Don't know about a cat but my dog lays at the doorway to my flower room whether it's closed or open.
How could you tell if an animal is high or not?
You can tell when their sort of spaced out, laying down, eating more/faster than usual. While neither is in itself a sign, combinations can lead one to believe an animal is high.
My dog for example, enjoys a small amount, he'll put his front paws on my knees while I smoke, and wait for me to blow a few hit in his direction, once he's had enough, he'll go lay down, or chew on something he normally wouldn't chew on, like the milk crate in my basement lol, all the while not really sure exactly of what it is he's doing, just that he want's to do it.