To stop a dog from lunging, head halters can be used if utilized correctly, and they are a much safer way to manage lunging while training a pup to act properly on leash. I recommend using two leashes – one clipped to the head halter, the other to the dog’s regular collar. If he lunges, you can absorb the shock with the regular collar, then use gentle pressure on the head halter to turn him away from the object of his attention. Then, of course, you must reward the appropriate behavior with a reward marker, followed by a yummy treat. If you use the halter without the marker and treat, you are managing his behavior, but not training him to offer you the correct behavior voluntarily. It’s also important to understand why he’s lunging, and to work on training him out of that behavior as well. Instead, teach him a rewarding, incompatible behavior – such as looking at you with rapt attention – using Clicks and tasty treats, so he associates the approach of others with really wonderful stuff coming from you. If he is lunging at other dogs because he wants to go play with them, teach him that the way to get to go play with other dogs is to be calm and sit looking up at you.