lab puppy bites hard

Question
Dear Labman,
I have a 7-week-old female lab who often bites me very hard.  I don't mind the nibbling and gentle bites, but she is drawing blood and causing bruises, not to mention pain!  I have tried telling her "no" and "bad girl," and I now smack her nose when she bites hard.  I don't want to keep doing that, since they respond better to positive rewards.  When she bites hard and I correct her, she gets really mad and comes back at me worse.  I now put her in the playpen when she does this, hoping she sees when she bites that I will walk away.  I don't want her to keep up with a bad habit.
I have even tried blowing on her head when she chomps down.
Please help!!  Thank you for your valuable input.
-Donna

Answer
Young Labs, which I know best, and other puppies tend to very bad about biting. You see a litter of them, and all the ones that are awake are biting another one or themselves. I am not even sure they realize that when they are alone, if they quit biting, they would quit being bitten. At 3 to 4 months they are getting their adult teeth, and it seems they spend every waking moment biting or chewing. One thing you can do at that stage is to knot and wet a piece of cloth. Then freeze it. The cooling will soothe the gums. Only let the puppy have it when you are there to watch it. I maintain a Lab's favorite chew toy is another Lab. Otherwise they settle for any person they can. They keep hoping to find one that won't yelp, jerk their hand away, and leave.

You just have to keep on correcting them, hundreds of times, not dozens. Provide sturdy, safe toys such as Kongs and Nylabones. Avoid things they can chew pieces off and choke on them. Keep them away from electrical cords. Crates are essential for most young Labs and other dogs.

The pet stores are full of toys that many dogs will quickly chew up into pieces they could choke on or cause intestinal blockages. If you are not there to watch, stick to sturdy stuff such as Nylabones and Kongs. Keep a close eye on chew toys and quickly discard anything that is coming apart in pieces. Rawhide is especially bad because it swells after being swallowed. I don't trust any of the consumable chews. The dogs just gnaw them down to a dangerous size too quickly. These problems are the worst with, but not limited to, large, aggressive chewers such as Labs.