Visiting Vet: Otitis

What to do about a case of the wobbles.

When is it otitis and when is it a tick-borne disease? - Wiki Commons

Limo, the German shepherd, cruised into my office last month with a complaint of lethargy and inappetence. OK, he didn’t exactly cruise. He kind of wobbled. Limo had barely eaten for days, and had a 104° fever. “Looks like tick-borne disease,” I opined. Veteran Vineyarders know the list: Lyme. Anaplasmosis. Rocky Mountain spotted fever. Tularemia. (And now Powassan virus, but let’s not go there!) We ran a few tests, settling on a presumptive diagnosis of Rocky Mountain spotted fever.

I wasn’t overly concerned that Limo was a touch unsteady on his feet. Rocky Mountain can occasionally cause neurological signs, but I thought he was just weak and woozy from the high fever and not eating. “He should start feeling better soon,” I said, handing his dad a vial of antibiotics. As we walked out of the exam room to the front desk, I remembered that I had also noticed a minor infection in Limo’s right ear. He had a history of recurrent bouts of otitis throughout his life. It wasn’t particularly bad today. Still, I wanted to be thorough. “Have any ear ointment at home?” I asked. His owner shook his head no. “Let me grab you something,” I said, then paused.

Now I’m an old dog, slow to learn new tricks. Seriously. I prefer sticking to products and protocols I’ve used for years and know well. So traditionally, I treat otitis with tried-and-true ointments that owners apply twice daily for seven to 10 days. Not every dog is cooperative. Not every owner is compliant. So just that week, I had finally decided to order one of the newer “one-and-done” ear medications. There are several on the market, each with pros and cons, but the main concept is a “single treatment” product your veterinarian administers right at the office. You and your dog go home with nothing more to do. Magic! I had some experience using a single-treatment product, but mine was old-fashioned — a thick, waxy, lanolin-based concoction that leaves the patient’s ear a gooey, sticky mess. I was ready to try something newer, something cleaner, that wouldn’t drip yellow goop all over owners’ expensive Oriental rugs … and I had just received my first box. “Let’s try this new treatment,” I suggested, thinking that Limo’s dad already had enough to do, giving antibiotics three times a day. He agreed and, rather than schlepping the 100-pound pup back into the exam room, I applied the medication right in the waiting room. Done! Easy! Except that evening, Limo’s owner reported that the big dog had developed “rapid eye movements.” He would continue the antibiotics and touch base in the morning if things weren’t better. By early morning, things were worse. I had them come right over, even before my office opened. Limo couldn’t stay upright, but would fall to one side, head tilted to the right, his eyes flicking rhythmically back and forth. I tried to look down his ear, but he wouldn’t hold still, and my assistant wasn’t in yet. On the other hand, his temperature had returned to normal, and when I offered him canned dog food, he licked the bowl clean.

I thought through the differential diagnoses. Rocky Mountain spotted fever (RMSF) can cause neurological signs, including head tilt and incoordination, and Limo had been wobbly on initial presentation … but his fever and anorexia were abating with antibiotic treatment. I wouldn’t expect RMSF neurological signs to worsen at this point. Maybe it wasn’t RMSF at all. Maybe he had some other primary neurological disease. A brain tumor. Encephalitis. This would require referral to a neurologist for definitive diagnosis. What about canine geriatric vestibular disease? Limo’s new neurological signs were consistent with this common, benign balance disorder, but wouldn’t account for the fever. Perhaps our initial RMSF diagnosis was correct and he had both RMSF and canine vestibular disease? Or perhaps our initial RMSF diagnosis was correct and the head tilt and incoordination were caused by the new medication I had so happily squirted down his ear?

Almost all medications commonly prescribed for canine ear infections bear the warning not to use unless the eardrum is intact. Ideally, we veterinarians examine every infected ear with an otoscope. Because of the anatomy of the canine ear, this involves inserting a relatively long, rigid speculum into the canal. The reality is that it’s often too painful for dogs to allow us to get that scope all the way down the canal. Even when we can, the eardrum is frequently obscured by debris. So over the years, I sometimes skipped the otoscope, I sometimes dispensed ear medications even when I couldn’t see the eardrum. Sometimes owners even just picked up medication without bringing the dog in at all. It’s never caused a problem. But this was a new product. I called the manufacturer. On their advice, I had Limo return and flushed his ear with copious amounts of saline. Then, with an assistant holding him firmly, I took a good look down his ear. There was a nice intact eardrum … no … wait … is that … drat. There, at the very top of the membrane, were two small perforations.

There is no way to know for sure what caused Limo’s symptoms. Here’s what I suspect. Limo had Rocky Mountain spotted fever, which caused fever, anorexia, and mild unsteadiness that began resolving once he started antibiotics. The new ear medication had a more fluid consistency than products Limo has had in the past, and thus may have leaked through those little holes in his eardrum into the middle ear, causing the additional balance issues. The manufacturer confirmed reports of other dogs having similar reactions to this product, and assured us that if the medication was indeed the culprit, Limo should make a full recovery. I’m happy to say Limo has been slowly but steadily improving. His owner has been wonderful, as always. And this old dog (meaning me) got an important reminder. Always try to visualize the eardrum, in every case, no matter how many times a patient has had otitis.