I was once "prey" for three dogs who knew how to hunt as a pack. I was mountain biking and the dog owner had let his animals run loose. Two were keeping me busy upfront while the Alpha circled around from behind. Yelling was not working. A swinging camelback helped keep some distance until the red faced owner finally showed up. I am 6' 3" and 230 lbs. The dogs seemed very intent on doing some damage. The owner was very apologetic, but this could have been a really bad situation-for me! A smaller less aggressive person would have suffered.