Fallen Heads Under Heels

Or that would be the case if he had any heels. Do cats have heels? I suppose if they did, it would be at the back of his hind paws, as ours are on our feet. But if Miko has heels on his hind paws, then he'd have them on his fore paws, which means we'd probably have heels on our palms??

This is so confusing. Maybe the phrase doesn't apply to animals.