Parturient Paresis. VIII. Results of Parathyroidectomy of Cows

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Abstract
Nonlactating pregnant cows and nonpregnant lactating dairy cows were thyroparathyroidectomized. Blood serum Ca and plasma inorganic P analyses were made at various intervals before and after thyroparathyroidectomy. A marked decrease in serum Ca and less decrease in inorganic P occurred after removal of the parathyroid glands. None of the cows exhibited symptoms of milk fever, although the serum Ca of several of the cows decreased to the range where milk fever symptoms occur. The natural diet of ruminants has a high Ca:P ratio and, on this diet, the adult ruminant cow can maintain pregnancy, parturiate, and lactate in the absence of parathyroids.