Puppies are a lot like human children. They spend much of their time exploring, playing and investigating their surroundings. The difference is puppies use their teeth to investigate by nibbling on human hands, arms or clothing. This is normal for puppies, but discourage it as dogs get older.
Puppies grow their first sets of teeth in their first few weeks. As it is for children, cutting teeth is uncomfortable for puppies. This leads puppies to chew on everything from shoes to hands to help them relieve some of the discomfort. Teething usually lasts from four to six months and is normal, but if the chewing behavior -- known as mouthing -- is not curbed by 6 months of age it could spell trouble.
Dogs enter adolescence at about 6 months, and like any budding teenager, can be difficult to handle if they have not been raised properly. And while light puppy nips on your hands might seem cute, an adolescent dog's jaws and teeth are much more powerful. Mouthing can become a way for your puppy to try to control you and assume the alpha position in your home as he grows into a strong adult.
Play and Bite Inhibition
Puppies bite everything they can get their mouths around, including each other. When a pack of puppies play there is much wrestling and biting, which often comes to a brief end when one puppy bites another too hard. When a bitten puppy yelps, it startles the biter, teaching him to control the strength of his biting and mouthing. This is called bite inhibition. This startle reaction is a key to ending mouthing before it gets out of hand.
Curbing the Behavior
When you play with your dog, let him mouth on your hands. Wait until he bites hard, then yelp as if you’re hurt and let your hand go limp. This should startle him enough to get him to stop mouthing you. Playing with your dog, especially when she's young, is a vital step toward socializing her and teaching her proper behavior around people. Also, giving her appropriate toys to chew can help steer her away from your hands, or other bite-sized items in your home.