Stage one of labor generally last 6 to 18 hours. Once the placental water sack "breaks" the first puppy normally arrives after 10 to 30 minutes of straining labor. After that, subsequent pups can take anywhere from ten minutes to four hours to be born.
After the dog starts having contractions the dog normally will have the first puppy within an hour or two. If labor has gone on for 12 hours or if she appears distressed take her to the vet immediately.
There are three stages of labor for a female dog. The first stage may take from 6-24 hours. In this time the mother may be very restless and nervous. This is a good time to get her ready for the delivery by making sure she is walked and has urinated and defecated.