I think underground fences are effective to a degree, but I don't know anyone that has one that would say they are 100% effective. My neighbors had a lab, and it would cross the fence occasionally. Another set of neighbors had a boxer, and it never went outside the fence. The only difference I know of is that the boxer was trained as a puppy to the fence. I tried a fence once when my dogs were about 8, and you would have thought I killed them when it buzzed them the first time. I never put the collar on them again, and felt guilty for weeks
