Your dog giving birth is a joyous occasion, but the event does tend to be a messy one. Keeping Sasha's nesting box clean is vital to her health and the health of the puppies, and keeping Sasha clean is one step in accomplishing that. You should change out the bedding once your dog is done giving birth. She'll clean her puppies. You'll want to give her a bath, but you shouldn't do it right away.