Short story: “Cat in Glass”
by look i have opinions
“Cat in Glass,” by Nancy Etchemendy
First appeared in The Magazine of Fantasy & Science Fiction, July 1989; collected in Cat in Glass and Other Tales of the Unnatural; anthologized in American Gothic Tales and also in Tails of Wonder and Imagination (which I found here)
Awesome creepy fun, if horrifyingly mauled kids are your idea of fun.
I’ve had the last few lines etched in my memory for over ten years now. Right down to the characters’ tones of voice.