My dog had a very high "prey drive". She heeled perfectly....until she focused on a bird, cat, dog, leaf....(the list goes on). We put her on a prong (with the help of our trainer) and it was a MIRACLE
. We tried the gentle leader harness, but heeling wasn't her issue. She needed a quick correction, which the prong collar did. After the first week, she learned to control herself; now most times a "leave-it" with slight pressure will work.
You need to "correct" as soon as your dog focuses, or tenses up. Timing is very important with the prong. Good luck!
