When it was all over, the remaining animals, except for the pigs and dogs, crept away in a body. They were shaken and miserable. They did not know which was more shocking – the treachery of the animals who had leagued themselves with Snowball, or the cruel retribution they had just witnessed…Since Jones had left the farm, until today, no animal had killed another animal. Not even a rat had been killed.

George Orwell

Animal Farm. Chapter 7. The animals are horrified at this turn of events, of animals being killed by animals in Napoleon’s wave of terror.