Hypothyroidism in the Sheep

Abstract

The effect of the oral administration of methyl thiouracil at three dose rates to pregnant ewes has been studied. Observations were made on foetal skeletal growth and maturity, foetal and maternal thyroid iodine, plasma-protein-bound iodine (PBI), cholesterol, phospholipid, total esterified fatty acids, and calcium. A retardation of osseous growth and a significantly greater retardation of osseous maturity was found. The thyroid iodine concentration in both ewes and foetuses and the maternal total thyroid iodine in all treated groups were decreased but the foetal total thyroid iodine was reduced only in the two highest dose rates. Significant reduction in the foetal FBI was found only with the two highest dose rates and no significant changes were found in the maternal FBI concentration. Increases in all lipid fractions and a decrease in calcium concentration were found in the foetal plasma in the treated groups.