cats are super adaptable, you can amputate on leg without any problem for recovery. i had to make a choice a couple of years ago between cutting my kitties front leg or letting her die of cancer, and now she is super lively and jumpy. i had to give up my pocket money for the year before to convince my parents to let her live (the ghouls) but that was possibly the best use i made of my money in my life yet.
I mean my parents put our dog down cuz one of her legs was giving out and her other back one was giving out too. She was really old and had a couple other issues and it was getting to the point where she probably would have had some other life threatening health issue by next week. Probably had cancer as well, we felt a bunch of different bumps on here, but like if she was a year or two younger we probably would have just amputated it or come up with some other solution