If your cat can't move his/her back legs, I hope you've had him checked by a vet since you asked the question? Several things could cause the loss of use of his/her legs and only a vet can diagnose and treat (if possible), once they know what is wrong. Pinched nerve, injury from being hit by car, injury from a fall, saddle thrombosis, poisoning .. The list goes on.
It's been over 14 hours since you asked your question. How's the kitty now?
All the best ....
It's been over 14 hours since you asked your question. How's the kitty now?
All the best ....