For a litter of 4-6 puppies, the average time is 6-8 hours, but larger litters can take considerably longer. Intervals between puppies are usually 5-30 minutes long. If you suspect the mother has not finished delivering all her puppies and she rests for more than 4 hours, or if she actively strains for 30-60 minutes without delivering a puppy, notify your vet without delay. Make sure that all puppies are delivered with a placenta following! A retained placenta can lead to death. You may wish to give an oxytocin shot after the last puppy is born to clear out her uterus.