Very soon after the Rebellion, Napoleon took the week-old puppies from Jessie and Bluebell, claiming that he would personally educate them. In reality, he was training them to obey him. In the final meeting, he reveals them to the animals, by giving them the signal to attack Snowball. They chased him from the farm, for good. Napoleon then used them to begin his reign of terror. Later on, they slaughter any threats to Napoleon, before the farm animals, to display Napoleon's power. They slaughter The Four Young Pigs, 3 hens, 3 sheep and a goose. They even attempt to kill Boxer, but to no avail.
They are the counterparts of the Soviet secret police.