Not a rare, but I just finished explaining the origins of my red worg, Umbergore not too long ago. If I remember right there was a quest in Blade's Edge that had you vaccinate the Horde-neutral worgs in the area against the Alliance-neutral faerie dragons. This understandably made them upset, but seeing as I was in the newly-budding stage of almost-Horde-patriotism, I didn't want to kill any of the worgs.
I discovered that trapping and tranqshotting them(or something similar, it's been a long time) got rid of the buff and allowed you to vaccinate them again. I picked the worg closest to the main gate and chaintrapped him back into the village, forming this awkward rhythm of trap, tranq, vaccinate, repeat on this poor, poor critter. All of the required vaccinations later, I trapped him a final time, feigned, and let him hobble back to his post covered in bandaids.
Maybe it was the way he waddled aimlessly in circles or maybe I just felt bad, but he seemed completely out of it - understandably - and I wound up taming that specific worg not long after I turned in the quest. He remained by my side all the way to 80. I stabled him at the beginning of Cata, saying he had died of old age, but all this talk about him has reminded me that he's got quite a bit of fight in him still - he'll be 85 as soon as I can manage.
