Zohan is a year old now, and starting to display some obnoxious behavior on walks. Specifically, he lunges and barks hysterically at anyone that walks towards us. It's especially bad if the person makes eye contact, and once the behavior stops, it's very difficult get him to snap out of it. I know this "teenager" phase is challenging, but I worry he is going to become aggressive. What should I do?
I have seen his reaction around strangers coming to greet him. While it may come across as "aggressive" in some people's view, he is really being defensive - not aggressive. His defense drive (one of two key drives that a dog has innately) kicks up a notch when he is uncertain. For some dogs, when they feel uncertain about a new place or person, they go into a fearful-submissive state and other dogs go into a fear or anxiety state that shoots up their defense drive. This seems to be more like Zohan.
In order to change this reaction, you must change his perception of the situation and of the new person he will greet. Then add a little control once the perception is changed. By this, I mean that you may associate the new person (greeter) with a positive trigger for Z. For example, you may use a treat and squeaky ball that you can just carry with you whenever you are walking Zohan. When you approach a potential greeter, you ask them to hold the ball and squeak it a few times while keeping the treat in another hand. Perhaps, have the new greeter bounce it a couple of times to really spark his interest in the new person. Focusing on the ball and its motion should trigger his prey drive, whilst blocking his defense drive. Prey and Defense drive are inversely proportional. The higher the prey drive, the lower the defense drive and vice versa. So, two key things that you are doing by using an interesting toy or ball, (1) creating a more positive association with a new person and (2) increasing his prey drive, thus reducing his defense drive. Once you get Z really interested in meeting the new person and really excited, through his prey drive, to get that ball, you have him sit and stay a few feet away from you while you greet (or pretend to greet) the new person and then you give him the "ok" to greet the person. When he comes in for the ball, the greeter may then hold out the treat in a flat palm, low to the floor (since Z is a low rider ;-)). You don't want people going over his head to pet him, as most people do, because that may trigger his defense drive. So, Zohan should come in towards the greeter after you gave him the ok to go greet. The greeter has their palm flat for Z to come get his treat and make the positive association, then the ball comes out and he gets to focus on the ball and go get it (not too far - within the vicinity of the greeting). While keeping him on prey drive mode, you subdue his defense drive. Finish the exercise with lots of praise!
It is important to have several interactions like this before you even get people to pet him. This will allow for many greeting events to be positive with low to no defense triggered, and will make it easier for Zohan to make a clear and consistent association with a more positive way to greet.
Hope this helps. It is so much easier to show you all this than to write it down. Whew!