Most everyone is aware a dog’s hearing is far more sensitive and accurate than human hearing. But did you know about the other differences? Why do dogs get so many ear infections? Are specific tests needed before treating an ear infection? What is the treatment and are there any risks to treatment? What if an ear infection goes untreated? Can ear infections be prevented or minimized in number? All good questions for which there are answers.
Otitis externa is the veterinary term for an ear infection. Unresolved otitis is the most common reason pet owners seek a new veterinarian and the number one reason they leave their current veterinary hospital. Understanding a dog’s ear canal anatomy and the biology of otitis will help in answering the questions above.
Canine ear canal anatomy is very different than that of a human, (see illustration) A human ear canal is a straight, horizontal path to the ear drum. Canine ear canals have an outer, vertical canal followed by a horizontal canal and finally the ear drum. It is a dark, narrow pathway with little airflow. Many breeds of dog have large ear flaps impeding airflow even more. It’s a great hiding place for bacteria and yeast from the dog or the environment to set up housekeeping. Remember, a dog’s normal body temperature is nearly the same as a laboratory incubator. All it takes is a little bit of moisture from swimming, bathing or even rain, to encourage the infectious process.
It is necessary sometimes to perform lab testing to get a general idea of what type of bacteria or how much yeast are living in the ear canal. Veterinarians frequently swab the ear canal to check for infectious bacteria and yeast under a microscope. This can be very helpful in determining which ear medication will be most successful in resolving the infection. Much less frequently, an ear infection will persist with first line treatment and it may be necessary to culture the organisms growing in the ear. Not surprisingly, there are resistant bacteria in veterinary medicine just like human medicine. A culture not only identifies the exact bacteria but also demonstrates which antibiotic is most effective against that bacteria.
It is critical that owners follow the treatment plan set forth by the doctor. Failing to do so usually means the ear stays infected or the client has created a resistant bacteria with intermittent dosing. There are risks to treating ear infections. ALL ear antibiotics have the potential to cause deafness, especially in older dogs where the ear drum has become weaker with age. It is not a common side effect so we still start treatment. Untreated ear infections lead to scarred and narrow ear canals which increases the likelihood of future infections and makes them more difficult to treat. Ear infections frequently cause dogs to violently shake their head. The trauma to the ear pinna from head shaking can cause a pocket of blood (hematoma) to form in the ear flap. This condition often requires surgery.
After the designated treatment period is successfully completed, it is important to DO YOUR RECHECK with the veterinarian. The doctor will look deep into the ear canal with an otoscope, far beyond what the owner can see from the outside, to be sure the infection is resolved. If there is residual infection in that lower horizontal part of the canal, the part the owner can’t see, the infection usually returns within two weeks.
There are measures dog owners can take to minimize the number of ear infections their dog gets. Prevent water from getting into the ear canal during bath time by putting a cotton ball at the opening of each ear canal to absorb any water that might run into the canal. Always remove the cotton ball immediately after the bath. Using an approved canine ear cleaner that contains a drying agent helps with excess moisture in the canal. Never use hydrogen peroxide or straight alcohol in any ear canal.
Ear infections in dogs always require treatment by a veterinarian to ensure comfortable and healthy ears and avoid complication.