My puppy is aggressive, what do I do? My puppy is biting us and nothing is working to stop him! How can I get my puppy to stop biting?
I field questions like these all the time from new puppy owners, particularly new Golden Retriever puppy owners. Frequently, Golden puppies go through a phase in which they become sharkmouthed little terrors, and families are often at a loss on how to eliminate this behavior quickly and safely.
Like jumping, biting is a natural, social thing puppies do. It's an attempt to interact and play with you. Puppies explore the world with their mouths, so when they nip at your hands or clothes, that's an attempt to explore you and engage in a social interaction. Sometimes, a worked up puppy will nip pretty hard and vocalize while he's doing it, which leads some new owners to worry that the puppy is aggressive or dangerous. While there are very rare cases in which puppies have neurological issues that cause unprovoked aggression, the vast majority of concerned owners simply have a puppy who gets overstimulated and mouthy.
I approach this behavior just like I do with jumping, and if you read both articles, you see the consistency in the philosophy between that one and this one. The key to getting rid of an undesired behavior like biting is understanding what motivates it, removing the reward for it, and rewarding an alternative behavior.
Understand the Motivation for the Behavior
With biting, the motivations are fairly straightforward: dogs mouth at each other while playing, and dogs explore the world with their mouths. So most mouthing isn't aggressive, and it certainly isn't related to dominance in most situations. Rather, it's an attempt to take out the urge to mouth things, and it's an attempt to initiate play with you. Getting your dog to stop doing it means understanding that so you can make sure that it doesn't get him the rewards he's seeking.
Remove the Reward for the Unwanted Behavior
The reward for biting is your attention. That means that loud noises, sudden motion, eye contact and continued interaction can all reinforce the biting. So if you're having problems with a nippy puppy, be sure you're not accidentally rewarding him by paying him more attention when he bites. A firm "no" is often recommended to stop a puppy from biting, but in my experience, it can actually be a reward since it can be mistaken for play or at least attention. So can pushing the dog away from you. Many, many dogs find a push highly reinforcing, even if you intend it as punishment. Jerking your hand away is also potentially a reward or potentially an accidental signal that you want to play.
Some trainers recommend a high pitched yelp when your puppy bites you, and I've seen that work well, since it's something that dogs sometimes do with each other to signal that a bite was unwelcome. However, humans aren't always great at speaking dog, and some pups simply misinterpret a yelp as a play noise and take it as a reward. If you yelp and your puppy gets even more energized, the yelp probably won't help.
One thing that works well to remove the reward is to freeze, become completely silent, and look up and away. The puppy is trying to get more interaction, so if you remove all interaction and energy at the moment that teeth touch skin, you can show him that biting is having the opposite effect from what he intended. He wants to play a prosocial game and interact with you; you're showing him that biting humans turns them into boring statues. Just like with other methods that use ignoring, the idea here is not just to ignore what you don't like but rather to remove the reward of your attention.
Again, like with jumping, you will typically see extinction bursts when a behavior is about to improve. The puppy may try biting harder or more excitedly for a brief period once he realizes that biting isn't getting him what he wants. That is a sign that your technique is working, and giving up during the extinction burst will simply teach the puppy that he's right to try biting harder. An extinction burst is a sign that you're about to be successful, so stick with it.
However, as with jumping, sometimes dogs are too forceful or intense for us to play statue long enough to teach them that it doesn't work. Most puppies who interacted with their litters up through eight weeks have learned enough bite inhibition that they don't bite intensely and break the skin, since their littermates have taught them how to bite softly, but you may not be able to ignore the biting of a puppy who was removed earlier or a puppy who is simply more intense than average. In these cases, you may need to non-reward your puppy by removing yourself entirely from the situation by, for example, standing up or stepping over a baby gate.
Reward an Alternative Behavior
You can often speed up the reduction in an unwanted behavior by teaching and rewarding a behavior that's acceptable to you and is incompatible with the unacceptable behavior. With biting, that means helping your dog learn how to interact appropriately while still taking out his urge to mouth and play.
Be sure that you have an appropriate toy at hand when you are playing with your dog. If he bites, you freeze and play statue. Once he stops mouthing for even a moment, waggle the toy. Praise him and play with him if he puts his mouth on the toy instead of you. If your timing is good, your puppy should learn that biting at toys gets him good things, but biting at skin or clothes takes away good things.
Another alternative behavior is licking. You can teach your dog to give you a kiss instead of a bite. In my family, licking is considered gross, so we tend not to teach this particular behavior, but many people like it when their dog gives them a nice kiss on the hand, so you can teach your nippy puppy to kiss instead of biting by praising him when he licks. You can even put a dab of peanut butter on your finger and only let your puppy at it when he is licking rather than biting that finger. Then you can say "kiss" when he is reliably licking instead of biting. That can give you a command for your nippy puppy that you can use rather than purely ignoring him. You can teach him that kissing leads to more positive interactions, including peanut butter, and that biting pauses or ends positive interactions.
Most professional trainers have only seen one or two truly aggressive puppies in their lifetimes, and I've personally never seen one. I have, however, seen many puppies whose owners were concerned about aggression because the puppies were so growly and mouthy. So don't worry too much if you have a little landshark in the house. While it's possible for a puppy to be truly aggressive, it's extremely infrequent. Instead, try to make sure that your pup is not getting accidentally rewarded for the biting with attention, sound, and eye contact. Remove all potential rewards when he bites, and give him an acceptable behavior that will allow him to gain a reward.