My GSD is 15 weeks. Last two days I think her bite has weakened and when the rag comes out of her mouth she licks
her lips. She licks her lips in a funny way. Maybe she is tating blood? Could this be the start of her teething?
Time to stop playing tug? I was thinking 15weeks is to early but now I think once again I am wrong.
Thanks, STeve

Depends on the pup, if there's any question, stop playing tug till the last tooth comes out. Some dogs continue playing tug during teething, some dogs don't. If you see a negative reaction to tug during teething them stop the tug. 15 weeks is old enough for teething.

My GSD is 16 weeks, and last week we noticed blood on her favorite toy after tug. She also licks her lips after tug, but is as into the game as ever. She does chew her raw hide chewy bone in the middle using only her front teeth. where before she would try to tear the end with the side of her mouth.
I think it is the start of teething.

I'd say don't push the pup into biting or tugging, he'll do what's right for him.

He needs to keep chewing, it's part of the whole teething process. Forcing him to bite more/harder than he would naturally do on his own "can," have negative consequences.

Make some teething chews for him. Take a durable cotton material, (I used the leg of a pair of jeans I was cutting off anyway) cut it into rectangles, and roll the fabric up to make cigars sized chew toys. The size of your pups mouth will be a good guide. If they're too big he'll have trouble using them on his molars, too small and they won't last.

Soak the cloth in clean water then roll the rectangles up till each one is about the size of a cigar. They should be very wet, but not sopping wet (after the first day you'll know how wet wet is) and put them in the freezer. They're small enough to freeze in a couple of hours so you can rotate them as the day goes on. Keep giving him the frozen cloth cigars to chew on, encourage him to gnaw on them. They last fifteen to twenty minutes before they're thawed. When one's thawed put it back in the freezer and give him another. Let him chew on them as much as he wants to and make sure they are very cold/frozen.

The cold numbs his gums and the chewing action speeds up the teething process. When you crate him for the night take the cigars and wash them in clean hot running water because dog slobber doesn't freeze as well as tap water and they'll be nasty by nightfall.

And for the Moms reading this, yes, it's just like teething children.