Horses Can’t Vomit

Being the wonderful sister-in-law that she is, Pam helped me out with the origin of "sick as a dog." I miss Pammie and love her sense of humor! Yesterday she read my post and before going to bed last night I noticed that I had an email from her solving the mystery of where this saying came from.

"There are several expressions of the form sick as a ..., that date from the eighteenth and nineteenth centuries. Sick as a dog is actually the oldest of them, recorded from 1705; it is probably no more than an attempt to give force to a strongly worded statement of physical unhappiness. It was attached to a dog, I would guess, because dogs often seem to have been linked to things considered unpleasant or undesirable; down the years they have had an incredibly bad press, linguistically speaking (think of dog tired, dog in the manger, dog’s breakfast, go to the dogs, dog Latin — big dictionaries have long entries about all the ways that dog has been used in a negative sense).

At various times cats, rats and horses have been also dragged in to the expression, though an odd thing is that horses can’t vomit; one nineteenth-century writer did suggest that this version was used “when a person is exceedingly sick without vomiting”. The strangest member of the set was used by Jonathan Swift in 1731: “Poor Miss, she’s sick as a Cushion, she wants nothing but stuffing” (stop laughing at the back).

The modern sick as a parrot recorded from the 1970s — at one time much overused by British sportsmen as the opposite of over the moon — refers to a state of deep mental depression rather than physical illness; this perhaps comes from instances of parrots contracting psittacosis and passing it to their human owners."

-- www.worldwidewords.org