A Guide to Canine Ear Infections

Ear infections are one of the most common health problems dogs face. Here's what you should know:

What is an ear infection?

Infection of the outer ear, or otitis externa, indicates chronic inflammation of the external ear canal. This type of infection is often caused by bacteria or yeast. Infection of the middle or inner ear can also occur.

What are the symptoms?

Ear infections are typically very uncomfortable, though some dogs may not show any outward signs of a problem. Regardless, all infections must be treated as thickening, scarring, and resistance can develop.

Signs of an ear infection include:

  • Head shaking or tilting
  • Scratching at the ears
  • Redness and inflammation
  • Black or yellow discharge
  • Offensive odor

Does my dog need an exam?

Yes.

The primary reason for this is that several kinds of bacteria and at least one type of fungus can cause an ear infection. Without knowing the kind of infection present, we cannot determine the best drug to treat it. If the infection is caused by a foreign body, such as a foxtail or tumor in the ear canal, treatment with medication alone will not resolve the problem.

The dog must also be examined to ensure the eardrum is intact. Middle ear or inner ear infections can result if the eardrum is ruptured. The veterinarian makes this determination and must be done in the hospital.

Additionally, it is essential to note that many ear infections have an underlying cause, like allergies or hypothyroidism. Unless the underlying cause is also treated, the infections will become recurrent. The only way to know if an infection has been resolved completely is by looking in the ear and performing a cytology (cell study) to look for persistent organisms.

How do you determine which drug to use for treatment?

First, the ear is examined with an otoscope, which provides magnification and light and allows us to look into the canal. From here, we can determine whether the eardrum is intact or if there is any foreign material in the canal. When a dog is in extreme pain, the exam should be done with sedation or under anesthesia. Some dogs also have such a heavy buildup of debris that sedation is needed to clean the canal and examine it thoroughly.

An ear cytology, or the examination of a sample of the material from the ear canal, is used to determine which organisms are causing the infection. Studying the material under the microscope is critical in helping the veterinarian choose the proper medication to treat the ear.

How are ear infections treated?

The results of the otoscopic examination and ear cytology tell us what to do. Sometimes the cytology reveals the presence of more than one type of infection (i.e., bacterial and fungal or two different kinds of bacteria); this situation usually requires the use of multiple medications or a broad-spectrum medication. We will sometimes want to culture the debris based on the cytology results.

The dog will be sedated for removal if a foreign body or tick is lodged in the ear canal.

If an underlying cause of infection is found, it must be diagnosed and treated. If treatment of the underlying disease is not possible, the dog is less likely to have a favorable response to treatment. The dog may also respond temporarily before a relapse of the infection occurs (usually when the medication is discontinued).

Why is a recheck exam so important?

A recheck exam will be needed before the treatment process is completed. This exam is very important because the ears may need to be treated longer. While the dog's symptoms may have resolved because they feel so much better, an infection may still be present. It is impossible to determine whether the infection has cleared without rechecking the ears.

For chronic infections, routine care at home is key to keeping the problem under control.

How do I treat my dog at home?

It is crucial to get your dog's medication into the horizontal part of the ear canal. The dog's external ear canal is "L" shaped. The vertical canal connects with the outside of the ear, while the horizontal canal lies deeper in the ear and terminates at the eardrum.

The ear canal may be medicated by following these steps:

  1. Gently pull the earflap straight up and hold it with one hand.
  2. Apply a small amount of medication into the ear canal's vertical part while keeping the earflap elevated.
  3. Hold this position long enough for the medication to run down to the turn between the vertical and horizontal canal.
  4. Put one or two fingers behind the earflap at the base.
  5. Place your thumb on the opposite side of the base.
  6. Massage the ear canal between your finger and thumb.
  7. A squishing sound tells you the medication has gone into the horizontal canal.
  8. Release the earflap and let your dog shake their head.

If the medication contains a wax solvent, debris will be dissolved so it can be shaken out. It is also important to clean your dog's ears regularly. Directions for cleaning the ears are the same as the medication instructions above, except that the ear cleaning solution will need to be wiped out of the canal. 

Call your veterinarian immediately if you suspect your dog has an ear infection. While you can handle the subsequent treatment and cleaning, your veterinarian must make a diagnosis to dispense the proper medication. Don't have one yet? We can help you find a local veterinarian.

Contributing DVM