I was actually thinking of Belle Remings and Lyllwen Green when I mentioned the "considerate" owners.
Here is another thought: what if the "partner" of the dragon gets suspended for a time (increasing time as more incidents occur, ban if the problem doesn't get fixed) when the dragon goes wild?
If you knew you would get suspended for three days if your dragon went wild and killed anything, I think you would make darn sure your dragon was well fed and not parked at the Bank. I know I would.
I also don't think this should just be for dragons. Lesser wyrms poison, phase spiders cast, drakes do damage, frost drakes can kill (not me, mind you, but a freshman).
This may seem harsh, but think about it: if you take it upon yourself to kill owned henchies or a fellow player, what happens to you? The same argument could be made for someone being careless enough to not take care of their dragon or other animals.
More random thoughts on an early Wednesday morning...