Ear mites can torment cats, on Martha’s Vineyard and worldwide


Cauliflower, a middle-aged cat, first came to see me two years ago. She had recently moved to the Vineyard and was due for her annual exam. Her owner mentioned a previous history of ear mites. I could see right away one of her ears was all scarred and crinkled.

In people, this is called cauliflower ear and is often seen in boxers (human boxers, that is, not canine), wrestlers, and other such folk whose activities involve repeated head trauma. In dogs and cats, the trauma leading to cauliflower ear is typically self-induced. “She shakes her head when we touch her ears,” Cauli’s dad reported.

Animals may scratch or shake their heads for many reasons. Fleas. Ear mites. Yeast or bacterial infections. Allergies. Regardless of the underlying cause, sometimes all that scratching and shaking causes a blood vessel to pop under the skin. The ear then puffs up like a little water balloon or, more accurately, a blood balloon. Technically called an aural hematoma, it’s really just a giant blood blister. Aural hematomas can be addressed medically, or surgically, to obtain more cosmetically pleasing results. But if left untreated, most eventually shrivel to this odd, gnarled appearance.

Inside Cauli’s right ear canal was thick, dry, grey debris. I swabbed out a glob and mixed it with mineral oil on a slide. Some veterinarians say they can see ear mites with the naked eye, but I can barely find the cat with my naked eye, so I headed over to the microscope. Otodectes cynotis is the scientific name for these critters. When I find them under the scope, I always call owners over for a peek. The squirming bugs make quite an impression. But not this time.

“No mites or mite eggs,” I pronounced. Flipping back through Cauli’s off-Island records, I noted that although she had been treated several times for mites, there was no record of their presence being definitively documented. The shelter she had come from had checked a box that said “ear mites,” but I suspect they made this assumption based on the gross appearance of the ear debris and the fact that she was itchy. That’s an understandable assumption.

The majority of ear problems in cats are due to mite infections. (Not so with dogs, but that’s another column.) Should I assume Cauli had ear mites now, despite lack of concrete proof?

I once read a rather sad study in which researchers took unclaimed shelter dogs and cats that were slated for euthanasia and checked them for ear mites as I had done with Cauli, i.e., microscopic examination of ear debris.

Now if you are squeamish or particularly soft-hearted, skip the rest of this paragraph. The animals were euthanized and their ear canals sectioned, then thoroughly evaluated microscopically, slide by slide. This detailed postmortem examination revealed that a small but significant percentage of animals that had not shown mites on the “debris test” did in fact have Otodectes infections. I remembered the old adage “absence of evidence is not evidence of absence” and decided to hedge my bets,

“Let’s treat with Tresaderm,” I suggested. This concoction contains antibiotic for bacterial infection, anti-inflammatory to calm itching, and a third medication useful against both yeast and mites. Two weeks later, Cauli’s ears seemed much improved, though still containing more debris than a normal kitty ear. “Cauli may have underlying issues like allergies,” I pronounced, and advised additional testing if the problem recurred.

Guess what? The problem recurred. Over the next year, Cauli’s owner treated periodically, but after a while she stopped responding as well to the Tresaderm. “We can run tests,” I suggested. “And maybe try a 10- to 12-week hypoallergenic diet trial to see if she has food allergies.” I glanced at Cauli’s owner, trying to interpret his quizzical expression. “Or we could just keep it simple and try different ear ointment,” I concluded.

The owner relaxed a little and nodded. After all, topical medication had worked in the past, at least to some degree. I sent them out the door with new medicine and instructions to call if the problem persisted.

Guess what? The problem persisted. The new medication stopped the itching, but it would soon start up again each time they discontinued treatment. By the time Cauli’s annual visit rolled around this fall, we agreed it was time to get to the bottom of things.

I rechecked for ear mites. Still no creepy crawlies. I heat-fixed ear debris to a slide, stained, and examined it on the microscope. Skin cells, wax, a smattering of yeast and bacteria. Those organisms might be causing Cauli’s problem, but there was a good chance these were just opportunistic bugs taking advantage of ears that were already inflamed for other reasons.

“Ear problems are far less common in cats than dogs,” I explained. “And when cats do have itchy ears, most of the time mites are the culprits…. But since we’ve pretty much ruled mites out, the next most likely cause is food allergy or inhalant allergy.”

The gold standard test for food allergies is 10 to 12 weeks on a special “elimination diet.” It must be done in a scientific way. You can’t just go to the grocery store, randomly pick a different brand of cat chow, and see if Cauliflower gets better over the weekend. A true elimination diet trial requires commitment. I like using prescription veterinary diets that I feel confident are truly hypoallergenic. After all, if you’re going to all this hassle and expense, you might as well do it right.

Cauliflower went home with a big bag of hypoallergenic food, and another topical medication for the yeast infection. She’s coming back soon for a recheck.

I hope this will prove to be the answer. If not, our next step may be testing for inhalant allergies or even starting her on oral corticosteroids and see if that helps. That one cauliflower ear may give her character, but we want to give her relief.