I'm a firm believer in controling the over population of dogs and cats. Additionally, what I read in your message is that your little dog is out of control; yes, you should neuter him 1st thing. Then getting working on 'working' him. Chiuahuas ( Like most breeds) were bred for a particular job, he needs to be kept busy . Walk him, play with him, teach him to do stuff. He'll be happier, you'll be happier. We all fall for cutest dog we see, but most people don't consider the temperment of the breed,or our own limitations , it's human nature. I've always had large dogs, Labs, Shepards... the last time I was in the market for a new pet , I gave it some thought... I have a Greyhound now, large, non-agressive, inside, cookie eating dog, no barking, shedding digging,or biting.... spend some time teaching him a job....:)