Abstract
In dogs given hypercalcemia through overdoses of vitamin D (Vigan-tol), parathormone (Collip) produces a short initial rise in serum Ca followed by a lasting fall. About 12 hrs. after the beginning of the fall, a compensatory rise be-gins. It may exceed the initial Ca figure. If the hyper-calcemia is moderate the serum Ca fall is of value, but if extreme, the result may be fatal.