A house cat, accoring to the MM, can deal 3 damage with two claws and a bite. (Minimum damage is 1 HP for an attack.) And a peasant has 1d4 HP. So don't tick off kitty!
Yup. The day after I got this in email, I was cutting my parents' Maine coon's claws. He decided he didn't like it, so bit the fleshy part of my hand. Using Improved Grapple, he then executed, as a free action, a rend attack. He then released me and ran. This was a good thing, since I was now at zero hit points and staggered. If I'd tried to do anything strenuous, I'm sure I would have passed out.