I fostered a kitten through post-amputation once. It was probably hardest on the humans in that we were so worried about him. He was much, much better after a few days and was running around like a maniac, playing like a normal kitten within a week. I also have a three legged dog who has been that way for ten years now (I adopted him that way) and he does just fine. Hope your kitty has a speedy recovery and adjustment.