Figured out this little exploit the hard way. I was in the arena on my rogue and tried to sap another char on the hog, it hit, but he was still able to move around freely.
I will try this in a duel when my friend logs on. I will also try a warlocks fear to see if it is uneffected. Will try to upload some pictures asap. If someone here has a hog or a friend that is on that does, you could try to confirm in duels.