There can be rats in villages. There can be little rats and big rats the little rats flee away when the player gets up close to it. And the big rats will attack the player when up close to it. When rat killed it will give you rat meet and rat skin. And if a cat comes close the cat will attack the rat and if a cat attack a big rat the big rat will flee like the little rats. But one thing rats will not spawn any were except in villages.