When i was leveling in Outlands i can across a mounted Orc.
The first time i fought the Orc it dismounted and the worg it was riding joined in the fight.
The second time i cheapshotted the Orc but the mount despawned and i only had to fight the orc.
I retried this technique and it removed the worg every time.
I found a Human on a horse and had exact same results.
Not the most helpful exploit but it can come in handy.