I've got a black cat called Moses and I think he may have PTSD. Several years ago he was bitten by a small brown snake( very poisoness), the snake had gotten into the house and Moses thought he'd play with it. Moses lived, after some serious vet bills that is. Soon after he was bitten he took on the whole PTSD thing, he very gingerly walks around and smells everything. Where the snake bit him in the house, he'll sit on a table and stare at the spot for ages. If he goes outside he'll go to walk through a doorway and before he gets to the door he'll jump three foot up in the air to jump over the doorstep just in case there's a snake near the doorstep and boy is he jumpy, he also has serious bad dreams, I presume. Then if there's anything on the floor long and skinny like a snake, such as a power cord, a belt, a piece of cord or the handle from a bag he freaks out.
The other day my daughters cat was visiting while she was away for the weekend, her cat Lucky is nearly as jumpy as Moses and blind in one eye, he was rescued by the RSPCA from a cruel home. Anyway both cats were play fighting and knocked my hubbys black leather belt off the back of a chair, the belt fell down, Moses jumped and ran, Lucky ran because Moses was running and poor Lucky ran smack into another chair because it was his blind side, meanwhile Lucky stopped behind the chair as he hit it, to turn back and see what it was that Moses had run from and the chair fell backwards on top of him. Luckily for Lucky the chair back is one with a gap in it and the chair settled around him on the floor, still made him jump but at least it didn't hurt him. The whole episode was hilarious, would of been perfect for Funniest Home Videos if I'd of had the camera out.
