Has anyone ever used the gentle leader harnesses? We used to use the head collar but it gave Fredo a rash. He has been doing very well on the leash, however when we see another dog or person he starts pulling like crazy and the martingale collar was not doing the trick. I bought the stop pulling harness and so far so good. I was just wondering if anyone has had any success w/ it and if anyone has any tips regarding it's use. Thanks.