Inspiration doesn’t bubble up when you’re sick as a dog. Granted, my current bug is respiratory, not gastrointestinal as the phrase might suggest, but even so—why dogs? Do they get sicker than the rest of us, or more often?
“Sick as a dog” is said to go back at least to 1705, though I haven’t found the reference yet. Oxford English Dictionary, anyone? According to the OED, early phrases and proverbs smeared dogs as vicious, miserable working beasts that spread disease.
Who doesn’t love a good origin story? We thirst to know how a word, phrase, belief, cultural practice, or epidemic began. When evidence runs out, make something up. It stretches the imagination and generates hypotheses to explore. Just remember to distinguish evidence from speculation or hypothesis, to avoid getting mired in conspiracy theories not fit for a dog.
I'm a historian who writes novels and literary nonfiction. My home base is Madison, Wisconsin.