So I have been noticing these scratch marks on my son's hands repeatedly this week and I thought he…

So I have been noticing these scratch marks on my son's hands repeatedly this week and I thought he was either getting into things he's not suppose too or god forbid the babysitter handled him wrong or what not. Come to find out my dog has been bitting him, and leaving these marks. Not the full blown attacking him but more of the play bitting thing. My dog is almost 4 years old and never understood the concept of no biting. Usually it's whatever and we go about our business but I am not ok with these scratches on Aydan. Aydan finds it hilarious and loves playing with Kobe and never cries or yells when Kobe nips him because it's not painful or even long. I'd hate to get rid of the dog but the biting and marking up Aydan isn't ok either and can't seperate the too because Aydan likes playing with him and Kobe likes the fact that the baby always taste like banana. Any ideas?