The meaning of dog nesting

The original meaning of the word "nesting" is to incubate eggs. The birds lie on the eggs to allow the embryos in the eggs to develop into chicks. Dog littering generally means that the dog has given birth to a litter of puppies, and the buyer buys all the puppies. For example, if there are 8 puppies in a litter, and the seller thinks it is too troublesome to sell them one by one, he will lower the price and sell all the puppies to others at once. This behavior is called littering.
Another explanation is that the dog is about to give birth, just like a hen hatching an egg, which is the process of giving birth to life.