It's something we hope we never experience, but at some point are likely too, anyway: the high-speed intersection of running dog and barbed-wire fence. Or equally dangerous, running dog and cattle guard. But how to negotiate fences and cattle guards generally isn't something people specifically train for. I know I never have, but what I have done with all my dogs is introduce them to fences and cattle guards as puppies and let them figure out on their own the best way to negotiate their way. I've found that with enough practice in a controlled environment, eventually all my dogs learn how to get through a fence or around a guard without trying to run straight through it.