Well here's a nice new pic of the big werewulffie herself. I can imagine her doing this under two reasons: The first is what Toughset said she could be doing that she likes to workout at night and does this by doing lifts with the biggest tree she can find and do presses. My impression is that she could be doing that while finding some asshole hunters was going to do the drop and run on some innocent dog using a game of fetch as an excuse to make a run for it before it comes back.
Being a fellow canine, Sabrina takes it upon herself to return the favor and approach the hunters with over a thousand tons of redwood screaming "Fetch This Assholes!" before throwing it and watching the hunters run from the rolling three before comically flying off into a lake.