The most upsetting thing our dog can do to destroy our trust, is bite us. Being bitten by our own dog is incredibly stressful, and of course we take it personally!
To understand why dogs bite, we first must understand the function that biting serves (stay with me, I won't get too geeky, I promise!). Dogs bite for one reason - it is effective. It provides them with whatever they were seeking, usually space, but sometimes to retain an object. Frustration biting (I'm looking at you, Tagg!) relieves tension, while puppy biting gains your attention.
If we look at biting as a behavior designed to achieve a goal, it doesn't take long to then drill down to see how we can help the dog find better solutions for achieving that goal.
For example, if your dog bites a stranger for getting too close then we need to help the dog tolerate strangers, while simultaneously teaching them a better way to communicate their desires.
A puppy seeking to gain our attention tells us that: the behavior has gained our attention in the past and thus has a reinforcement history (the puppy pushed a button and got what they wanted) and that they may need more attention OR more sleep (weird, I know, but true) or a better type of interaction from us.
Frustration biting (Tagg!) is incredibly difficult, but, we must first teach the dog that they can handle the situation, that they can tolerate frustration, and when frustration arises, there are other means of relieving tension.
Biting to retain an object or location can be extremely difficult for the humans in the house! This is a difficult form of aggression to get in front of, because we need to teach the dog to share, teach the dog that the world doesn't end if we take their thing, and we have to teach the human family members how to take things in a manner that the dog does not cause conflict.
All dogs are capable of biting. But being bitten by your own dog, or having family members threatened by your dog, is not acceptable. We can help a biting dog learn better communication skills, feel more relaxed, and become happier overall.
If a bite occurs, ask yourself: Why did my dog bite me? What was the situation? were there signs you perhaps missed? Did it come out of the blue? How do I stop my dog from biting me? Obviously this is a question best answered by a trainer, but for immediate safety, look at the questions above and take precautions to avoid them in the here and now.
Puppies bite for different reasons (usually) - the question, how do I stop my puppy biting me? Is usually a question asked not about aggressive biting, but rather play biting. Don't get me wrong, it still hurts! Those little teeth are sharp! But the answer, thankfully to puppy play biting is usually more straightforward: better play communication, higher quality of play interactions between family members and the puppy, and possibly, more sleep for pup.
A dog bite (except puppy silliness) is always serious. Do not allow it to escalate. Call a trainer and get on top of the situation before things escalate.