Sometimes a high-pitched screech can work .. sometimes it just makes them more excited about the 'game' they're playing (gnawing on you). Have you tried redirecting it to a toy? Play with them with a toy instead and shove it in their mouth every time they try to open it to get you instead. If it persists, I would say something of your choice of 'no biting' 'ouch' and get up and walk away. Repeat as necessary. Eventually they learn that means game over. Be sure there are lots of things that the pup CAN chew on ... nylabones, raw bones, other appropriate toys. Maybe you need to do something to let it expend more energy. Sometimes they get wound up because a) they need to exercise or b) they're tired and need a nap. If the pup gets too wound up (think Tasmanian devil), put it in its crate for a nap.
Xan Varik von Fernheim (born 4/3/13)