My 14 week old puppy consistently attacks my 11 year old son's shoes every day, multiple times. If he walks by, the puppy will attack his feet by lunging, biting and shaking. He has stopped the behavior with the rest of the family. Nothing has worked to deter him from this behavior. My son is very good, patient and loyal to him. We have tried many things from the book and puppy classes. Could it simply be red shoe laces? Please help! I don't know how much more bloodshed we can take!