The dog's ability to defend it's owner has always been considered one of the most important dog's merits if not the most important one. Since olden times, people needed such dogs that will defend them and their possession against any intruder including not only strange people but also wild beasts.
The more modern human society is, the more it restricts aggression in dogs and so it often happens, that many dogs are unobservant and literally unable to defend their owners. But why is it so?
The first reason for this is the modern way of dog training. Dogs are mainly using their prey drive and not the fighting one, they use to bite protective sleeves only and not body bite suits, they use to only train at a training area and not in natural environment like the possession that they guard, town streets, train or buss and similarly.
I have seen dogs that were performing on the bite sleeve very well, but as soon as the helper put the sleeve down, they began to be friendly toward him and were not able to bite him even if he tried to tease them.
I have been training dogs since 10 years and I have many experiences. I was also doing a night police work and other activities on this field. And I tell you that the modern sporting dog training is no sufficient way to make the dog a real defender. So if you need to have one, what should you do?
As a golden rule says it, every proper defender must consider every stranger a possible danger to it's master. That is why the protection work training must be performed using strange people, which the dog does not know. It is a mistake to have only one or two helpers, whom the dog knows well.
You should alternate training areas, your dog should bite not only normal protective sleeve but also hidden sleeve and hidden body bite suit, it should be confronted with many offenders (helpers), both male and female, dressed in normal clothes to make the situation look naturally and regularly do such a training in any environment - both at home, on the garden, on the street, in the buss etc.
It is however expensive to pay more professional helpers, so the majority of people will do with a couple of friends or strangers who will, now and then, tease the dog, when it will be muzzled and on the leash. But who wants to really have a good defender, he has to train it on hidden body bite suit and in every possible environment with a lot of helpers which alternate.