People are always asking if it's okay to train a house dog into a guard dog or protection dog. Sure, there's no one to stop you from doing so, but we have to say no—it isn't at all recommended to train your pet dog yourself, especially if you're not a licensed instructor and you don't have the appropriate environment to do the training in. Leave it to the guys who know how to do their jobs.
Training a dog to become guard dog or a protection dog is a long and arduous process. It takes months, even years, and lots of patience. There's a reason why dog training is a profession; it takes something else, a special kind of dedication and love for the animal, to be able to train a dog properly.
Training a dog in your backyard is a waste of time and won't amount to anything good. Proper guard dog and protection dog training has got a lot to do with the dog's environment and surroundings. For instance, it won't do any good to expose a guard dog in training to large open areas for long periods of time. Why not? Confining a dog helps establish early on a deeper sense of its territorial instincts, and that's something you want in a guard dog. Poorly trained guard dogs often can't tell the difference between a passerby and an intruder.
Breed is also a huge factor in the equation. Not every dog is cut out to be a guard dog or a protection dog. To make it worse, not all pups from an appropriate breed has got what it takes. Only experienced and seasoned dog trainers know how to pick a good puppy from the rest of the litter.
But even with the right breed the dog still requires conditional training, which is very difficult to pull off, and among other things. Which is why we don't suggest you even attempt to train your dog. Let dog trainers be dog trainers, in the same way let pet dogs just be pet dogs.