LOL He was trying to be dominant over your son...It's funny as my s-i-l has a yorkie..We were all up in Illinois visiting my mom about 3 years ago..My best friend was over at Moms too sitting on the couch by me talking..well I was really tired and really was ready for my friend to leave so I could go to bed..Bailey(my s-i-l's yorkie) got up on my friend and peed on her shirt....
She said well, guess I better get going, have to go home and change my shirt..