Ringworm in Dogs, Cats and Humans: The Gift That Keeps on Giving

Cat Ringworm

Oops… I did it again. I played with my patients and now I have ringworm: One flaky pink spot just under my left cheekbone, another itchy smudge on my right wrist, and the last, a blooming patch of shiny skin perched atop my décolletage. So pretty.

But I take heart in knowing I’m not alone. One of my technicians has ringworm lesions on her upper lip, forehead, and the nape of her neck. This travesty, along with a constellation of blemishes cascading down her arms, confirms that we must’ve been frolicking with the same patients (most likely those adorable scraggly kittens we couldn’t keep our hands off).  

As if this ringworm-sharing adventure wasn’t already bad enough, just yesterday I happened upon the worst of it: My 11-month-old Malinois, Violet, is sporting a suspect spot between the toes of her left front foot. This, along with a can’t-be-anything-but-ringworm splotch on her upper lip (yes, the very lip she likes to nuzzle us with), confirms my suspicions. Sigh.

Is It a Worm?

By now you’re either feeling very sorry for me (and well you should) or you’re just plain confused. Isn’t ringworm a worm? Why would it attack your face?

OK, so for those of you understandably perplexed by the veterinary misnomer that is “ringworm,” let me explain.

In spite of its unappetizing and highly misleading nomenclature, ringworm is not caused by worms. Rather, a fungus is to blame. The term ringworm results from the characteristically ringlike lesions observed on the skin of its hapless victims. And it’s most often brought to you by a fungus known as Microsporum canis. (Although two other species of fungus can also cause ringworm infections, they do so less often.)

Scientifically speaking, all of these ringworm-y fungi are referred to as dermatophytes. Which is why the disease state they trigger is referred to as dermatophytosis. And, as you might’ve guessed by now, the dermatophytes that cause ringworm are not only contagious between animals, they’re zoonotic too (which means they’re transmissible between humans and animals).

The Unflattering Effects

Here’s how they work: The dermatophytes that cause ringworm are microscopic organisms that invade the superficial layers of the skin, hair or claws. Because fungi thrive in moist environments, they’re especially persistent in humid climates and damp surroundings (like Miami, where I live). Which means that my Violet could’ve just as easily caught it from me as from the moist soil she loves to root around in.


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