Adult Lab and Lab Puppy - Showing Teeth

Question
Hi there,
We have a 4 year old female lab named Godiva. She is the sweetest dog. We recently adopted a female lab puppy named Casey, she is now 3.5 months old.  Whenever the dogs are together, I dont know if they are playing or fighting but I think they're fighting. The puppy is in her biting phase and nips Godiva's face, mouth, ears, etc. and Godiva tries to put her in her place by knocking her over, pushing her away, mouthing her throat/neck, etc. The puppy doesnt like this and shows her teeth and snaps back at Godiva. Soon, both dogs are showing their teeth and mouthing/nipping/biting each other. We separate them but the puppy doesn't seem to learn and keeps going back for more.  I dont want my dogs to become aggressive. They are only good around each other if we are giving out treats. Then, they are two angels sitting next to each other. I've never seen Godiva act this way around any other dog. She has never shown her teeth before we got Casey. Should I be concerned?  

Answer
Hello this is best answered with links: http://www.dogbreedinfo.com/topdog.htm


this one tells about domance and pack rank among dogs,

this one tells about if you should get two dogs: http://www.dogbreedinfo.com/articles/seconddog.htm

and this is a page of pictures of all kinds of dogs just playing: http://www.dogbreedinfo.com/play/play.htm


Real growling is unmistakable I tell anyone who asks if there dogs are palying or fighting...real growling is full blown bared teeth snarling and ready to grab the other dog into a bad fight....play growling in puppies is mumbley grumbles with some light growling and normaly they yip or bark while in play also...an older dog and paticularly labradors are prone to grubmling and mumbling during play my own labrador will put my jack russell terriers whole snout in her mouth then he will snap at her she will start nibbling his neck he will chew on her flabby cheeks and they are just playing...check the links above you will find useful material in them. also genrally if the dogs are really really growling one would genrally have gotten bitten already.