Abstract
Though it is a well-known fact that tetany does not often follow parathyroidectomy in herbivorous animals, no adequate explanation has been offered. Of the 2 interpretations offered, the more common is that the decomposition products of the food of herbivorous animals are less toxic than those of the food of carnivorous animals. The other is that aberrant parathyroids are sometimes found in the thymus gland of herbivorous animals. Parathyroid tetany in the goat following the removal of the thyroid and the parathyroids has not occurred as frequently as in the dog. MacCallum et al 1 who operated on 8 goats, noted violent tetany in only 2 cases. Christens 2 observed tetany in 3 goats following thyro-parathyroidectomy.
A series of 12 goats were thyro-parathyroidectomized by removing the entire thyroid capsule with the contained thyroid and parathyroids. The blood vessels were ligated at least one inch from the thyroid capsule so that any parathyroids which might be close to the superior pole would be removed. The part of the thymus lying outside of the thoracic cavity was also removed in all but 2 of the animals. Half of the animals were young; the other half, young adults. Two of the former were less than 2 months old when the operation was performed.
The animals were kept on a diet of corn, oats, hay and water. All were autopsied and a careful search was made for any accessory parathyroid tissue. Blood for the blood calcium determinations was drawn from the external jugular vein. The determinations were made according to the method of Clark and Collip. 3
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