Gina tries to chew on just about anything she can, she is 4 1/2 months old now. She has plenty of toys, and rawhide chewies, that I give her anytime she tries to eat my fingers. For the snapping and growling, I would recommend a training class for you both. I don't know how you feel about PetSmart, but they have a great puppy class, that Gina has gone through, it was well worth the time and cost of the class. Hope everything turns out alright for you.
Cheers Quad
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RIP Megan 3/1998-5/28/2013