With all due respect, I do hope your father-in-law has learned a very valuable and painful lesson!

A cat bite is the second worse bite to a human's bite. Along with CrazyCatLady, I was also bit by a stray pregnant cat. Your FIL's mistake was waiting till it got real bad. I only waited 24 hours. I was very lucky.

Word of wisdom, ALWAYS watch a cat's body language. If the ears go back and there's growling or play biting, stop immediately. Otherwise it could turn out worse.

Hope your FIL has a speedy recovery.