As veterinarians, a common behavior question we hear from owners is how to stop their dogs from pulling on the leash when being walked. We highly recommend the Gentle Leader headcollar.
Traditional dog collars fit around the neck in a circle, so that when your dog pulls against the collar, it puts pressure against his trachea (windpipe), making it harder for him to breathe. The dog's reaction is to pull away from the unpleasant sensation, and you end up being dragged along by a coughing, gagging dog. Not a pleasant experience for either of you.
When a dog wearing a properly fitted Gentle Leader Headcollar pulls against the leash, the headcollar puts gentle but firm pressure not on the trachea, but against the muzzle and the back of the neck just below the base of the skull. Dogs respond to these signals because they are similar to the ones they naturally use to communicate with each other. When the dog stops pulling, the leash is slack, there is no pressure, and he is rewarded for his good behavior. At the same time, the owner should be using a verbal command such as, "Look at me" and giving the dog treats as they are walking along. The goal is that with practice, when another dog, a squirrel, a bicycle, etc. goes by, the dog will stay focused on the owner, rather than reacting to outside stimuli and pulling on the leash.
The other key to the Gentle Leader's success is that it allows you to maintain control over the dog's head. The leash attaches to the Gentle Leader headcollar below the jaw, rather than at the back of the neck as with traditional collars. With the Gentle Leader, if your dog lunges against the leash you can easily turn his head to the side - redirecting him, and encouraging him to shift his focus back to you and what you are asking him to do. As an example, if your dog lunges at another dog while you are walking, you can turn your dog's head - with the rest of his body automatically following - away from the other dog, so that your dog's hind end is now facing the other dog and they are not looking each other in the eye. This helps calm both dogs down, and you can now ask your dog to sit and reward him for it, redirecting his attention onto you. Good job!