Why dogs become protective of there owners?

Dogs who clearly know that the owner is the leader will likely live their lives in comfort and happiness. These dogs know that the owner will protect them from harm and ensure their well being. These dogs will trust their owner and respect him, looking up to him for guidance and directions. If the owner however is weak, the dog will take over the leader role and may feel compelled to defend its owner.
It may start one day and the owner may think it is funny, or even reward it. A stranger comes near the owner to talk, and the dog will growl. The stranger will stop in his tracks and leave. The owner therefore pets the dog reassuring him: ''Buster, it's OK, that's my friend.'' By petting the dog at this crucial moment the dog feels that the behavior is approved and will resort to the same behavior next time.

So a week later, another stranger approaches the owner and Buster starts growling. This stranger this time is not intimidated by the growl and will therefore continue getting close. Buster therefore becomes more aggressive to send him away. He growls lifting his teeth and showing his pearly whites. The stranger goes away. Buster now has learned that he must act more aggressively now to send away strangers, and a new behavior has been learned. This shortly becomes a bad habit and the owner has given up and decided that it is just a ''trait''.
Some owners actually tell others with pride ''my dog is very protective of me''. They feel that because their dog protects them, they must love them so much that they would what it takes to protect them. They however are missing something crucial: their dog is unbalanced and unpredictable, as he will react when no threat is present. A balanced dog would protect its owner if there is reason to do so, such as when the owner is being attacked by a robber or simply somebody with malicious intent.

Many times protective dogs are dogs that have no limitations in their lives. These dogs are allowed to sleep on beds, block doorways, lean on their owners for attention and beg for food. There are no rules to show them who is the actual leader. Therefore they become more and more dominant and resort to protective behaviors because it makes them feel powerful, just as the alpha pair leaders feels when it protects their family /pack.
Some dog breeds have a higher chance of acting protectively. Protection dogs, breeds that have been used for centuries to guard are more likely to be protective of their homes and owners. These breeds need to be socialized from an early age and must learn to accept strangers in their property. Allowing them to be over protective may make them be a big liability.

Many times dogs may become protective of children. This is because they can sense their weakness and vulnerability. While this trait is not really a defect, it becomes so, if the dog becomes protective when not necessary. These dogs may resort to growling and biting even when people with good intentions come too close. At times, dogs become protective when owners are sick or frail.
Some owners of female dogs at times notice that they become more clingy and protective when pregnant.They may be more protective of their owner and toys. In some cases, instead dogs may become more protective when they somehow sense their owner is pregnant. These dogs will stick near their pregnant owner and even block people from coming too close.

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