I just wanted to add, please be sure to teach your son on how to handle a puppy and proper ways to approach a dog. Just from personal experience, I've noticed that boys can be little rougher than girls would be. Since you've decided on a yorkie (and for any small breed), if the puppy ends up being very small (2-5 lbs), their body will be fragile to a point.
Having a dog is a lot of work but the love and joy you get back is twice as much!
