Not to scare you but I have read a few studies linking kidney stones as indicators of liver shunts.
Often, some dogs dont show any typical signs other than kidney stones.
Canine Liver Shunt
Has your girl had a BAT performed on her prior to breeding? I would definitely talk to your vet about this option before you do a C-section because sometimes the anesthesia is more than they can process.
Crossing my fingers and wishing for the best for you and your girl.