In the Fallout universe I think anything is possible. When it comes to real life though, I think we're doomed as a species to being the only truly intelligent lifeforms.
I'm not sure I'd like to know what an animal was thinking anyway...
We are animals... (just a pet peeve of mine when people separate us; the biology student in me speaking)
I'm sure some non-human lifeform out there in the real universe is "intellegent", though, but where are the little buggers?
As for what a non-human animal thinks, it's probably the same thing as a human animal:
six-eating-more six-more eating-six, again-video games