Overcoming the three biggest obstacles when treating otitis externa

Round and round it goes. Will it ever stop? (Kathy images/stock.adobe.com)You know the drill: You start off great-it's an easy case of traditional otitis externa. And then… you and the pet owner circle around the ear cleaning drill a little. And then… you find out the patient's shaken most of the medication out of its ears. And then… you're in the endless tunnel of scheduling a recheck appointment.

Since canine otitis externa is a such common presentation in general veterinary practice, you can't just throw your hands in the air and call it a day. Most experts agree that treatment failure usually results from insufficient ear cleaning, improper or inadequate treatment and poor client compliance-a veritable obstacle course of potential pitfalls. Let's break it down.

Obstacle No. 1: Insufficient ear cleaning

Healthy ears are self-cleaning, but diseased ears are not. That's why thorough ear cleaning is one of the keys to successful treatment, says James Noxon, DVM, DACVIM, from Iowa State University's College of Veterinary Medicine. “Without a thorough cleaning, any topical medication is less likely to be effective,” he says. Thoroughly cleaning the ear helps to remove purulent discharge, debris and biofilm that may block movement of the medication into the horizontal canal.

In patients with proliferative, end-stage otitis externa, it can be very difficult to get cleansers deep into the ear canal, says Craig Griffin, DVM, DACVD, from Animal Dermatology Clinic in San Diego, California. To achieve this when a dog is anesthetized, he advises, use a 3-mm otoscope cone to dilate the ear and place the cone as far into the canal as possible. “You can pass an ear loop down the canal just past the tip of the cone and then fill the cone with cleanser and slowly pull the cone out,” he says. This allows a layer of cleanser to be deposited on many canal folds as they fall back in place as the cone is removed.

Owners of pets that require multiple in-clinic ear flushes may be reluctant to allow repeated general anesthetic episodes, Dr. Griffin says. Instead, sedatives and analgesics are sometimes used. “In these cases, even though a patient's laryngeal reflex may be present, it can be suppressed, so take precautions to prevent inhalation pneumonia and avoid spreading resistant Pseudomonas species and methicillin-resistant Staphylococcus species to the lungs,” he advises.

Dr. Griffin also notes that any time you flush an ear with a ruptured tympanic membrane in a sedated dog and an endotracheal tube is not in place, the dog's head should be angled down because the flush can go through the auditory tube to the back of the throat and be aspirated. “At my practice, we raise the racks on the wet table at one end and the dog is positioned in lateral recumbency with its nose at the low end of the rack,” he says.

Obstacle No. 2: Improper or inadequate treatment

If the wrong medication is selected, the right medication is not given for long enough or the underlying primary disease goes undiagnosed, the result will be recurrent infection. Acute ear infections should be addressed aggressively at the first visit, says Dr. Noxon. The infection should not be allowed to become more chronic in nature.

Recheck exams and cytologies are needed to ensure total resolution of the infection. Ear cytology must be performed on initial examination and with each recheck, Dr. Noxon adds. Partially treated infections can become chronic or, worse, resistant to treatment. Some ear infections may require more than 14 days of treatment despite many medications being labeled for 7- or 14-day regimens, he says.

Dr. Griffin advises extending the ears when cleaning or treating to elongate and straighten the horizontal and vertical canals; there is a small U-shaped “trap” between the canals that may harbor debris. Also vital to success is using sufficient volumes of cleaner and medication. In medium-sized dogs, the ear can hold about 4 to 6 ml; therefore, 1 ml of medication is insufficient.

Shortsightedness by the veterinarian can lead to insufficient treatment. “Veterinarians must prevent relapse or recurrence while searching for the underlying cause,” Dr. Noxon says, as chronic infections are often initiated by parasites, foreign bodies, hypersensitivities, keratinization disorders, or irritant reactions. These inciting causes can then allow disease states to build with problems such as atopy, Staphyloccoccus or Malassezia infection, or dry skin, worsening any original problem. Because of these multifaceted disease states, it is important to treat all components involved while educating the client appropriately.

Continue antiseptic, antibiotic or antifungal topical therapy until cytologic examination shows no inflammatory cells or DNA strands. It is common for practitioners or clients to discontinue therapy too early, especially if the ear looks reasonably good and there is no obvious odor or discharge. “I see many cases when I think it is time to discontinue treatment, but because of the results of cytologic examination, I continue,” Dr. Griffin says. “Be sure to caution owners to expect that, based on cytology, treatment may need to continue despite the ear looking better, and if all is clear they will be pleased and think you-or they-did a better job than expected.”

Obstacle No. 3: The client compliance conundrum

Another fundamental aspect of successful otitis externa treatment is pet owner compliance. And key to the buy-in? “Extensive communication that includes drawings and models helps clients fully understand the severity of the disease and the importance of their role in treating it,” Dr. Noxon says.

Be sure the client understands that simply treating the clinical signs will not help the pet; addressing the underlying cause is what's crucial. Dr. Noxon recommends explaining it this way: “There's a what, and there's a why. The what is what's happening right now. If you treat the what and fail to address the why, the what comes back. If you try to treat the why without treating the what, it appears you have treatment failure, because you still have all that stuff on top that covers things up.”