It never occurred to me that a dog could jump a 6ft fence. That is, until I caught the dog across the street doing it. He would wait for his owners to leave for work and then he would take a leap and pull himself the rest of the way over. The more amazing part was how how he completely cleared the fence from the outside, to get back in his yard, just before his owners got home from work.
I feel sort of bad that I never told the owners but I was in awe of what the dog was doing and he never went around the neighborhood harassing small animals or kids. He was very sweet. The neighbors moved.
Then, a young fellow moved in next door and he owned a black pit bull. She was also very sweet. One day, I opened my door and there she was, on my porch. I walked her back to my neighbor's side of the house, opened the gate and she went back inside the yard. Something told that was not going to last. I hid, just inside my front door, with it opened a crack. Sure enough, within minutes, there she was going over the 6ft fence.
When my next-door neighbor got home, I told him what had happened. Turns out he had installed some wire contraption all around the top of the fence to keep her from going over - except for a small 3ft bit. That small 3ft bit was exactly where she was going over. He fixed the wiring thing and she never did it again.
Here's some youtube videos of dogs jumping fences:
http://www.youtube.com/watch?v=JgHa8aBVhmwhttp://www.youtube.com/watch?v=MEjOdQlp_t0&feature=relatedhttp://www.youtube.com/watch?v=JizHR37V5ms