The effect of thyro-parathyroidectomy on the blood coagulation time in the dog

Abstract

It has long been held that the parathyroid glands are in some way concerned with the metabolism of calcium in the body. In dogs killed during parathyroid tetany MacCallum and Voegtlin found a decrease in the amount of calcium contained in the blood and brain tissue, and recently MacCallum, Lambert and Vogel have shown that when blood, from which the calcium has, in large part been removed by dialysis, is perfused through an isolated limb, the nerves of this limb show extreme hyperexcitability similar to that observed in tetany. It is also believed by Wright and others that a diminution of ionic calcium in the blood leads to a prolongation of the coagulation time, and an increase to a shortening of the time. Our experiments were undertaken with the object of determining whether removal of the parathyroids (and thyroids) in the dog will produce any effect on the speed with which the blood coagulates, and so presumably, point to a change in its calcium content. We adopted the graphic method of Cannon and Mendenhall of estimating the coagulation time, with one or two slight modifications, and found it to work satisfactorily. The dog was anesthetized with ether, the left saphenous artery clamped close to the femoral from which it arises, ligatured on the distal side and then opened between the clamp and the ligature, The coagulation tube or canula was made so that it fitted tightly into the central end of the incision, and on relaxing the clamp a sample of circulating blood was obtained. The canula was then plugged with plasticine, quickly removed to a waterbath kept at a constant temperature of 25° C. and the time recorded. After each sample of blood had been secured the artery was thoroughly washed out with Ringer's solution.