Dog's ear infection can be a difficult problem to resolve

1/29/2012

One of the more common medical problems I see in dogs is a recurring ear infection. Many times people are frustrated to continually battle this issue and worried about the pain and irritation their dog is enduring. Often there are a number of underlying diseases that lead to secondary infections and the problem will repeatedly relapse if you don't address the primary conditions.

Symptoms of an ear infection in dogs usually involve head shaking, scratching, odor, discharge, and swelling in the outer ear. A little knowledge of the anatomy of the canine ear helps understand treatment and why these infections can be difficult to manage.

Dog's ears are divided anatomically into external and a middle/internal ear separated by the eardrum. The external ear canal is significantly longer than a human's and has a 90-degree turn about halfway down. Looking at the ear flap only is about 10 percent of the total structure of the ear. The middle and internal ear canal house the small bones and nerves that make up the hearing apparatus. Most infections in dogs involve the external ear canal, also called otitis externa. Infections are a result of an overgrowth of yeast or bacteria that triggers an inflammatory response that results in the symptoms.

Recurring infections typically stem from a couple of underlying issues. Allergic skin disease creates an environment ripe for yeast to grow. Ears are dark, deep pockets of skin, and if skin disease is present it makes sense that the ears will be susceptible. If the primary allergies are not addressed, the ears will continue to be a problem. These infections can lead to swelling and scarring, and once they establish themselves in the middle or inner ear they will be extremely difficult to clear.

Any infection has the potential to develop resistance from continual exposure to antibiotics. If a bacterial infection has been repeatedly treated and not completely cleared, the remaining bacteria will become resistant to any number of antibiotics. If this is the case, a culture will need to be obtained from the ear and submitted to a lab, which will identify the bacteria and determine what commonly used drugs would be appropriate. This highlights the fact that follow-up visits to confirm the infection is cleared are crucial. I tell people infections are like termites. If you get rid of 95 percent of your termites, you still have termites and they will come back.

If the infection has worked its way down to the middle and inner ear, most common treatments will have trouble reaching the deepest parts of the ear. Oral antibiotics have a difficult time getting to the affected area and topicals will not make it deep enough in the ear. A surgical procedure to open up the eardrum and facilitate drainage may be needed to successfully clear a deep infection in the ear.

Even a seemingly routine ear infection should be fully cleared to avoid many of the problems I have described. What may seem like a simple treatment has the potential to lead to a very difficult disease to manage. Over time the infections will lead to chronic pain and can even change the personality of many dogs.

Questions for Dr. Gary Thompson can be emailed to askthevet@theblade.com or mailed to The Blade, Attn. Ask the Vet, 541 N. Superior St., Toledo, OH 43660. Dr. Thompson regrets that he cannot answer individual letters.