"To the amazement of everybody, three of them flung themselves upon Boxer"
"Boxer! Get out! Get out quickly! They're taking you to your death! Good-bye Boxer!"
Napoleon had his dogs attack Boxer because he was worried that Boxer wasn't following his rules. This relates to the theme of violence because Napoleon is using it to control the other animals.
Boxer has been sick and Napoleon has a symbolic man pick him up and take him to the slaughterhouse.This relates to the theme because Napoleon uses death to his advantage to make money off of Boxer's dead body.