Dogs with ear problems represent a sizeable portion of veterinary practice: Nary a day passes without me needing to wade into a pair of stinky, discharge-filled ear canals. These dogs, many of which have suffered one ear infection after another, have often had problems for years. The owners have used dozens of medications, often in combinations of two or three products per day. Just as often, the owners are frustrated and working really, really hard to achieve marginal results. It isn’t pretty. It isn’t fun. The worst part: it isn’t effective.
It’s helpful to consider the nature of these ear problems: There is nothing wrong with the animal’s ability to hear. All of the sound-processing equipment is fine. Ear problems are actually problems of the specialized skin lining the ear canal. What does this tube of skin do? The tubular SHAPE of the ear canal captures and conducts sound impulses to the eardrum. The SURFACE of the ear canal has a completely different job. This specialized skin must keep the ear canal clean so that sound is not prevented from reaching the hearing apparatus.
That’s right! A normal ear canal cleans itself, quickly ejecting debris generated by the constant shedding of cells that takes place at the surface of all skin everywhere, but would build up in the depths of the canal. The ear canal secretes specialized oils that suppress the growth of yeast and bacteria, microorganisms that might otherwise overgrow in the moist depths of the canal. Dogs are often avid swimmers, but the moisture and muddy material that enters their ears is swiftly and efficiently removed by an endless river of wax and skin debris that flows up and is expelled from a normal ear canal. So, when your dog has dirty, stinky ears, it’s a sign that the ear canal is not working as it normally should.
The most common cause of ear canal dysfunction is inflammation. In a dysfunctional ear canal, skin debris isn’t removed, but instead accumulates; normal, anti-microbial earwaxes change and lose their ability to suppress the growth of microorganisms. The inflamed skin of the ear canal secretes more and more waxy material, which loses the normal, smooth, odorless, off-white character of healthy earwax and becomes a thick, golden to red-brown, odorous, grainy goop. Normal skin yeast, whose numbers are suppressed by the wax, overgrow in this nutritious ear-soup, resulting in a yeast infection. Later, bacteria colonize the mix, overgrowing the yeast and turning a yeast infection into a bacterial infection and necessitating a trip to the veterinarian’s office. Over time, this bacterial population is selected for drug resistance by repeated antibiotic treatment. In the end, the chronically inflamed and infected ear canal becomes narrow and scarred so that it looses the ability to function properly, and the bacterial infection evolves to a point where no antibiotic is effective. Poor doggie!
There is a tendency among veterinarians to focus on the infection, and indeed, infection control is critical to restoring these ears to health. HOWEVER, my point is that most ear problems are initiated by inflammation, with infection by yeast and bacteria developing as a RESULT of the ear canal dysfunction that inflammation causes. But what causes the inflammation?
The simple and most common answer is: ALLERGY. In dogs, skin cells that create and release histamine (the chemical that causes redness, itching, and tissue swelling) are concentrated in the pinna (look it up), ear canals, feet (especially the front feet), the top surface of the front legs, and along the trunk (a “broad brush” description - individual dogs will vary). This is the dog’s stereotypic cutaneous eruption pattern for a systemic allergy. In order for this pattern to occur, an allergen must be absorbed into the bloodstream and delivered to the cells that release histamine. The dog’s skin erupts where the cells are located, regardless of the allergen causing the reaction. To do this, the dog must eat or inhale the allergen.
Between one-half and three-quarters of all chronic ear infections are promoted by food allergies; a smaller fraction result from allergy to inhalants such as pollen and molds. Very, very few are caused by things like water in the ears. Healthy, normally functioning ear canals simply won’t allow an infection to become established. It’s really that simple.
If your dog suffers from chronic or repetitive ear problems and you haven’t performed a thorough and reliable 30-day hypoallergenic diet trial, you’re missing your big chance to restore your dog’s ears to health. Ask your veterinarian about ears and allergy. You’ll be glad you did.