Signs of otitis, or ear inflammation or infection, in dogs include ear redness, swelling, and odor. Dogs with otitis may shake their heads, scratch their ears, and resist petting because of pain.

Canine Ear Diagram

Types of Otitis

Otitis Externa (OE) is inflammation of the pinna (ear flap) and the “L-shaped” ear canal, with its vertical and horizontal parts. A dog’s long ear canal can make it difficult to clean.

Otitis Media (OM) is inflammation of the middle ear. The middle ear begins at the tympanic membrane (eardrum) and is close to nerves that control balance. Pus from ear infections can get trapped in the middle ear.

Otitis interna (OI) is inflammation of the inner ear, which has small, delicate structures that are important for hearing and balance.

Types of Ear Infections

Many otitis cases also have an infection. Bacterial ear infections are usually caused by Staphylococcus and Pseudomonas bacteria. Fungal ear infections are usually caused by a yeast called Malassezia.

Dog ears normally have Staphylococcus and Malassezia. These bacteria and yeast multiply in number in inflamed and irritated ears, leading to an ear infection. Repeated treatment with antibiotics and antifungals can also cause other bacteria, such as Pseudomonas, to grow in an ear. Pseudomonas ear infections can be difficult to treat because they are resistant to antibiotics.

Causes of Ear Infections

Your dog may be more likely to get ear infections if they have any of the following:

Allergies cause skin inflammation in dogs. Because the ear canal is lined with skin, allergies are a common cause of otitis. Diagnosing and treating your dog’s allergies are an important part of preventing future ear infections.

Some dog breeds' ear shapes may make them more prone to ear infections. Drooping ears or narrow ear canals may help trap moisture and debris deep in the ear.

Foreign bodies, such as grass awns, can get lodged in the ear, migrate through the ear canal, and rupture the eardrum.

Ear injuries can increase your dog’s risk of ear infections. Otic mineralization is a type of damage to the ear canal caused by repeated ear infections over time. Surgery to remove an ear mass can lead to scarring and narrowing of the ear canal.

Diagnosis of Ear Infections

If you suspect your dog may have an ear infection, make an appointment with your veterinarian. Your veterinarian will start by asking about your dog’s medical history. This is because skin and ear infections can be secondary to other health problems.

Your veterinarian will use a tool called an otoscope to look inside your dog’s ear. To diagnose the type of ear infection, your veterinarian will perform ear cytology by collecting a sample from the ear, staining it, and examining it under a microscope. Ear cytology is important because no ear medication works for all types of ear infections. Determining the type of ear infection your dog has will help your veterinarian prescribe the right medications.

Treatment of Ear Infections

Common medications for ear infections include antibiotics, antifungals, steroids, and pain medications. Follow your veterinarian’s instructions for cleaning and treating the ear at home. Do not stop your dog’s ear treatments on your own without checking with your veterinarian.

Your dog will need follow-up visits with your veterinarian after the ear treatment. An ear infection will worsen if the medication is stopped too early. However, using antibiotics and steroids for too long can cause other health issues for your dog. Rechecking ear cytology helps your veterinarian determine if the ear infection is gone and is an important part of your dog’s ear care.

What To Do When Your Dog Has Repeated Ear Infections

Repeated ear infections are a serious health problem for your dog. Dogs can develop permanent damage to the ear canal (otic mineralization) and surrounding bone (osteomyelitis), leading to surgery to remove part of your dog’s ear.

A detailed exam, ear cleaning, and treatment session using a specialized endoscope for the ears may be recommended. This deep ear flush is an important treatment step for some types of ear infections, such as Pseudomonas, because the infection forms a slippery layer of debris called biofilm that blocks medications. 
Ear infections can also spread deep into your dog’s ear. In the veterinary world, veterinary dermatologists are the otologists, or ear specialists, for dogs. 

If your dog has recurrent infections, your veterinarian may recommend referring you to a board-certified veterinary dermatologist. A computed tomography (CT) scan can be used to look through bone and inside the middle ear to diagnose otitis media.