If you're watching your dog give birth to puppies, keeping track of the placentas might not be the first thing on your mind. It's important, however, because any whole or partial placentas remaining within the mother dog after delivery can cause serious illness, even death.
Also known as the afterbirth, the placenta nourishes the fetal puppy in the uterus. While the fetus grows, it is completely encircled by its own placenta. As the puppy starts passing through the birth canal, it's still enclosed by the placenta, but during the birth process the placenta breaks and is expelled after the birth.
Whelping, the canine term for the birth process, occurs in three stages. The initial stage of early labor can last 12 hours, as mild contractions grow stronger. The second stage consists of the actual delivery of the puppies. The third stage is passing of the placenta. The afterbirth might pass with each individual puppy, usually within 15 minutes of delivery. If the mother has a few puppies in rapid succession, those placentas may come out en masse. The final placenta should appear within half an hour of the last puppy's birth.
Don't freak out if the mother dog starts eating the placentas. It's in her nature to do that. Hormones contained in the placenta aid in milk production, but consuming the placenta can cause diarrhea in the mother for a few days. Just make sure you keep track of the number of placentas so you know one emerged for each puppy, whether the mother ate it or not.
Any sections of the afterbirth still inside the birth canal generally pass within two days of whelping. As the mother dog defecates, the muscle action also helps propel afterbirth remnants out. If the mother dog develops a greenish, smelly discharge within two days after delivery, take her to the vet for an examination. She might also develop a fever, stop eating and appear ill. Your vet might give your dog oxytocin, a medication that stimulates uterine contractions to expel the placenta. If that doesn't work, surgery might be necessary to extract the placenta. If the uterus is already infected, spaying might be required to save the dog. During this time, you must bottle-feed the puppies every few hours with canine milk replacer.