My dogs definitely dream. They kick, twitch, growl, move their mouths, make their whiskers twitch, and make these low throaty noises, and it seems to be during REM sleep just like humans do because if I look at them closely I can see their eyes moving under closed lids. This fascinates me. I want to know what they're dreaming about. Whatever it is, it must be stimulating. Doesn't seem to last for very long, though. One of my dogs makes this strange whooping/howling noise during some phase of her dreams.