I increased the droprate of the canines ever so slightly, though they were at the same rate as the noble rings previously, not sure why you saw them as being more uncommon. This should take effect next server reboot. I'm also going to be increasing the xp for turning them in slightly, which will take effect as soon as I can get the quest updated serverside.
Edit: It should be updated with the new exp values. I went ahead and updated the xp rewarded across the board for all three of the quests he offers.