mean puppy!

Question
I just adopted a black lab mix puppy from the SPCA when he was 8 weeks old. He is now 12 weeks old. The last week or so he has gotten really aggresive, biting me hard and growling at me. I don't know where this is coming from, he used to be a sweet puppy! The only thing I can think of is for a few days my husband was smacking his snout when he would bite him, after receiving some bad advice from a cow-worker. I am hoping this hasn't made the biting worse. What do we do?

Answer
Hello Krissy, I think he is just coming into his own.  Getting more comfortable and trying out new things.  Using a firm NO when he bites will help, also remember to give him something else to chew on.  Just like a small child, tell him no to unacceptable behavior and lead him in the right direction for good behavior.  He is still sweet and just like babies sleep all the time, however,  toddlers are very active.  When he gets to 4 months join a dog dog obedience class.  Thanks for asking, Cindy Lou :)