The influence of experimental cretinism upon nitrogenous metabolism in the sheep

Abstract

The object of the investigation was to determine whether athyroidism in sheep is associated with any striking abnormality of intermediary metabolism, such as might be revealed by the nitrogen partition of the urine. The subjects were three sheep which have already been described before this Society by Simpson. At the age of two months they had suffered the loss of the thyroid and internal parathyroid glands, and had subsequently developed into typical cretins. One year after the first operation the external parathyroids also had been removed. While the later condition was of course not that of uncomplicated athyroidism, symptoms referable to the loss of the parathyroids were but slightly marked. Tetany, in particular, was never observed. When the animals came under my care they were one and a half to two years old. To furnish a basis of comparison two normal sheep, nearly four years of age, were included in the investigation. As the most convenient way of avoiding the difficulties caused by variable appetite, etc., all five animals were starved. The urine was collected as voided. The normal animals endured fasts of five days'duration with little apparent distress or enfeeblement. Of the others two rapidly weakened, and succumbed within six days; the third was in excellent condition after seven days without food. Below is shown the ascertained distribution of nitrogen in the urine of one normal and one operated animal. The records of the others were of corresponding character. Nitrogen partition in the urine of the normal sheep is seen to follow the general mammalian type, the only point worthy of special note being the comparatively small proportion of purine nitrogen excreted as allantoin. In the urine of the thyroidectomized animal the only constituents apparently affected are ammonia and creatine.