We had a scare with Cody as a pup, I have a kennel on the patio, chain link type, I had put him in the kennel and when I came back I heard him crying and ran out there and his collar was stuck at the bottom of the kennel on one of the "loops" the wire makes. I think he may have been laying next to it and when he heard me drive up the collar caught when he got up. After that the only time they had a collar on was when they were on leash! At home they never wore collars any more! Like Super G said I think discouraging standing against fence, counters whatever, they never tried to jump the fence, same with digging, I always did the at at sound or a sharp " hey" and we never had a problem. We have 6 foot chain link with railroad ties that line the fence, I had put like chicken wire down under the railroad ties so we never had an escape! But the neighbors chihuahua squeezed in between the gate poles!! I drove a piece of pipe down between those and that stopped that! Like others have said I don't think you could have chased the shepherds off with a stick, they never seemed to want to get out! I agree too with maybe not training jumping in your yard!