It can be comforting as an owner to know that it is VERY normal for puppies to have very horrible biting and nipping habits. The problem is three fold - not only
that they are:
Energetic and looking for play and attention, but
They also uses their mouths to explore the world (and this can sometimes look like biting down hard on things to see what it's like, texture, etc...), and
Burn off teething frustration.
Generally, excessive biting towards humans, even hard biting, as a puppy is not an indicator of future aggressive behaviour as an adult dog. Although the biting is happening for a variety of reasons, and understanding why it happens is helpful context, it really doesn't matter which specific reason it is happening at any given moment. What is most important is that they find something reinforcing about it - so the more often it is repeated the more likely they will continue to do it again because they find it so reinforcing.
Many puppies also display this behaviour due to general frustration, boredom, or overarousal. Add more enrichment strategies and ensure your puppy is getting at least 18 hours of sleep per day to ensure they are getting their needs met.
For those moments where biting persists, follow these recommended steps:
Find the least dramatic way of stopping the reinforcement. So if the puppy is about a 4-5 on scale of 10 perhaps that's just retracting your arms and puppy may be able to stop themselves from biting. But if they are a total nightmare 10/10 then you have to calmly separate yourself. Place yourself behind a baby gate (or use a door just opened a crack so you can keep an eye on them) for separation - every single time. Wait puppy out until they give up and walk over to find a toy or entertain themselves some other way. Make sure you do this calmly and not running, because they will likely find running reinforcing/activate a chase response. Simply make your way over and squeeze yourself behind a gate (or door). Puppy may try some demand barking or coming at you harder, thrusting at the gate. Ignore. Your separation only needs to be about 60 seconds for the message to be received.
Stay consistent with the above - every single time teeth touch skin, separate yourself. It is not ideal if you have to put your hands on the dog, which is attention that they may still find reinforcing. It's the separating yourself from them that teaches "my playmate goes away if I bite."
I often hear from clients - "we've tried this, and it's not working." Stay consistent. Period. If you've got a "stubborn biter" he may take longer for you to see a dramatic decrease in this behaviour. Try not to feel upset or discouraged - remember that it's an instinctual behaviour and he can't help it.
If they bite again when you return - you guessed it. Separate yourself again.
One important note is to allow gentle mouthing (that's the 0-3 from the 10 scale that we mentioned above) to teach puppy what is acceptable and to have a soft mouth. Learn more at this video on Bite Inhibition Training.
• From Fearful to Fear Free, by Dr. Marty Becker, Dr. Wailani Sung, Dr. Lisa Radosta, Mikkel Becker
• Don’t Shoot the Dog! The New Art of Teaching and Training by Karen Pryor
• The Culture Clash by Jean Donaldson
• Before and After Getting your Puppy by Ian Dunbar