"He really loves those treats!" Mrs. Singh said.
Timmy doesn't just love these treats, I thought to myself, regarding his beer keg shaped torso. But he was a happy dog and a good patient and we weren't going to discuss his weight again today. Today we were going to discuss his ears again.
"So, his ears are bugging him again?" I asked as I crouched down to scratch Timmy's neck and then carefully lift up his right ear flap. The tail metronome slowed down a little.
"Yes, he started shaking his head again yesterday and I don't have any drops for him anymore."
Timmy's right ear was bright red and the ear canal was filled with a sharp smelling black substance. I gently inserted the tip of my otoscope to look a little deeper down the canal. The whack, whack, whack of Timmy's tail stopped entirely. He wasn't smiling anymore either, but he stayed still and let me perform the examination. When I was done I straightened up, gave Timmy another treat and told Mrs Singh, "I'm afraid it's a yeast infection again."
Often I will swab the ear and look under the microscope to make sure that I know what is growing in there, but in this case it was so characteristic and it had happened so many times before that it wasn't necessary. Mrs. Singh was horrified the first time Timmy developed a yeast infection because she associated it with yeast infections in people, but it is a very different situation in dog's ears.
Yeast are normally resident on their skin and in their ears in low numbers. We all have a beneficial ecosystem of bacteria and yeast living on us in balance with our system. The yeast are however similar to baker's yeast in that they will multiply rapidly in warm or moist conditions. If a dog's ear canal becomes inflamed it is like turning the oven on when you're getting ready to bake bread. This is especially true for dogs with big ear flaps (closing the oven door!). Dogs with more erect ears do occasionally also get these sorts of infections, but they are much less common. As the yeast multiply they create that strong smelly waxy discharge and they further inflame the ear, creating a vicious circle of ever worsening inflammation and yeast infection.
Ok, you say, that makes sense, but why are the ears inflamed in the first place? In a word - allergies. While there are some other triggers, allergies account for the great majority of these. This sometimes surprises people because they we were unaware that dogs could get allergies and they are surprised that the allergies would only affect the ears. Regarding first surprise, indeed dogs do get allergies. Do they ever! Allergies are in fact extremely common, especially in some breeds. There is a whole separate lengthy conversation that can be had about allergies, but for the purposes of the ear discussion, suffice it to say that they are usually environmental allergies to house dust, pollen or mould, and occasionally food related allergies to the primary source of protein in the diet. Allergies can come on at any age and can change over a pet's life. And with respect to only affecting the ears, in part this is because the ears have the most sensitive skin in the body, and in part it is because the closed-oven-door feedback loop makes allergies there far more obvious.
Incidentally, you'll recall that I mentioned that moist conditions can also encourage yeast to grow, so occasionally we will see these infections after a dog has been swimming or been bathed.
I had explained all this to Mrs. Singh before, but she found she just couldn't stick to a diet for Timmy to try to address a possible food allergy, and she wasn't that interested in going down the more complex path of pursuing environmental allergies. The drops worked well and she prefered to just refill them as needed. I explained again the need to clean the ears regularly as the normal self-cleaning mechanism had been damaged by the repeated infections. And I explained again the need to finish the entire course of drops rather than stopping as soon as the symptoms subsided, but I could see that she was beginning to tune me out. I was refilling the drops and that's what she came for. And you know what? To be honest, do I follow each and every piece of advice my doctor or dentist gives me? Just ask me about flossing... Everyone just does their best. All we doctors can do is try to nudge the definition of "their best" a little further along.
Now that the poke, poke, poke and the blah, blah, blah had stopped, the whack, whack, whack began in earnest again. Timmy knew we were done and he was wagging and smiling and so clearly hoping for a good-bye liver treat that I had to smile right along with him.