The bottom line is that all dogs, even the most timid ones, have a point where they will act out to another dog that is invading their space. If your dog is well trained and leashed then you have nothing to fear as far as his behavior goes. The dog who is left to roam and the master who thinks everybody should tolerate his dog, are the problems. They invade your and your dogs space. They create bad situations.I never met a dog I didn't like, but I have met alot of ignorant dog owners who I do not care for. While my dog is not perfect he is well trained. He will approach other dogs and people if he gets the chance,and he will do so in a very nonagressive manner.He rarely gets the chance because I usually have him on a lead or I am right there to correct him before he ever makes a move. If he invades another dogs space and there is a dog fight or if he goes to another person and that angers the person for any reason it is 100% my fault and I will do whatever I have to in order to correct the situation. If it is the other way around it is the other guys fault, 100%, And I will do whatever I must to correct the situation. Most of my encounters have been minor but We must all realize that any encounter by two dogs protecting what is theirs can turn into a disastor in a hell of a hurry. Truth is in all dog encounters it is the owner of the dog who initiates an attack who is at fault because he has no control over his animal. As far as putting a dog on a gentile leader goes, "I think that a gentile leader is a good training aid when you are teaching a dog to heal and to ignore other dogs and distractions as you walk him, But if another dog ,running at large, threatens my dog. I will do what I can to stop the problem including turning Copper loose to defend himself if need be. I will not control him with a gentile leader or in any other way if he is in harms way.JMHO