If your dog bites you every time you take anything away from him or give him a command or, even worse, when you caress him, then you have a real problem. So many owners let this habit grow until the dog is master of the situation! It is over-sentimental owners who produce biting dogs, and few of them on their own, even with instruction, can cure this vice. They need expert help, for the cure is to return violence with violence.
If you are going to cure him yourself, suspend him off his front legs by his choke chain as he is about to bite, and scold him in a violent tone of voice; do not put him back on his front legs until he shows signs of discomfort (usually after 10 seconds.) Now he will be subdued; caress and praise him. Repeat this process every time he persists in the habit; you will certainly have to do so several times if the vice is deeply ingrained. A dog despises you if he bites you; force him to respect you. It may sound cruel, but it is not, and it is much kinder than death in the gas chamber, to which further biting may well lead. Until he is really cured, make sure he gets no opportunities to attack visitors and, in any case, take out an insurance policy so that you will not be out of pocket if he should bite someone.
Some breeds, especially German Shepherds and Corgis, will attack anyone who approaches their owners, yet are perfectly sweet when their owners are not around. It is part of their herding instinct and, if not checked young, is quite incurable. The owners enjoy it at first instead of severely scolding their dogs, and by the time the dog is about 18 months old, it is difficult to stop. Taking the dog, muzzled if necessary, among crowds is one of the best way to cure this habit. Get people to touch him (muzzled), and give him a terrific scolding if he attempts to attack. If this fails, get someone who trains dogs to snatch him from youy and really shake him when he shows signs of being vicious. He must be defeated, then praised.