Today a dog will lose his home and very likely, his life. He was adopted from a rescue organization by a well meaning family. When he began growling and exhibiting defensive body language the rescue group that placed him advised the new owners to "pin him down" and punish him. Not knowing any better the well meaning owners did so and were bitten badly in the face. The injury was significant enough for the owner to require medical attention including sutures. The dog will be returned to the rescue group who gave this dangerous, inappropriate and stupid advice and will likely either be euthanized or subjected to more inappropriate handling.
If this family had been put into the hands of a qualified trainer, they could have began a training program where instead of being punished for feeling uncomfortable, the dog was systematically desensitized and counter conditioned and actually taught to feel comfortable, relaxed and safe. Instead, his new family, people who he barely knew him proved themselves to be unsafe, untrustworthy and dangerous. And now, everyone loses.
It would be wildly inappropriate for me to give medical or legal advice because I am not trained or credentialed to give such advice. This is no different than non-behavior experts giving out advice. Advice that can do no harm is one thing, but advice that pushes a dog to feel the need to bite and puts people at risk is not only unethical it is just plain wrong.
When my beloved Pekingese Fooey came to live with me, fresh out of the shelter, we had an "incident" in which I was playing with a ball with him. When I went to take the ball from near him to toss it, he launched across the dog bed snarling at me guarding the toy. I got up and went and got my clicker and some treats. I started to desensitize him by shaping my taking the ball. At first I just lifted my hand and would click and treat him for no reaction. I built it up to extending my hand, then reaching it out, then touching the ball, then taking the ball and so on. Fooey never guarded anything from me every again. I am not saying it always that easy to work with a resource guarding dog, and Fooey's defensiveness could have been partly that he was not well, newly out of the shelter, didn't know me that well, etc. The point is that had I chosen to grab him, shake him and take the ball from him, what would that have taught him? Probably that I am dangerous, untrustworthy and unsafe, oh, and it would have validated his need to feel defensive.
If you have a dog that is exhibiting aggressive behavior, please do not attempt to modify this behavior on your own. Do not use methods that are confrontational, harsh or forceful, even if you have seen them done on T.V. or if your mother's neighbor's son who used to have dog one time told you to. People who are not professional, qualified, skilled or credentialed should not be recommending training techniques that put animals and people at risk. Just loving dogs, working with dogs or having lived with dogs or bred dogs does NOT make someone an expert, anymore than my having been sick makes me qualified to give medical advice.