FIRST MURDERER: We are men, my liege.
MACBETH: Ay, in the catalogue ye go for men,
As hounds and greyhounds, mongrels, spaniels, curs,
Shoughs, water-rugs, and demi-wolves are clept
All by the name of dogs.
– William Shakespeare
Macbeth, Act 3, Scene 1. Macbeth is trying to persuade and manipulate the murderers into killing Banquo and his boy Fleance. Here he reduces the humanity of the murderers to the level of animals. In a metaphor he compares the different kinds of men to different types of dogs, each with its own skills.