You must have summoned her from one HECK of a party!
Seen that before on a hunter pet I think (lol at 19 days remaining though).
I think you can only get rid of it by killing the pet somehow.Duel maybe?
Lol I had this once I think I fixed it by summoning a new pet (as you summon a pet, I THINK the duration goes down.) Simply end the cast when it hits zero.
Note: This could be incorrect, it happened a long time ago to me, and I remmeber looking that up and somehow fixing it sometime after.