1. Stage 1

2. The first stage of labor typically begins 24 hours after the dog's rectal temperature drops from around 101 degrees F to 98 or 99 degrees F. The mother dog will appear anxious and restless and may look for a place to hide, retreating behind furniture or into a closet. She will commonly begin "nesting"--pulling towels and fabric into a pile on the floor where she can give birth. She may refuse food, start panting and pacing, and may vomit. Although there are no visible contractions at this point, the cervix is beginning to soften and dilate.
   
   Stage 1 normally lasts 6 to 12 hours, and the cervix will be completely dilated at the end of it. Veterinary help is necessary if the dog has not produced a puppy within 24 hours of beginning this stage of labor.

   Stage 2

3. The second stage starts when the first puppy enters the birth canal and the mother begins active contractions to give birth. Heavy, strong abdominal spasms are visible by this time, and the dog will either lie down or rest on one side of her haunches to expose her vulva. She may vocalize as the contractions become stronger and the puppy's amniotic sac emerges from her vulva. Usually, one large contraction will push the puppy completely out and the mother will begin licking the sac away from its face within seconds.
   
   It is considered a veterinary emergency if the dog does not whelp (birth) the first puppy within 2 hours of beginning this stage. The mother may rest after the birth of the first puppy; if her resting period lasts longer than 4 hours without another puppy being born, veterinary assistance is needed.

   Stage 3

4. The delivery of the placenta (the organ that provides nutrition to the puppy while in the uterus) indicates the onset of stage three labor. This normally occurs 5 to 10 minutes after the birth of the puppy. If several puppies are delivered in rapid succession, several placentas may be delivered at one time. The mother dog usually eats the placenta, which then releases the hormone oxytocin into her system and allows her colostrum to flow. There should be one placenta per puppy; if not all of the placentas are delivered, a veterinarian will need to intervene to prevent infection.

   Whelping

5. The mother dog will repeat stages two and three until all of the puppies are born. She may rest between each birth or have several puppies at one time and then rest. Typically, each puppy will begin nursing directly after it is born, and the mother will clean and lick her newborns even as she is contracting for the next birth.
   

References