I have experience this with one of my mini pins when I was breeding them. It is very scary...
I had to give her additional injections and to supplemental feedings for 12 hours as her little body caught up from the demand from the puppies (she had four) I am a firm believer of calcuim supplements 1 week before delivery and while they are nursing. I know there is a lot of controversy on this subject, but this practice works for me and my girls and will continue doing it....
