Yes sled dogs are trained, considering they are TRAINED to pull forward, turn and stop when given a command. As far as the original post, I can say from first hand experience that COs can be trained although they do seem to tire of it quickly and choose not see the point, in a way. As far as my understanding of LGD work, they need little to no training in order to do their job of guarding. They do, however, need guidance in order to LEARN manners around the stock and those people who are acceptable to be present.