I don't think you need to be concerned but I definetly would not allow that type of behaviour to continue. No mouth on skin is my motto and you as a parent need to be there to reinfore that along with making sure your child is giving the dog the same respect.
Your dog is still a puppy and was probably just playing but a childs skin (even an adult skin) is no match for those teeth and accidents can happen so it is better to teach this now than be sorry later. NO rough housing with the dog that means everyone in the family.
Your dog is still a puppy and was probably just playing but a childs skin (even an adult skin) is no match for those teeth and accidents can happen so it is better to teach this now than be sorry later. NO rough housing with the dog that means everyone in the family.