Effect of Thyroidectomy upon Sexual Behavior of the Male Bovine

Abstract

While many workers have reported on the effects of thyroidectomy upon fertility and sexual behavior for many species, no reference has been found to the effects of such operation upon the behavior of the bull. In general it is reported that thyroidectomy is followed by involution of the sex organs with reduced fertility and sterility. 1 , 2 , 3 Berliner and Warbritton 4 found that thyroidectomized male sheep continued to produce semen but the ejaculates were smaller and the sperm abnormalities increased.

This report deals with the observations over a period of 15 months following thyroidectomy of a male Jersey, the operation being performed at the age of 4 months, and the effects of administration of desiccated thyroid, dinitrophenol, benzidine sulfate and testosterone propionate.

For approximately 60 days following thyroidectomy the animal behaved normally. After that time, however, myxedemic symptoms developed rapidly. The skin became thick and puffy; the hair became dry, brittle and sparse; body fat increased and the general appearance of premature aging is presented. One of the most striking effects is that of reduced activity. Apathy, lethargy, increased susceptibility to cold and diminished reflexes are marked.

Blood analysis, made semi-monthly, has revealed a marked lowering in hemoglobin and amino nitrogen. Values for blood fat, cholesterol, glucose and non-protein nitrogen increased. Blood phosphorus, calcium, ascorbic acid, creatine, total nitrogen, globulin and albumin were normal.

While the gonads appeared to develop normally there was complete absence of libido at sexual maturity. His reaction in this particular was tested at frequent intervals with females in estrus and in no instance could he be induced to mate.