i'd still put it to passive, just to be safe.  there are certain beasties that could trigger your panther (i'm guessing) and you don't need that headache. can't you have 3 pets or something?  variety! get some other shit too.  My faves were a black lion from the barrens and i think a boar - it had a rad charge.  think i also had a diseased bear from later in the game.
loaded up Oblivion again to try this total conversion mod called Nehrim from germans .  So far it's really good.  Instead of the generic world that Oblivion kinda had, everything in this total conversion was planned out and it really shows.  Also, rad german-engrish.
edit: just remembered i had an awesome pink flamingo too - that was from cow-people land (forget - taurens, ya) - back in the day pet stats weren't normalized like they eventually were, so it actually made a difference if you sought out hard to find pets.  good ol bad days