well apart from foxes we don't have any of those scary animals you listed in australia! Lol! I've seen lots of harmless animals while trail riding like kangaroos, wallabys, lizzards, goannas, rabbits, rats and mice. I've come across a few snakes but most of the time they just run away and I just keep my distance from them. I don't think foxes would do much, I think they would just run away. I have come across a pretty scary looking dog but I saw it before I got close so I just turned around. Once I heard a really scary growling kinda noise in the bush right next to me and I just turned around and bolted! Lol! That was scary!!! To answer your question, I would just turn and run! Im not sure if its the right thing to do but I would just do that without even thinking!