That’s because they kill in different ways. Cats are more like Rogues - you get a scratch one day and then later you’re dying a slow painful death of Cat Scratch Fever, or silently end your pregnancy with Toxoplasmosis.

Dogs on the other hand are more like Barbarians, they just brute force your death in person as fast as they can.

Edit: Parrots are Bards. That is all I will say.