In Chapter 3, two of the dogs, Jessie and Bluebell, give birth to 9 puppies between them. Napoleon immediately takes the puppies and says that he will be responsible for them. He takes them away and people pretty much forget about them.
The reason that the puppies are so important to him is that he is going to train them to be completely loyal to him. They will end up being his "enforcers." Later in the book, they will be the ones who scare everyone else into obeying Napoleon.
So it seems that in Chapter 3, Napoleon is already planning ahead and seeing that he will need to intimidate people later on.