I used to have a beagle with a horrible pulling problem, and the gentle leader worked wonders! It works by controlling the snout through pressure and it doesn't cause pain or discomfort. I have only heard of a few people who didn't have success with it.
Sometimes it can take a while for the dog to get used to it, but it's definitely worth it. I saw an elderly man who was getting pulled all over by his enormous English bulldog. He tried the gentle leader, and it solved the problem.
