Animals have suffered more from negative language stereotyping than all the others, and demeans them so constantly that they created an environment that allows all sorts of cruelties, many too horrendous to describe!
An animal is 'it' instead of 'he' or 'she', this perpetuates our view of them as 'things' rather than individuals and is a major first step towards cutting them up for meat and leather, testing drugs/cosmetics/ household products on their bodies, and tearing off their coats for furs!!!
Those who have pets are referred to as 'owners' rather than guardians/care givers/companions, reinforcing the idea that they are property much as slaves were considered property.
***** rat
Filthy pig
Acting like an ***
***** dog
She's a *****
Ugly duckling
There's more than one way to skin a cat
Behaving like an animal
Making a monkey out of someone
Killing 2 birds with one stone
Working like a horse
You're chicken
There are many more! Please think before uttering them and tell others.