Otitis Externa (External Ear Infection)

by Bruce W. Little, DVM

Otitis externa is an inflammation of the external ear canal that begins at the outside opening of the ear, and if not controlled can extend inward to the ear drum and eventually to the inner ear. There are a multitude of agents that can cause otitis in dogs and cats including bacteria, fungi, yeast infections, foreign bodies such as a stem or seed from a flower or plant, ear mites and other parasitic insects and allergic dermatitis disease. There are other possibilities that can contribute to or cause otitis in both dogs and cats. The breed and body shape of the pet can influence its predisposition to otitis. Floppy eared dogs that have an ear that flaps down over the opening to the ear canal can create an environment that is ideal for the growth of bacteria, fungi and yeasts because in most cases these organisms require a warm, moist environment in which to replicate and flourish. Dogs whose breed predisposes them to going in water such as the retriever breeds that swim in pools, lakes, or the ocean set up the warm, moist environment in which agents that cause or contribute to otitis can develop. You can minimize the amount of water that gets into the ear canal by using a head cover purchased from Aquabandit at http://aquabandit.com/ if your dog is prone to taking a swim. Some breeds of dogs will naturally grow hair in the ear canal opening that may need to be removed in order for air to enter the ear canal and dry the lining of the canal which impedes the growth and development of these organisms. The ear canal is lined with skin, much like the skin on the face and the rest of the pet’s body. If the pet has allergic dermatitis or food allergy dermatitis, then the ear will itch and burn just the same as the other skin on the body causing inflammation and irritation to the area.

The anatomy of the ear of dogs is shaped differently than human ears. In humans, the ear canal is straight inward from the ear opening to the ear drum or the middle ear. The ear canal lays parallel to the ground in the upright standing position in human anatomy. However, in the dog, the first half or so of the ear canal from the opening inward is directed downward toward the feet of the animal and then makes a 45 degrees turn to the parallel position before the canal reaches the ear drum. This anatomical fact can trap water, or at least moisture, in the ear canal which sets up the perfect environment for bacterial, fungus and yeast growth, causing the infection to progress and perpetuate. Sometimes surgery must be performed to open the ear canal that allows it to dry out and slow the growth and expansion of the infection.

There can be further complications if otitis externa is not controlled. The second stage is in the middle ear that includes the ear drum. If the inflammation is severe enough and the pain high enough that the dog or cat scratches, paws and rubs its face on furniture and carpeting to a high enough level, the ear drum may be ruptured in some cases. A ruptured ear drum will lessen the hearing ability of the pet, at least in the ear in which the ear drum was ruptured. In the third and final stage of ear infection, otitis spreads to the inner ear which houses the pet’s balance system. At this point, some pets especially dogs, are reluctant to open their mouths or chew their food or chew toys. Many may develop a head tilt, droopy lips or eye lids and problems with their balance and standing upright. It is very important for you to take your pet to the veterinarian before further damage is done in the middle and inner ear. Once those areas become involved, the condition is much more difficult to treat and the pain and discomfort to the pet is elevated. Also, the cost to cure and control the conditions of advanced otitis is significantly increased as the disease migrates to these vital parts of the pet’s ear especially if surgery is required.

The first signs of otitis externa may be excessive scratching of the face and ears or shaking the head. Pets may develop an ear discharge that may or may not have a foul odor. Sometimes we will smell the odor, but not see any discharge. When you observe these signs in your dog, it is best to see a veterinarian as soon as possible. The quicker the itchy skin and pain are controlled, the better the final results. It can take considerable time and a variety of diagnostic tests for your veterinarian to determine the underlying cause of the otitis. The ear usually has to be cleaned thoroughly and any debris or discharge removed. If the underlying cause of the condition appears to be allergic in nature, allergy testing and food trials must be conducted in order to eliminate the allergen that is causing the problem. Sometimes bacterial cultures must be obtained in order to choose the proper antibiotics or fungicides to use. Since many different types of bacteria may be the cause, it is important to choose the most effective antibiotic, fungicide and pain relieving products to use.

Your veterinarian will instruct you how to perform follow-up treatment on your pet at home. These instructions must be carried out precisely as prescribed in order to maximize their effectiveness. If you are incapable of carrying our these instructions, call your veterinarian and request guidance, as it is very important to maintain proper methods in order to treat ear conditions. You may be asked to clean the dog or cat’s ears on a regular schedule. I recommend a low-stress method that keeps the dog or cat as comfortable and quiet as possible. Gather all your supplies before beginning the process. Place a blanket on a table or other elevated piece of furniture for a warm, comfortable feeling. Some veterinarians will have you spray a hormone, called pheromone, which can be obtained at most pet shops and will help to keep the pet quiet and complying. Offer your pet treats as you begin the process and continue to offer a treat throughout the cleaning. Use the least amount of restraint as you can to keep the pet calm during the process.

I have just returned from a national veterinary conference where Bayer Animal Health launched a new product to treat dogs who have otitis externa with a single dose administered by your veterinarian. The Bayer promotional flyer states, “Claro™ provides a potent combination of ingredients in the only veterinarian-administered, single-dose treatment regimen that’s proven effective against susceptible strains of yeast and bacteria associated with canine otitis externa.” The product, Claro™, contains a high-potency anti-inflammatory corticosteroid that helps to relieve the itching and burning of ear canal inflammation. It will be interesting to see how this new product works. For more information about this product, go to www.OneDoseZeroHomework.com or ask your veterinarian about Claro™. At this time there is no indication that Claro™ can be used on cats.

Follow your veterinarian’s instructions for cleaning your dog’s ears and administering medications. Be sure to bring your dog in for each recheck appointment your veterinarian schedules. It may be necessary to schedule periodic rechecks even after the inflammation has subsided. Otitis often reoccurs in dogs, and the medications you used that cleared it up the first time may not work a second time because a different type of infection or allergic response may have developed. Therefore, it is important to see your veterinarian if any signs of otitis recur. Many times otitis externa is not about curing the condition, but simply managing the problem. By following your veterinarian’s recommendations, you have the best chance for an outcome both your family and your family member pet can live with.