two children with mother dog

One day in the morning, I hear children's voice which wake me up.  I look at them.  The picture make me worrying.  Two 2- yrs girls are playing with mother dog and six baby dogs.  One girl takes a puppy out of the mother's breast and then the girl comes to suck at the mother dog breast.  I am so surprise that the mother dog doesn't do anything bad to that girl.  Who can carrify this situation for me?