[ health]
Otitis
[Ear Infections!]
in Dogs & Cats
By Lillian M. Roberts, DVM Country Club Animal Clinic
E
ar inflammation and infections are a common and often frustrating condition in pets. Because of the conformation (i.e., design) of the typical quadruped ear canal, infections are not always apparent until they are quite advanced. Otitis is the medical term used to describe ear infections—although to get technical, the term actually refers to inflammation. The difference between infection and inflammation is the crux of how the condition develops. But, for practical reasons, the two terms are used interchangeably. The type we see most often is called otitis externa—infection of the ear canal. Almost all cases of otitis have an underlying cause—the thing that triggers inflammation. In most cases, this is an allergy to something in the animal’s environment or its food. Just as allergens cause our eyes to water and our sinuses to swell and itch, they cause dogs’ (and cats’) ears to itch. And just as humans can develop sinus infections as a result of chronic inflammation, so can dogs’ ears become infected if the underlying allergy lasts a long time and isn’t treated. Wow, that sounds easy, right? Just treat the allergies and no more infection! If only it were that simple. Allergy treatment is a multi-billion-dollar industry in humans for good reason. The good news is, humans suffering from chronic allergies have led
6 petcompanionmag.com
to a lot of money being spent on developing treatments—and many of those dollars spill over or go through initial testing in dogs. The bad news is, while we have learned a lot about the causes—and treatments—of otitis in pets, they can still be very difficult to eliminate. Let’s take a look at how otitis develops. First, we have inflammation due to allergy, chronic wet/dry cycles in the ears from swimming, the presence of an irritant such as a foxtail, or even overzealous cleaning (or some combination of these). Anatomy works against the pet here—otitis is more common in dogs with ear flaps that hang down, reducing air circulation that helps dry and aerate the canal. Excess hair that protects the healthy ear against invading pathogens and foreign objects works against us when the ear becomes inflamed and increased secretions gum up the works. The lining of the ear is modified skin closely connected to cartilage. Cartilage doesn’t “swell” because it’s considered “hard tissue”—basically holding its shape while the lining thickens and changes. These changes alter the normal defenses— basically the “immune system” of the ear is suppressed. The surface becomes reddened and cells that secrete protective compounds, such as ceramides and wax, are either stimulated or suppressed, resulting in an ear that can’t defend itself. The lining of the ear, like the skin, is basically covered with bacteria and a few yeast. These don’t cause problems most of the time—they simply live in harmony with their environment. But add a little heat, constant moisture, and a dark environment with minimal air flow, and you’ve basically created an incubator. Microbes
take advantage, multiplying and thriving. This triggers an even more exaggerated inflammatory response, which further benefits the microbes, and it’s “Off to the races!” Normal ears secrete a small amount of wax, but irritated ears can really work overtime, producing increased amounts of wax, serum, and even blood or pus, depending on other factors. This material accumulates in the ear canal—a tube that is about seven times longer than our own ear canal and shaped roughly like an “L.” Gravity works against the pet, and the hair that naturally lines the canal becomes wet and gooey, clogging up the tube. This causes pain, of course, and often a bad odor. But even the odor is held back by the floppy, hair-covered ears. These are all reasons why ear infections can get so bad before the pet’s owner is even aware there is a problem. Once you’ve been through one, you tend to be more aware of the signs—head shaking, holding the head to one side, and sometimes just holding it down in a “hangdog” posture. Some people first notice the stink; others recognize a problem when the pet cries out when its ears are massaged. OK, so you think your dog has an ear infection. Now what? First: DON’T TRY TO DEAL WITH IT YOURSELF! Don’t stick Q-tips in the ear, and don’t use the “ear mite treatment” recommended by the well-meaning clerk at the pet store. Not only will these NOT fix the problem, they will only postpone effective treatment, often turning a mild problem into a much worse one. Please, make an appointment to see your veterinarian. What we do will depend on many things. In most cases, we will take a sample from
