If your dog is growling and lunging at other dogs while you're out on walks, there are a few things you can do to help correct the behavior. First, make sure that your dog is getting plenty of exercise and mental stimulation during the day - a tired dog is a well-behaved dog. If your dog is already getting plenty of exercise, try adding some training into the mix to give his brain something to work on. Secondly, keep up with your socialization efforts - expose your dog to as many different types of people and animals as possible so that he learns to be comfortable around them. Finally, if all else fails, consult with a professional trainer or behaviorist who can help you troubleshoot the problem.