Does the mother eat sac after a puppy is born?

Yes, after giving birth, the mother dog (dam) will often eat the afterbirth (placenta). This is normal behavior and is referred to as "placentophagy." While it may seem strange, there are several reasons why dogs do this:

1. Nutritional Benefits: The placenta is rich in nutrients such as proteins, hormones, and vitamins. By eating the placenta, the mother dog is able to quickly replenish essential nutrients that were depleted during pregnancy and labor.

2. Hormonal Regulation: The placenta contains hormones that can help to regulate the mother's reproductive system and promote lactation. By consuming the placenta, the mother dog's body can receive these hormonal signals and adjust accordingly.

3. Instinctual Behavior: Eating the afterbirth is an instinctive behavior that is seen in many mammals, including dogs. It is believed that this behavior evolved as a way for the mother to keep the birthing area clean and reduce the risk of attracting predators.

4. Bonding with Puppies: Consuming the placenta also releases oxytocin, a hormone associated with maternal bonding and milk production. This can strengthen the bond between the mother and her newborn puppies.

While eating the placenta is generally harmless, excessive consumption may lead to digestive issues such as diarrhea. Therefore, it's important to monitor the mother dog's behavior and ensure she does not over-consume the afterbirth.