longer-term control. Confirming resolution also makes a later recurrence easier to interpret. [1]

Can recurring otitis externa need long-term management?

Yes. When allergy or another ongoing condition drives recurrent otitis, long-term management may be needed after the current flare has settled.

The aim is to maintain a comfortable, healthy canal and reduce future flares, rather than repeatedly reacting only when infection returns. The maintenance approach depends on the individual trigger, ear changes and response to earlier care.

Some difficult or resistant bacterial infections can recur during allergic flares, stress, immune suppression or skin trauma. Previous infection and treatment history is therefore important when planning ongoing care. [2]

What can happen if otitis externa becomes chronic?

Repeated inflammation can thicken and narrow the ear canal, increase wax and discharge, and make the ear progressively firmer, more painful and harder to treat.

Advanced changes can include tissue overgrowth, scarring, mineralisation and damage to the eardrum. These changes can sustain further inflammation and infection even when the original trigger has been recognised. [6]

Can severe chronic ear disease require surgery?

Yes. Surgery may be considered when irreversible canal changes leave a dog in ongoing pain or prevent medical management from controlling the disease.

This is generally an end-stage decision made after detailed assessment, often with imaging and specialist input. Earlier investigation of recurring flares aims to control the underlying causes before the canal reaches that point. [4]

Can cats develop chronic otitis?

Yes. Chronic otitis is less common in cats than in dogs, but it can still be painful, persistent and difficult to manage.

Feline cases can involve ear mites, allergy, inflammatory polyps, masses, unusual inflammatory disorders and secondary infection. A structured examination matters because focusing on infection alone can leave the primary problem untreated. [7]

Why does a one-sided ear problem matter in a cat?

Persistent otitis affecting only one ear can make a local problem, such as an inflammatory polyp or mass, more important to investigate in a cat.

That does not mean every one-sided problem is a growth; foreign material, infection and other causes remain possible. Otoscopy, cytology and sometimes imaging help the vet determine what is happening beyond the visible opening. [7]