Do get to a positive reward based training class asap. Good ones usually do a home visit before the puppy class.
DO not follow any advice re squirting water, yelping or pinching the puppy (unless you want more further problem behaviors as well)
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Below is excellent advice by Sally from the above page
Biting is a normal puppy behaviour. Puppies investigate the world through their mouths. If it is within reach, it will probably be picked up and chewed! If it is exciting and moves fast it will definitely get bitten. Dogs play by using their mouths because they don’t have hands.
Puppies need to bite and they need to play. What he/she is doing is simply trying to elicit play. Play is by far the best way to bond with your pup and is a great way to reward him during training.
Use tug toys that he can bite. Old knotted towels or a favourite toy with string attached. Unwanted dressing gown cords are ideal. You need to encourage him to bite one end of the toy whilst you hold the other end. Then you can have a great game together without getting bitten.
Ensure your tug toys are long enough and soft enough for your puppy to happily bite. Your toy should touch the floor whilst you are holding the other end. This allows you to animate the toy and keep the game low to the ground and not encourage jumping up. It also puts distance between teeth and hands.
Keep these interactive toys out of your pups reach whilst they are not being played with. It will keep them more novel which means the pup is more likely to want to bite and play with them when given the opportunity. Plant toys around the house and garden (out of puppies reach) so you have them easily accessible and as much as possible, take the game outside.
Rotate chew items that you leave on the floor to also keep them interesting.
Do not play with your puppy unless you have a toy for him to grab. Don't let anyone in the house roughhouse with him or roll about on the floor with him.
Start by animating the toy on the floor and saying 'getit' every time your pup grabs the toy. You hold on to the toy and let him grab it and shake it. Let go of the toy sometimes so that puppy is encouraged to come back to you to get you to start the game again.
Also teach a word for letting go. To do this you simply stop the game by putting a finger in pup's collar and keeping hold of the toy, release the pressure on the toy so that it becomes boring. As soon as pup lets go say 'thank you' and immediately invite him to grab it again with a 'getit'. He will quickly learn to let go when you stop playing in order for the game to start again and eventually the word 'thankyou' (or your word of choice) will become his cue to let go.
Once your pup is getting the idea of the game then you can start to add in a 'sit' 'are you ready' before the 'getit' and before you know it you have a dog sitting and waiting patiently for the game to start.