Abstract
With regard to the question as to whether the thryoid and parathyroid glands become less and less essential to the organism as age advances there is some difference of opinion. Vincent and Jolly 1 found that in the various species of animals which they used (cats, dogs, foxes, monkeys, rats, guinea-pigs, rabbits), the symptoms following thyroidectomy and parathyroidectomy were not influenced, to any extent, by age or sex. In the case of dogs the writer can corroborate this statement, but it appears to be otherwise in the sheep, as the following account of experiments on this animal will show.
In the course of another investigation 2 the thyroids were completely removed from eighteen lambs, from seven to eight months old, and twelve adult sheep, without, in the course of the six months which intervened between the operation and their slaughter, any apparent ill effects. There was no falling out of the wool, nor any of the other symptoms of myxœdema supposed to be associated with complete thyroidectomy, and several of the adults gave birth to full-time, and to all appearance, perfectly normal lambs.
From three of these lambs, at the age of two months, the thyroidswere renoved, the two external parathyroids being left behind, and from two others at the same age (also born of thyroidectomized mothers) all the thyroid and parathyroid tissue was taken away. The latter, in the course of ten and nineteen days respectively, developed typical and acute parathyroid tetany. In one, the first fit was fatal in less than an hour from the onset, the rectal temperature being 112° F. one minute after death, and in the other, which was killed during the fit, the thermometer reached 108.7° F. immediately before death.
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