I agree with all the other posts. I have 2 big male almost 9 months old English Mastiffs and 4 kids, ranging in ages of 10 years to 4 years old And number one rule is DO NOT run with food. It is a natural instinct to chase something that is running and with food. My boys used to fight for top spot in the family. They will have their fights But My boys know if Mom speaks we better stop. You have to be in control or a big dog will walk all over you. Take him to classes. It will help him learn that he is not top dog. plus good bonding for you and pup.
Your breeder is sick for recommending putting the dog down. He is still young and easily trained. Good luck and keep us posted
Matt and Murphy- Born March 18/08
AHHHH They are a year old already!!!!