A dog's normal temperature is 101 or 102. In late pregnancy it will run below normal, around 100. Within 24 hours before delivery it drops to 97 or 98. Toward the end of the pregnancy, the dog's abdomen will balloon out, her mammary glands will enlarge and may drip milk, and she will display nesting behavior. However, the only sure sign of impending labor is the drop in rectal temperature.
Labor begins with contractions of the uterus and abdominal muscles.
The amniotic sac will protrude, followed by a pup and placental membranes. Puppies are generally born in pairs, maybe 15 minutes apart, followed by a rest period that lasts up to an hour or, in large litters, even longer. The mother may take a break and walk around during this rest time. Each pup is delivered enclosed in an amniotic sac that the mother breaks open. The mother then chews the umbilical cord and cleans the pup.