Normal puppy behavior?

Question
I have an 8 week old orange sable Pom puppy. My question is this, how do you determine normal puppy biting, growling play behavior from poorly bred aggressive behavior? My puppy is very bouncy and playful but is always snapping at our hands when we try to pet her and attacking our pants legs when we try to walk. She is hard to hold also and always wants down so she can play some more. She has stopped biting at our faces as much and looks very confused when we "yelp" at her but a minute later she is back at the jumping and attacking our hands. She is very good at sharing her toys and is not protective of any of them or her food. In fact she likes to get a toy and climb in our laps to chew on them and gives them to us and then takes them back pretty gently. I thought we had a good read on the breeder and the parents were both very sweet but maybe we misread her? She was the lone female pup out of a litter of five. She is very curious and so far only afraid of the garbage truck. She even chased the vacuum cleaner while I ran it! She is very friendly and calm when I take her out to meet other people and children and very friendly to my friend's 5 month old Yorkie. But! The biting and growling while she is playing is worrying us that maybe she is not well bred. Is she normal or do we have trouble on our hands? She also does not take to roll-over or scruff shake very well, makes her worse!

Answer
All of this is perfectly normal for her age and it is a great time to start nipping this behaviour in the bud so that it does not progress into bad adult behavior.  She is playing with you but she is also trying to assert her dominance over you.  In a litter of 5 she would have had to be in a pecking order-now that there is no one to fight with-she is "queen bee".  Although you say she does not like to be rolled on her back-do it several times a day and hold her there till she is still.  This is a dominance pose over her.  It is asserting that you are the alpha-not her.  I would not suggest roughing her up-it is fun but that is what dogs do when they are being aggressive too-it may send mixed signals while training her.  When she bites, hold her muzzle closed and tell her "no bite" in a firm tone.  You can also try to stick the part of your hand she is biting farther in her mouth that is comfortable for her for a few seconds.  If it is unpleasant, she may stop doing it.  
You also have to remember that she is JUST a baby at this age and will take LOTS of patience and consistancy.

Best of luck!

-Trish
Gemini Poms
www.geminipoms.com