Hello , my blue red heeler -because it has both blue and red- was found on the side of the road with his sister I adopted him and he is a very good dog inside but outside he barks mean and snaps at my neighbors kids heels.. I worry because we live so close to people and I hate him having to stay on a rope outside how do I fix this violent behavior. Also note that I got him very young 6months and he is now 2 years old so it wasn't lack of training as a younger dog..