Because it misses its puppies, have another litter and let her keep one of the puppies so she can love it :) and plus she hasnt been outside very much, so her claws could be quite sharp and uncomfertable, if in any doubt go to your vet!
they are puppies, dog gone it!
Yes it will if it is really protective over her puppies!
Usually because your dog is teething.
Vet. Immediately.
She probably isn't biting them. It is more like she is nipping them. This is normal. This usually occurs as a sign of discipline when the puppies are being rough. The mother dog will tolerate the puppies, but she will control her young when they nurse to hard.
A shrew's bite or scratch might make a dog think "ow" but not a lot beyond that.
to the leg its just small scratch
no you dont not unless you get the mother in another room or if the mother is calm the dog will bite you if you touch its puppies.
because the big dog has a bigger mouth and the smaller dog has a smaller mouth.
Depends. Is it a stray or a strange dog you have never seen before? Then yes just to be safe.
Ah I have no clue that's why I asked you
He/she's probably just trying to get you to play. Or he/she is trying to be dominant; it all depends on the dog's body language.