Dogs use their mouths to explore the world and to communicate, but your pup needs to learn when to keep his mouth -- be he barking or biting -- to himself. A 4-month-old dog is plenty old enough to teach not to bite and bark at you.
Analyze why your puppy is barking at you. Dogs bark for a reason -- they're trying to tell us something. If he doesn't need to go out and it's not time for puppy supper, at 4 months old he may be starting to explore where he fits into the pecking order. Now is the time to assert yourself as not just mom but as leader of the pack. Declare a moratorium on dominance-heavy games that have a winner and a loser, such as tug-of-war, and substitute simple training exercises such as come, sit and stay.
Select a sound that you can make to let your puppy know that what he is doing is unacceptable. If a puppy plays too rough with his mother, she growls. If he chomps on a littermate, a shrill "yip!" results. For you, a sharp "Ow!" will do, but whatever sound you choose, use the same sound anytime your puppy does something you disagree with; TV's Dog Whisperer, Cesar Millan, uses a trademark hiss that he says his grandmother used on him.
Isolate your puppy immediately when he bites. Make your noise to let him know he's done wrong, then put him down, turn away or put him back in the playpen. Withdraw yourself, either your attention or your actual presence. The objective is to show him that when he bites, the fun's over. Don't put him in his kennel -- you want that to be a good place, a place he doesn't mind being, so don't associate it with rejection or punishment. Wait a few minutes, then go back and play again. Repeat this any time he bites until he gets the idea. All his pack (human family and friends) need to do this consistently.
Ignore the barking until he stops to take a breath. Instantly say, "Quiet," and give him an attaboy or a treat. This takes good timing and preparation (having a treat handy). It would be a good time to use a clicker if you like this form of training -- the click tells him what he just did was right and a reward is coming.
Keep your own voice down and remain calm, assertive and patient. If you yell at your puppy, he may think it's a noise contest and bark louder.
- No one, not even the Pack Leader, should use physical force on a puppy. This means you don't thump him on the nose, swat him with a rolled-up newspaper or roll him over on his back. It can lead to fear biting in self-defense.