Hi, My server was started with the beta 1.8.1 version and since the first date, we never seen one wolf in the server. I thought it was a bukkit bug with the 1.8.1 version. Now my server was updated to 1.0 version and still no wolves. Am I alone or does it happen also to someone else?
I had this same problem before, some seeds just DON'T spawn them. I would recommend trying a new seed or getting a mod (CommandBook) that allows you to spawn them by hand.
With the 1.0 update with keep some old region. Now wolves spawn in new region (generated with 1.0 generator) but in old region wolves don't spawn. And with the update our seed seems to have change.