Calcium in the Diet
Excessive calcium in the diet will actually interfere with the absorption of zinc and manganese from food, and both of these minerals are essential for healthy puppy development in the womb.
It may also predispose the mother to difficulties during labor (dystocia), and has been incriminated in predisposing the pups to developing bloat (gastric dilatation) after birth.
Excessive calcium may even increase the risks of milk fever (eclampsia) - a serious, potentially fatal form of calcium deficiency in lactating mothers