I have a pittbull and a lab. the lab has been trained for years to stay in the yard with not zappy collar. The pitt was a little harder due to all the moving i did, and she did’t wana learn to stay in the yard. So i got a zappy collar, even the biggest one didn’t really phase the pitbull. I learned that i just had to train her the old fashioned way, by the fist. And you can call me a bad person. But after a hard few months, she has had 2 years of freedom. They live in the garage that is attached to the house, and the door is open all day for them. They get to roam around, lay in the grass out front and chase each other like retards. Sometimes the most humane thing you can do is hit your dog, how do you think police/military dogs are trained. One thing that i realized from my friends experiance with electric fences, if your dog is running to chase something, they will be threw the 6 foot fence line so fast that they will only get like one zap, and then they have to get zapped to get back in, so they won’t and then your screwed. So all in all, train the dog.