What does a dog ear infection look like?

Ear infections are one of those things that make a dog uncomfortable long before they make an owner worried. Recognizing the look and the behavior that go with an infected ear can shorten a dog’s misery, speed effective treatment, and reduce the chance the problem becomes chronic. I typically see owners notice ear issues after repeated head shaking, sudden rubbing at the ear, or when a bath or swim reveals unexpected crust or smell. Knowing who’s at higher risk and what to do first matters because early, appropriate care often prevents pain, spread deeper into the ear, and expensive, prolonged therapy.

Why early detection matters: spare your dog pain and potential hearing loss

Some dogs are simply more likely to develop ear problems. Breeds with long, floppy ears that limit airflow—Cocker Spaniels, Basset Hounds, and some spaniels—often trap moisture and debris. Dense, hairy ear canals, commonly found in Poodles and some terriers, can act the same way. Young dogs can pick up ear mites more easily, while older animals may suffer more from chronic inflammatory conditions or endocrine problems that change skin health. Lifestyle matters too: dogs that swim frequently, work in wet fields, or live in humid climates have greater exposure to moisture and foreign material.

Typical owner scenarios include noticing a sudden, dark discharge after a bath, seeing your dog paw at an ear after a romp in tall grass, or smelling a persistent bad odor when you lean in to pet them. The benefits of early detection are concrete: less pain, shorter treatment courses, fewer secondary infections, and a lower chance of permanent changes to the ear canal like scarring or narrowing that make infections recurrent.

How an infected ear typically looks — a quick visual guide

A normal canine ear flap and canal look pale pink, clean, and have minimal waxy material. The skin should not be red or swollen, and there should be no strong odor. An ear that may be infected often looks different at a glance: the skin inside the ear is reddened, the canal may appear swollen or partly closed, and you may see discharge. Discharge colors and textures can help suggest what’s happening: brown or black waxy material can be associated with yeast or trapped debris; yellow or greenish discharge is more likely to suggest bacterial infection or pus; very dark crumbly material sometimes points to mites. A greasy, darker buildup can be yeast overgrowth.

Behavioural cues are often the first sign owners notice: frequent head shaking, scratching or rubbing the ear with a paw, holding the head tipped to one side, or sensitivity when the ear is touched. Some dogs suddenly stop wanting their head petted. If the ear is painful, a dog may resist having you look closely or may yelp if you touch around the base of the ear or pull the ear flap up.

Inside a dog’s ear: key anatomy and how infections develop

The external ear begins with the pinna—the visible flap—and continues into a vertical canal that becomes a horizontal canal leading to the eardrum. The middle ear and inner ear lie beyond the eardrum and are involved in hearing and balance. The part most commonly affected by routine infections is the external canal. Its shape and limited airflow, as well as normal wax production, are protective in small amounts but can allow moisture, debris, and microorganisms to accumulate if conditions change.

Several types of microorganisms may be involved. Yeast organisms such as Malassezia species are frequent contributors and often create a greasy, sweet or musty smell; bacterial species, including Staphylococcus and Pseudomonas, may produce pus-like discharge and a stronger foul odor; and ear mites (Otodectes cynotis) can create dark, coffee-ground debris, especially in puppies or multi-pet households. In many cases two or more problems coexist—yeast overgrowth may follow a bacterial infection, and underlying allergies can make both worse.

Inflammation itself produces many of the signs: swollen skin narrows the canal, making drainage harder and pain worse, and inflamed glands can produce more secretions. Tissue heat and decreased local immune function can favor growth of bacteria and yeast, so what starts as a small irritation may become a self-perpetuating cycle unless the underlying drivers are addressed.

Top causes and who’s most at risk for ear infections

Floppy-eared breeds are prone because air exchange is reduced; hairy canals become blocked more easily. Frequent moisture exposure—after swimming, bathing, or during rainy seasons—creates an environment where yeast and bacteria thrive. Allergies, whether environmental (atopy) or food-related, are a very common underlying cause of recurrent ear infections because they change the skin’s barrier and immune responses. Foreign bodies like grass awns can lodge in the canal and trigger a secondary infection. Systemic health issues such as hypothyroidism or immune suppression from medications may also increase susceptibility.

Understanding these triggers helps target prevention: addressing allergies or trimming canal hair, drying ears after water exposure, and checking for foreign bodies after outdoor play can reduce recurrence. If a dog has frequent infections despite these measures, it’s likely linked to an underlying skin condition that needs veterinary assessment rather than repeated at-home treatment alone.

