Someone pointed out that we are probably dealing with a pack of coyotes, which explains why our dog can't handle the situation. He is chasing some of them while one grabs a lamb. Regardless of how many are out there, we are spending the night in the pasture now. My shift is 8 to midnight. My oldest daughter does midnight to 5 a.m., and my youngest daughter is there from 5 to 8 a.m. I think our presence is probably enough to deter them, since coyotes are shy animals and don't like humans. We do hear them sometimes, but they aren't getting very close.
It's time for my shift now. Gotta run!