Any dog can bite, but large dogs can inflict more harm.
When a dog bites its owner, the issue isn't a dog problem, but an owner problem. In most cases, dogs bite their owners because they don't respect the hand that feeds them--they feel entitled to enforce their rules because their owners have not properly trained them. In many cases, the owner has missed many warning signs from the dog before the bite. Other causes include abuse, frustration and fear.
Any dog can bite--but some dogs, simply because of their size and strength, can inflict more damage. People who want a dog for intimidation often choose larger dogs typically developed as guardians, such as German shepherds, Rottweilers and chow chows, or dogs with a reputation for biting, such as pit bulls. These dogs typically require a lot of training and exercise in order to become canine good citizens. If they aren't trained and don't respect their owner, they will challenge authority and move up in the pack hierarchy--and they may feel entitled to bite if challenged.
Dog aggression is a very complex topic, but in the dog's mind, its reasons for biting may be quite simple. If it bites when its resources--food, its position on the furniture or a toy--are threatened, it feels entitled to "punish" the owner for encroaching on its territory. Dogs that spend most of their time chained and isolated become very frustrated. Dogs are active, social animals and chaining a high-energy working dog creates such built-up frustration that it's more likely to bite the owner, children or passers by. Habitually abused dogs, dogs that suffer chronic pain, or that are unsocialized and anxious may bite out of pain and fear.
Most dogs give ample warning before they bite, but many owners don't understand what the dog is telling them. Dogs communicate by body language, often subtle and easily missed if you don't understand what the dog is "saying." A wagging tail may mean the dog is relaxed or friendly--or that the dog is warning you that it's ready to bite. Sherry Woodard, writing for the Best Friends Animal Society, cautions that some dogs give only a brief warning before they bite.
Puppies learn bite inhibition--inhibiting the force of their bite--from their mother, littermates and through early training and socializing by their owners, according to the Partnership for Animal Welfare. A dog with good bite inhibition doesn't bite too hard when playing, fighting or when warning another dog or person to stay away. A dog that has never learned bite inhibition is more likely to bite instead of give a warning snap.
Fair, consistent training and rules are the best way to prevent your dog from biting you for any reason. Puppies are cute, but as they mature into adolescents, they may start to challenge their owner's authority if the owner hasn't laid the first building blocks of training early. At the first sign of growling, guarding or threatening, get professional help from a good dog trainer. Deb McKean's Nothing in Life is Free, or NILIF, program is designed to be implemented into daily living, and merely involves requiring the dog to "work" by executing a basic command before every reward, meal, treat or walk. See the Resource section for more detail