Dogs which can be so dangerous that they can rip people to pieces and kill them.
That's any dog.
It's not the size of the dog it's the size of the problem that counts.
Training and consistency is not the issue.
Yes it is people allow their dog to take leadership and be the dominant one and don't even realize they are doing it through lack of guidance.
We had a dobie come to us once she wants it to learn agility.
After an hour with the dog we couldn't do nothing with it, She then told us it had been a guard dog since a young age left in a yard.
We sent her away telling her the dog needs to know who it's leader is and build a bond with the dog before you can attempt doing agility.
The issue is that those dogs are designed to be dangerous.
No dog is designed to be dangerous in their own pack it is a laid back placid animal.
It's only when brought into the human world the problems start.
A dog is still an animal and no matter how much training they can turn like the flick of a switch.
Same as a human can if threatened or bullied.
chapeau
If a dog can be relied on to 'guard' their home then they shouldn't be left alone with four other dogs and a child who is eating. Five dogs are a pack and you will get pack mentality which is not desirable in a home setting.
Dogs are predators and scavengers and if starved or are not shown the boundaries on food it will grab for food as it's precious to them.
That's why chicken/cheese etc is always used in training cause it will gain their attention and a dog will return.
2 dogs are a pack and one will always take hierarchy over the other
a pack without a leader and boundaries will become confused, unstable and in constant conflict.
Most pet dogs will not 'guard' their home using lethal violence, they might bark, but if they are the sort of dog who would kill somebody coming onto the property then they need locking up when people are around. In fact they really shouldn't be pets.
There again it comes back to a human error of not being shown boundaries.
My dog was first bred as a guard dog but over the yrs it gets bred out of them now they are the most dopiest dogs going but will still stand their ground if need be.
Even taking your dog for a walk the dog will look to you to be the hierarchy but in most cases this is the opposite.
Dogs that walk on extendable leads are the hierarchy.
Dogs that walk in front are the hierarchy.
All human errors.