When to worry: red flags and emergency signs

Not every ear problem is an emergency, but some signs require immediate veterinary care. Severe swelling, marked heat around the ear, or obvious intense pain suggest a rapidly progressing infection or abscess. Blood or persistent foul odor, especially with thick pus, raises concern for aggressive bacterial infection. Any neurological signs—such as a head tilt, loss of balance, sudden circling, or facial paralysis on one side—may indicate that the infection has moved to the middle or inner ear and needs urgent attention.

Systemic signs like fever, loss of appetite, lethargy, or if the dog becomes generally unwell, also indicate the infection may be more than local. Rapid worsening over hours or failure to respond to previously effective treatment are other reasons to contact your veterinarian quickly.

First-response checklist for owners: what to do immediately

When you first suspect an infection, stay calm and follow simple steps that keep the ear safe and help your veterinarian make a prompt diagnosis. Safely restrain the dog so you can inspect the ear without creating more stress—ask a helper to gently hold the body while you lift the ear flap. Look and smell from a short distance; a bad smell close to the ear is informative. If the dog allows, lift the ear flap and look for redness, swelling, discharge, or foreign bodies.

1. Do not insert cotton swabs or any object deep into the canal—this can push material toward the eardrum or cause injury.
2. Do not pour unprescribed fluids into the ear if you suspect a perforated eardrum; that can cause middle- or inner-ear damage.
3. Take clear photos of both ears from multiple angles and note when the signs began, any recent baths, swims, or new foods, and anything you’ve tried at home.

Contact your veterinarian if the dog is in obvious pain, if you see blood, large amounts of pus, or neurologic signs, or if you’re unsure. If the situation is less urgent and your vet is available, send the photos and a timeline—this helps the clinician advise whether an in-person exam is needed that day or whether a scheduled appointment will do.

At-home care and prevention: daily routines to keep ears healthy

Routine care can greatly reduce recurrence. After swimming or bathing, gently dry the ear with a soft towel and, if recommended by your vet, use a dry cotton ball inside the ear opening (not deep) to absorb moisture. Regular ear checks—lifting the flap and looking once a week for at-risk dogs—catch early changes. If a vet prescribes a routine cleaner, use it as directed; over-cleaning can strip protective oils and make problems worse.

Managing underlying issues is key. If allergies are suspected, work with your veterinarian to evaluate and treat them; controlling atopic disease or food sensitivities often reduces ear infection frequency. For dogs with heavy hair inside the canal, regular grooming or careful plucking by a trained groomer or vet may be helpful. Schedule follow-up checks when your vet recommends them—ear infections sometimes require rechecks to confirm resolution and prevent relapse.

Vet-recommended supplies and tools for treating and preventing infections

Having the right supplies on hand makes safe care simpler and avoids harmful home remedies. Veterinary-formulated ear cleaners can be helpful when used under guidance; they are formulated to dry and restore pH without irritating sensitive skin. Avoid homemade mixtures unless instructed by your vet, because some ingredients can burn or penetrate a damaged eardrum.

• Soft gauze pads or cotton balls for gentle cleaning of the visible ear (never insert deep into the canal)
• Veterinary ear cleanser recommended by your veterinarian
• Prescription ear drops or oral medications only as directed by your vet
• Elizabethan collar or soft cone to prevent self-trauma while healing
• Ear-drying products for dogs that swim frequently, if recommended

Keep all medications out of reach, follow dosing exactly, and finish the prescribed course unless instructed otherwise. If the ear worsens on treatment, stop and contact your veterinarian rather than changing medications yourself.

Sources and further reading

• Merck Veterinary Manual: “Otitis Externa in Dogs” — Merck Veterinary Manual, section on canine ear infections.
• World Small Animal Veterinary Association (WSAVA) Global Ear Care Guidelines — clinical guidance on diagnosis and treatment of otitis externa.
• AAHA (American Animal Hospital Association): Canine Otitis Externa Guidelines — clinical recommendations for managing ear infections in dogs.
• Miller, W.H., Griffin, C.E., and Campbell, K.L., Muller and Kirk’s Small Animal Dermatology — textbook chapters on otitis and ear disease.
• Plumb’s Veterinary Drug Handbook — for information on common ear medications and dosing considerations.