My 6 mo old shih tzu - Bailey - has started to lift leg and mark everything accessable. He did it a few times last month and I had already scheduled his neutering so we thought it might help him! Not really, he is now lifting more and I have to constantly watch him and correct him when I can. I have 2 cats that I think he is defining his territory at this point. They have been playing lately but more agressively and now he came up with a new one..he went into their litter box and ate the feces! I wasn't able to catch him so now I keep him away from where it is. I am sure this is all behavioral !