It happens, you can't really avoid fights sometimes when you walk a dog. I have lived in a very dog heavy area for almost 32 years and there have always been a lot of large dogs, a few of which have either same sex DA issues or they will try to repel any dog "invader" from their self determined "home". most of the small ones would put a good show on, but only a couple of Jack Russel's had the nerve to just come out and get into it instantly My old Pit mix Gus was attacked by a few of these "tough guys" during his life. He had so much hair on his back of his neck and shoulders that most of the attacks didn't do any real damage to Gus, just pulling out a lot of hair, at first. The other dog, as long as I was able to get it stopped somehow before Gus would finally get angry enough to retaliate, would get away pretty clean too. One time, a JR came out of nowhere, and started pulling big wads of hair out of Gus's shoulders and neck. I was able to stop it the first time by picking up the JR and putting him on top of a shrub. He couldn't get out of it for a couple of minutes and we got the hell out before he did. The next day, he wasn't there, but about 3 days after that, he popped out of a bush and attacked instantly, but his owner showed up and grabbed him just as Gus was about to lose his temper. The JR's owners put up a no-jump fence with the top that angled in and he couldn't get out, so for the rest of Gus's life he just snarled as we went by. The only full blown all out fight he got into was when he was about 2 years old and he was jumped by a huge GSD who was asleep in a parked truck we walked by. I couldn't do much of anything as the Shepherd was trying to bite me every time I tried to get in between them. Gus finally "went off" and the GSD ended up getting chewed up badly in the first round. After Gus chewed on him a while, he decided to bail out and then his owners came out and he attacked Gus again. I guess he thought his folks were coming to help him fight. When it was all done. Gus had a couple of holes in his ears, a lot of bruises on his neck and shoulder, and the GSD had to go to the emergency vets to have a lot of stitches. It was the first real fight Gus was ever in and his skill chewing up the much larger (About the 3rd biggest GSD I ever saw) was kind of shocking. I carried one of those little air horns after that for the rest of Gus's life and through most of my next dog King's life too. I would guess that there was about 1 fight a year for the next 10 years with Gus. As he got very old, he outlived most of the dogs his own age and the new ones seemed to be slightly less aggressive. When King came along, he had zero tolerance for the tough guy dogs, and even though he didn't have the strength or bite power Gus had, he had fighting skills, was afraid of nothing that lived(no BS, he was totally fearless of any dog or person, or wild animal he came across), and was very very fast at flipping dogs over, no matter how big they were, and usually the entire fight consisted of the dog running at King, then getting flipped on their backs and King grabbing them by the throat and making some terrible sounding snarls that seemed to totally rattle the other dog. Most of the time at that point, it was over with, but a couple of times King would get his ear punched and he would chomp on the other dog. Nobody was ever seriously hurt, King didn't have the jaw power to do anything like the damage Gus could do. A risk of a fight is just part of the walking deal, it's going to happen once in a while if you have a heavy dog population.