Otitis is inflammation of the ear, and it’s one of the most common reasons dogs end up at the veterinarian. It can affect the outer ear canal, the middle ear, or (rarely) the inner ear, and it ranges from a mild, itchy nuisance to a painful condition that causes lasting damage if left untreated. Most cases start in the outer ear canal and are driven by an underlying issue like allergies, moisture, or the shape of the dog’s ear itself.
Three Types Based on Location
Otitis is classified by which part of the ear is inflamed. Otitis externa, the most common form, affects the outer ear canal. Otitis media is inflammation of the middle ear, including the eardrum and the tiny bones behind it. Otitis interna involves the deepest structures: the cochlea (responsible for hearing) and the semicircular canals (responsible for balance).
In most dogs, the progression follows a predictable path. Otitis externa that goes untreated or keeps coming back can eventually spread inward to become otitis media. Untreated otitis media can then reach the inner ear. Middle ear infections are less common than outer ear infections, and inner ear infections are rare. When otitis media does develop, it’s often an extension of chronic otitis externa rather than something that starts on its own.
Why Dogs Are Prone to Ear Infections
A dog’s ear canal is fundamentally different from a human’s. Where yours is short and relatively straight, a dog’s ear canal is long, narrow, and makes an almost 90-degree bend before reaching the deeper structures. That L-shape means moisture, wax, and debris can easily get trapped and have a hard time draining out. It creates a warm, dark environment where yeast and bacteria thrive.
Certain physical traits make things worse. Dogs with heavy, floppy ears have reduced airflow into the canal. Dogs with lots of hair in and around the ear opening face the same problem. And some breeds, like Shar-Peis, have unusually narrow ear canals where even a small amount of debris can cause a blockage. Good airflow is one of the most important factors in maintaining a healthy ear, and many dogs are built in a way that works against them.
Breeds at Higher Risk
Cocker Spaniels top most lists because of their combination of heavy, floppy ears and thick hair. Labrador Retrievers are frequent swimmers, and that repeated moisture exposure gives yeast and bacteria exactly what they need to multiply. Poodles have very hairy ear canals, which can trap infectious material once a problem starts. Shar-Peis and other wrinkly breeds often have narrow canals that clog easily. Pit Bulls are prone to skin allergies that frequently extend to the ears.
That said, any dog can develop otitis. Allergic dogs of any breed are especially vulnerable, because the allergic response itself triggers overgrowth of the yeast and bacteria that normally live in the ear in small, harmless numbers.
What Actually Causes It
The single most common trigger for otitis externa is allergic skin disease, including environmental allergies and food sensitivities. About 55% of dogs with allergic skin disease develop ear infections, and in some dogs, recurring ear problems are the only visible sign of an allergy. The ear canal is lined with skin, so any condition that affects the skin can affect the ears.
Other primary causes include ear mites (especially in puppies), foreign bodies like grass seeds that lodge in the canal, and hormonal conditions that change the ear’s environment. Once the ear is inflamed, the organisms that normally live there in low numbers can explode in population. A yeast called Malassezia pachydermatis is present in 15% to 50% of healthy dog ears but can be found in up to 83% of infected ears. Bacteria, particularly staph and pseudomonas species, often join in or take over.
Signs to Watch For
The hallmark signs of otitis externa are head shaking, scratching or pawing at the affected ear, and a foul smell. You may notice redness and swelling of the ear flap, a dark or yellowish discharge, or scaly, crusty skin around the ear opening. Some dogs rub the side of their head along furniture or the floor. The ear can be painful, itchy, or both.
When infection reaches the middle ear, the signs often overlap with outer ear infection but may also include more subtle neurological changes. Drooping of the eyelid, a smaller pupil on the affected side, or facial nerve problems (like a drooping lip) can help distinguish middle ear involvement from a simple external infection. Inner ear infections, though rare, typically cause a head tilt, loss of balance, circling, or stumbling.
Chronic, long-standing otitis can permanently change the ear canal. You might notice thickened, deformed ear flaps, abnormal growths inside the canal, or persistent head shaking even between flare-ups.
How Veterinarians Diagnose It
Your vet will start by looking into the ear canal with an otoscope, a lighted cone that lets them see the canal walls and, if possible, the eardrum. They’re checking for redness, swelling, discharge, foreign objects, masses, and whether the eardrum is intact.
The most informative step is ear cytology. A small swab of ear discharge is spread on a glass slide, stained, and examined under a microscope. This tells the vet whether the infection is driven by yeast, bacteria, or both, and how severe the overgrowth is. Cytology also reveals whether inflammatory cells are present, which helps guide treatment decisions. It’s a quick, inexpensive test that makes a real difference in choosing the right medication, and it’s often repeated during follow-up visits to confirm the infection is actually resolving.
Treatment Approach
Treatment targets three things at once: killing the infection, reducing inflammation, and addressing whatever caused the problem in the first place. Most ear medications prescribed by vets combine an antibacterial ingredient, an antifungal ingredient, and a steroid to bring down swelling and pain. Some are applied daily at home, while others are single-dose treatments applied in the clinic that last for weeks.
Before any medication goes in, the ear usually needs a thorough cleaning. For moderate to severe cases, your vet may do this in the office, sometimes under sedation, to flush out debris without hurting a painful ear. Mild cases can often be managed with at-home cleaning followed by prescribed drops.
The underlying cause matters just as much as the immediate infection. If allergies are driving recurrent otitis, treating the ears alone will only buy time between flare-ups. Your vet may recommend allergy testing, dietary trials to rule out food sensitivities, or long-term allergy management. Without addressing the root cause, many dogs cycle through ear infections repeatedly.
Complications of Untreated Otitis
One of the most common complications is an aural hematoma, a blood-filled swelling on the ear flap. It happens when a dog shakes its head or scratches so forcefully that blood vessels inside the ear flap rupture. The ear puffs up like a pillow. Treatment ranges from draining the fluid with a needle to surgery, where the vet makes an incision on the underside of the ear flap to drain it and then places sutures to prevent the space from refilling. Aural hematomas are particularly common in dogs with chronic otitis externa.
Chronic untreated otitis can also cause the ear canal to narrow and thicken permanently, eventually becoming so scarred that topical medications can’t reach the deeper canal. In severe end-stage cases, surgery to remove the ear canal entirely may be the only option to relieve pain.
Cleaning and Prevention at Home
How often you clean your dog’s ears depends on the dog. For a healthy dog with normal, upright ears, you only need to clean when you notice visible dirt or debris. Overcleaning can actually irritate the ear and disrupt its natural defenses. Dogs with a history of allergies, recurrent infections, or floppy ears may benefit from cleaning every one to two weeks. During active treatment of an infection, your vet may recommend daily cleaning initially.
The technique matters more than the frequency. Use a veterinary ear cleaning solution, never alcohol or hydrogen peroxide, which can sting and damage tissue. Gently fill or saturate the canal, then massage the base of the ear for several seconds to loosen debris. Let your dog shake (they will), then use cotton pads or cotton balls to wipe away what comes out. Only go as deep as your finger fits comfortably, about one knuckle in. Never use cotton swabs, which can push debris deeper into that L-shaped canal. And don’t force the bottle tip into the ear and squeeze hard, as the resulting pressure could rupture the eardrum.
If your dog yelps or pulls away during cleaning, stop. Pain during ear cleaning usually means there’s an active infection or injury that needs veterinary attention before you continue at home.