I. Dog Ear Anatomy

A dog’s ears are the same as a person’s ears in that their main function is hearing. Dog ears just do not look like people’s ears. The outside part of the ear is called the pinna. In some dogs it is floppy (like a Basset Hound) and in some dogs it stands up (like a Corgi). The pinna helps to funnel sound into the ear canal. Whereas people have a straight ear canal, the ear canal in the dog is a little “L” shaped. It is made up of the vertical (descending) canal and the horizontal canal. The horizontal canal ends at the eardrum, or tympanic membrane. The eardrum is a transparent membrane that separates the external ear from the middle and inner ear.

II. The Causes of Ear Infections

The most common ear infection in dogs is an infection of the external part of the ear including the horizontal and vertical canals. This type of infection is called otitis externa. Otitis externa in dogs is really only caused by three things:·

• ear mites


• bacteria


• yeast

Ear mite infections are caused by the mite Otodectes cynotis. Ear mite infections are seen more in puppies than adult dogs, but any dog can get ear mites. A dog gets ear mites from other infected dogs. Ear mites can live in the ear and on the head and neck.

Otodectes cynotis mites

The bacterium most commonly involved in ear infections is Staphylococcus and the yeast most commonly seen is Malassezia. Bacterial and yeast infections are more common in dogs than ear mite infections. Even though there are only a few causes of ear infections, many things predispose a dog to getting an ear infection. Some of the most common predisposing factors are:

• Ear canal conformation – Ear canals that are very small or longer than normal retain debris and moisture that can lead to an ear infection.


• Excessive hair in the ear canal – Excess hair in the ear canal can trap water and debris leading to an ear infection.


• Swimming or living in humid areas – Water retained in the horizontal canal after swimming can lead to an ear infection. In humid climates, water from the air may accumulate in the ear canal leading to an ear infection.


• Floppy or folded over pinnae – Pinnae that cover the opening of the vertical canal may result in retention of water and debris which can lead to an ear infection.


• Food allergies – An allergic response to a particular food ingredient can change the environment of the ear canal leading to moisture build-up and an ear infection. Dogs with food allergies may have other skin problems, too.


• Seasonal or Inhalant allergies (atopy) - An allergic response to grass, trees, mold, dust, etc. can change the environment of the ear canal leading to moisture build-up and an ear infection. Dogs with seasonal allergies will usually have other skin problems, too.


• Systemic Diseases – Some diseases of the endocrine system, such as hypothyroidism, change the environment of the skin and decrease the ability of the immune system to fight off infection. The combination of these things can lead to ear infections.


• A growth or foreign object in the ear – A growth or foreign object in the ear can trap water and debris in the ear canal leading to an infection.


• Cleaning the ears too much and leaving water or cleanser in the ears may also predispose a dog to getting ear infections.

III. What to Watch for at Home –Symptoms of Ear Infections

All ear infections, regardless of the cause, may have the same symptoms. Some symptoms to watch for at home that might mean your dog has an ear infection are:·

• Shaking the head


• Scratching at the head or ears


• Rubbing the head and ears on the ground


• Redness or irritation of the ear canal


• Discharge coming from the ears


• Brown or yellowish discharge in the ears


• Bad smell coming from the ears


• Pain when the head or ears are touched or petted

IV. Visiting the Veterinarian - Figuring out Why Your Dog has an Ear Infection

When you first notice symptoms of an ear infection, it is important to take your dog to see your veterinarian. You should be careful about putting anything into your dog’s ears before a veterinary examination. If your dog has a ruptured eardrum, putting anything in its ears could lead to more severe symptoms including a head tilt, walking in circles, or other neurologic symptoms. Your veterinarian will look carefully to make sure your dog has an intact eardrum. He or she will likely take a sample of the discharge in your dog’s ears to look at under the microscope. This will show whether bacteria, yeast, or ear mites are involved in the infection. If this is the first time that your dog has had an ear infection, this may be the only test necessary before treatment is prescribed.

For dogs that get repeated ear infections or have infections that will not go away with treatment, it is important to find the underlying cause of their problems. Some things are easy to figure out just from a physical examination. If a dog has a lot of hair in its ears, floppy pinnae, or small ear canals, a visual examination will show this. Tumors and foreign objects in the ear can usually be seen during a physical examination, too. Careful questioning will reveal whether or not a dog swims a lot or spends a lot of time in moist or humid areas. If all of these problems have been ruled out, it is time to do further diagnostic testing.

Food allergies are usually ruled out with a food trial. During a food trial, a special hypoallergenic food is fed for a period of 8-12 weeks. The dog is monitored during this time to see if its symptoms improve.

Atopy can be ruled out with either blood tests or with skin testing, similar to allergy testing in people. These tests will usually tell specifically what things a dog is allergic to.

Hypothyroidism and other endocrine diseases affecting the skin are usually diagnosed through a series of one or more blood tests which test the function of a particular endocrine organ. Usually dogs with endocrine disorders will have other symptoms besides ear infections that will lead the veterinarian to suspect another problem.

VI. Treatment of Ear Infections

Addressing the underlying reason that your dog has an ear infection is a very important part of controlling and treating ear infections. For dogs with food allergies, it is important to avoid those foods that they are allergic to. These dogs will need to eat specially formulated food for the rest of their lives. Dogs with atopy will probably be on a combination of medications to control their symptoms for the rest of their lives. This usually consists of a combination of corticosteroids, antihistamines, omega-3 fatty acid supplements and cyclosporine. Periodic treatment of skin and ear infections with antibiotics, antifungals, shampoos and topical rinses is usually necessary also. The course of treatment varies for each dog and depends on how severely allergic they are and how well they respond to therapy. Dogs with endocrine diseases should be treated for those diseases as well as being treated for an ear infection. When the underlying disease is treated, the ear infections are more likely to go away and less likely to come back. Dogs that swim a lot or are in moist environments should have their ears dried on a regular basis. This will help keep moisture from building up in the canal and may keep them from getting as many ear infections. Tumors and foreign bodies in the ear should be removed.

While finding the underlying cause of an ear infection is important, it is important also to treat the ear infection itself. Most ear infections are treated with a combination of topical medication that you put in your dog’s ear and oral medication. While treating an ear infection, it is important to clean a dog’s ears once or twice weekly to prevent buildup of medication and debris in the ear. The ear must be dried well after cleaning. Ear infections are usually treated for at least two weeks but may need to be treated for longer. If an ear infection will not clear up, a culture should be done as well.

VII. Prevention

• Treat any underlying diseases that might be present.


• Dry your dog’s ears out after a bath.


• Dry your dog’s ears out every time it swims.


• Do not put any water or cleanser in your dog’s ears unless you have to and always dry the ears out well afterwards.

Remember: Keeping the ears dry is an important part of treating and preventing ear infections.

Nothing in this article is intended to diagnose or treat your pet and does not replace a visit to your veterinarian for appropriate diagnosis and treatment.