Canine Ear Infection
Canine ear infection (otitis externa) is one of the most common dog ear problems. It can be caused by bacteria, yeast, allergies, and more. This page looks at outer ear infections in dogs, their symptoms, causes, and treatment.

A dog’s ear canal is L-shaped with a vertical and a horizontal component, making it easy for dirt and debris to be trapped in the canal, so it is much more easier for dogs to develop ear infections.

Dogs with long, floppy ears are especially prone to ear infections due to a lack of air circulation in the ears, making it an ideal breeding ground for bacteria.

About 80% of infections occur in dogs with long, floppy ears.

Canine ear infection can be just limited to the ear canal (outer ear infection), or it can involve the eardrum and the cavity of the middle ear (middle ear infection), or even the inner ear (inner ear infection).

This page looks at outer ear infection in dogs.

Please also visit this page for some simple but effective home remedies for treating mild ear infections.

Causes of Canine Ear Infection

There are numerous reasons for dogs to develop ear infections. The most common ones are:


Dogs with allergic skin diseases, such as canine atopy and food allergies, are predisposed to ear infections which are part of the allergic responses.


Dogs with primary or secondary seborrhea usually have oily, yellowish ear wax buildup which can result in bacterial ear infection.


Numerous types of bacteria cause ear infections in dogs, especially dogs with a compromised immune system, or if there is a change in the ear environment due to allergies, hormone abnormalities, or moisture.

In acute form of bacterial ear infections, the ear discharge is moist and light brown. Chronic bacterial ear infections in dogs usually result in a yellow or greenish discharge.


Dog ear yeast infections may be the result of antibiotic treatment of bacterial ear infections. Yeast infections also occur in dogs with atopic dermatitis, food allergies, and seborrhea.

The ear discharge is usually brown and waxy, with a rancid smell. Alternatively, the ear is red and inflamed with minimal discharge.

Ear Mites

Although mites are less common in dogs than in cats, some dogs are hypersensitive to the mites. As a result, they feel intense itch and scratch their ear incessantly, traumatizing the ear and causing infection.

Foreign Objects

Foreign bodies such as foxtails, grass seeds, etc. can sometimes gain access into the ear canal, irritating the dog’s ear. After much scratching and rubbing by the dog, ear infection occurs.

Breed Predisposition

Some breeds (such as the Shar-Peis) have narrow ear canals, while other breeds (such as the Poodles and Schnauzers) have a lot of hair deep in the canal. As a result, these breeds of dogs are predisposed to canine ear infection.

Other Causes

Sometimes dog parents may inadvertently cause canine ear infection in their dogs by, for example, using Q-tips to clean their dog’s ears, or by allowing water to get into the ears during bathing or swimming, or through improper cleaning and grooming of the ears.

Symptoms of Canine Ear Infection

If your dog has an ear infection, he will scratch the affected ear incessantly and rub it against furniture or on the floor.

There will be a lot of violent head-shaking as well.

The affected ear is painful so your dog will tilt his head to the painful side, and cry out if the ear is touched. Because of the pain, he may also drool excessively.

If you examine your dog’s affected ear, you will notice that there is redness and swelling of the skin folds.

Depending on the cause of the ear infection, you may also find a smelly, waxy or pus-like discharge from the ear.

Diagnosis of Canine Ear Infection

As you can see above, there are many possible causes of canine ear infection.

Also, a case of outer ear infection, if not properly treated, can progress to the middle ear. Middle ear infection is more serious and can lead to hearing loss. It is therefore important to take your dog to a vet for a proper diagnosis if you suspect ear infection.

Diagnosis involves the use of an otoscope to examine the deep portions of the ear canal. Prior to that, the ear may have to be cleaned if it is filled with wax and debris. This is often done while the dog is under sedation.

The vet will also make sure that the eardrums are intact as it is unsafe to apply ear medications if the drums are perforated.

He will also check to see if there are any foreign bodies or tumors that may be causing the problem.

Specimens of the waxy substance in the ear are taken and examined under the microscope to check for the presence of bacteria, yeast, and mites.

Treatment of Canine Ear Infection

The first line of treatment of canine ear infection, no matter the cause, is to have a professional cleaning and drying of the ear canals.

This serves two purposes. First, a clean ear is a less favorable environment for bacteria to thrive. Second, medication cannot penetrate the wax and debris in a dirty ear.

Additional treatment of ear infections in dogs depends of course on the underlying cause.

Usually it involves medicating the ear with a prescription ear medication at home, as well as medications for the underlying problem. For example, antibiotics for a bacterial infection, or anti-fungal medication for a yeast infection.

Keep Your Dog’s Ears Clean

Prevention is better than cure. Check your dog’s ears regularly and keep them clean (especially if your dog’s ears are long and floppy).