I am not saying it couldn't be real but the picture itself looks photoshopped to me. Look around the guys head. The wolf could be real but the pic is not.
That picture's been around a while but it doesn't even raise my eyebrow. They're bigger critters than most people think.
I have no doubts that its real. I have seen some very big wolves over the years. And his other leg is behind the tail, if you look close you can see it.