I used to think that if they made it through the first four days they would be fine. As far as starve-out, I think that still holds for the most part. But kits can die of injuries from being stepped on or by being dragged out on the wire later than that. Once their eyes are open and they are well-furred, it is unusual to lose a kit, unless there is a congenital problem that cannot be seen. The next big worry is weaning enteritis. It's not something I've had to deal with yet, but it can be a heart-breaker, I'm sure. Feeding lots of good grass hay is the best preventative I know for this problem.
