Do you ignore bad behavior in hopes it will just go away?
Whenever you have a dog who growls, barks, snarls, or tries to lunge through a fence at another person or animal and you ignore it, you are creating a monster. Not correcting the unwanted or bad behavior will teach the dog that this behavior is 100% acceptable. It will only get worse over time and not better. Allowing your dog to continue with this bad behavior could result in someone or another animal getting bit. When a dog misbehaves in this manner, immediately correct his actions in a calm but stern voice, or a calm but stern motion. Overtime this will teach him that these are unacceptable behaviors and you will not allow it. He will know you are boss.