Vela had told me about this incident and I just wanted to say I am so very sorry Anna. I can only imagine how traumatic this all has been, it will take time to heal emotionally as well as physically. Yes mastiffs have very powerful jaws and a quick bite from a big boy like that can certainly cause more damage than a more average sized dog. They have a naturally powerful bite and big jaws. I think in a fight like that, as others have said, the instincts kick in and all they know is that something is holding/hindering/grabbing them and they are suddenly feeling more vulnerable. I think you've been given good advice on feeding separately etc. I know your nerves must be shattered by this, not to mention the physical pain. I hope you have found some comfort and support in most of the posts here. I also feel your post is a good and important reminder to all of us to be careful in how we react when something like this happens, I only hope I will never be in that situation, but I know it could happen to any of us with multiple dogs.