The Effect of Single Doses of Thyroid Gland on Fowls

In a former article* were published the results of three years of observation on the effects of feeding fowls thyroid gland. The usual symptoms of hyperthyroidism, such as increased excitability, polydipsia, polyphagia, tremors and diarrhea, were recorded. Four peculiar phenomena hitherto unnoticed were described: (1) Premature “experimental” moulting; (2) Replacement of the former colored feathers by depigmented white feathers; (3) From prolonged toxic dosing neuropathological symptoms marked by depression alternating with flashes of excitability, followed by cessation of co-ordinated movements; (4) From further administrations of large doses, death preceded by characteristic tremors. In all these experiments daily, systematic administration of thyroid or preparations of the gland were employed. This method required much time and trouble, and at the periods of acute poisoning the fowls had to be fed artificially twice a day. Attempts at simplification were therefore made.