The Realization of Cats
Cats are regarded as low on the Buddhist scale of realization, because they are so carnivorous, so lacking in apparent compassion, and so subject to their desires. One Pure-Land tradition at least holds that the cat, alone among animals, doesn't get to appear in the pure lands.
But cats don't need to cultivate detachment from their desires: they are their desires. If any creature has achieved one-pointed attention, it's a hunting cat.
Possibly you're reborn as a cat if your realization of emptiness outstrips your accomplishment of compassion by too much: I have known, I think, highly accomplished meditators who are going to be toying with mice in their next lives, and snapping little mouse necks with relish.