My dog loves trail riding, and nails it as well! The same as many of my dog partnered riding mates, bridle ways what ever. I dont take him to trails so often, but when I do, I usually see other dogs.
I agree a badly trained dog could cause an accident, but then so could a badly trained mountain biker!
If you ride around a corner quickly, as we all do, then theres always a possibility of hitting something, Ive had Badgers and foxes run out on me, SHOULD WE BAN FOXES AND BADGERS FROM TRAIL CENTRES AS WELL?? The climax trail in Machynlleth has a wild ram, that stands about 4 foot tall at the shoulders and has foot long horns! Good luck if you run into him 😛
Heres a video of me a mate and the dogs having fun 😀
[video]http://www.youtube.com/watch?v=liMcNzcZEkg[/video]