According to PetMD, dogs give birth in three stages. In stage one, uterine contractions begin, and the cervix relaxes, rupturing the chorioallantoic sac. In stage two, uterine contractions push the puppies through the birthing canal. Finally, the fetal membranes are delivered in the third stage.
PetMD reports that the average duration of a canine delivery is less than four hours. On average, puppies are delivered between 20 to 60 minutes apart. However, it takes up to three hours in some instances. Not every delivery occurs in three distinct stages, and it is normal for stage two and stage three to occur simultaneously. Some dogs deliver several puppies followed by several fetal membranes.
According to PetMD, dogs often give birth without assistance. However, seek help from a veterinarian if the birth is delayed or if the female appears to be in pain. If the puppies are delivered more than two hours apart, there are 30 minutes of contractions without expelling a puppy or the labor lasts more than four hours, contact a veterinarian immediately as these are symptoms of dystocia. Dystocia is the medical term for a difficult birth. If your dog is pregnant, create a plan with your veterinarian. Watch for nesting behaviors that indicate your dog is preparing to go into labor to be ready for the birth.