Jeff Corwin just hosted a very good special on wolves a while ago.
I watched that, it was a good episode. Wolves have always been one of my passions to see and learn about. They are such wonderful creatures.

I agree that they kill the dogs due to a threat in their territory, not to hunt for food. But they also aren't wasteful animals so they will take advantage of fresh meat. Also the dogs may have been eaten too by scavengers.