I took a break from writing to have lunch, and over that time I watched an episode of Babylon 5 about an outbreak of an alien plague on the space station.
At one point, the doctor compares the plague, "Drafa," to the Black Death. He says that "three-fourths" of Europe was wiped out in the Black Death, and that since many people thought the Black Death was the work of the devil, they killed cats "by the millions" -- considering cats agents of the devil. Naturally, this only sped the spread of the disease, since the cats were the only creatures keeping rats (and their fleas) in check.
Aside from demonstrating that doctors of the future aren't very good at fractions (three-fourths is a far cry from the generally accepted death toll of one-third), this was the first time I had heard this story about people killing cats in response to the Black Death. It sounded to me like an urban legend, or something half-remembered by a writer who thinks 3/4 of Europe died in the Plague.
I did a little bit of cursory checking, and while I found many references to the slaughter of cats just before the Plague or during the Plague, I didn't find any in reliable sources. I did, however, find reliable modern sources stating that the Bubonic Plague (the most likely contender for the Black Death) is fatal in cats.
So, I ask those specialists out there, is there any truth to this little morality tale about killing cats? Are there accounts of cats being killed in record numbers? Are there accounts of cats dying in record numbers from the Plague itself? Or, perhaps, did some people ascertain that since cats too were dying of the Plague, they might have been carrying it? Does anyone know the truth of it?