some dogs can have sensitive stomachs and react to certain kinds of meat. If the lamb is not working for the one dog try switching to one of the other meat medellions that NV has ( they make beef ,chicken ,venison, lamb and I think rabbit,although the stores in my area don't carry the rabbit)Dont give up on the raw just yet. Both my dogs do great on the raw and eat all the varieties without any problems , but Tia my tzu cross has a sensitive stomach to certain brands of kibble and will throw up, so I know what you are going through ! Hang in there!
Eileen