The final challenge in last night's episode of Greatest American Dog was rather shocking! In an intensified agility-type course, it ended with a doggy zip line . . . whoa! Even if you don't agree with J.D.'s training methods, he and Galaxy did an amazing job here, probably due in part to her training.I can say with near certainty that my scaredy dog would never step off a platform that high, not even if I were covered head-to-toe in peanut butter. I'm assuming most of us don't have the professionals or equipment on hand to try a stunt like this at home (nor would we ever want to), so think hypothetically here – would your dog ever complete it?