my 3 year 5 month old boy shook.hands with my neighbours doc the contact was minimum. the dog was in my neighbours hand and the dogs nails were grinded. it's a fully vaccinated dog. but after the handshake I noticed a very small scratch at the back of his palm i am not sure if it was from the dog or was it from an injury he had encountered from falling while walking just before meeting the dog. What should I do in such a case. if it's from a fully vaccinated dog then is there any risk