We all love animals. But some people take it too far.
The people at PETA would like you to NOT use animal names when referring to people who have traits you don't like. They don't want you to call your terrible ex-husband a "snake". Because that would be offensive to snakes. And that child of yours that tells on his brothers and sister, don't call him a "rat" for snitching them out. That is offensive to rats.
This is not a joke. They actually have posted a list of words you can use instead of animal names. No, seriously they did.
And if you insist on calling someone who's messy a "pig", make sure there are no actual pigs around to hear you.