i have had mixwd experience with the original invisible fence, the key is to make sure that the dog never gets the chance to run through the fence, once they learn that they can get through the fence forget it. i have had three dogs with the fence, the first two did well, one of the dogs died and i got a lab, that bozo would run right through, never think about it, then he taught the other dog to run through. so now the fence is shut off. i even put two collars on the lab, he still ran through the fence, one day i came home and he was sitting in the shock zone, with the collar beeping and his neck twitching from the shock and wagging his tail as he was glad to see me, go figure!!!!
alex