2 THE THYROID AND 



relation of the thyroid to myx oedema was then 

 established by Gull and Ord. The highly successful 

 treatment of myxcedema and cretinism by thyroid 

 feeding was introduced by Murray, following on 

 the observation by Schiff and subsequent workers 

 that transplantation of the gland beneath the skin 

 of the thyroidectomized animal relieved the 

 symptoms. 



REMOVAL OF THYROID AND PARATHYROIDS. 



We will consider first the consequences of removal 

 of the thyroid gland in animals. The effect of 

 total removal varies greatly with the species. Thus 

 rodents are little if at all affected, sheep and cattle 

 more so ; in man and monkeys the symptoms are 

 marked, and in carnivores, especially foxes, a rapidly 

 fatal result ensues. To some extent this striking 

 diversity depends, as we shall see, on the liability to 

 simultaneous removal of the parathyroids ; for a 

 long time this was not recognized. Males are more 

 severely affected than females, and castration is 

 said to modify the symptoms. Thyroidectomized 

 animals are very susceptible to cold, and keeping 

 cats warm may save their lives ; of course thyroid 

 medication must be undertaken at the same time. 

 It is well known that human patients with myxcedema 

 feel the cold very much. The symptoms in dogs 

 and monkeys are vomiting, muscular prostration, 

 emaciation, and often death. Of great importance 

 is the frequent occurrence of tetany. The spasms 

 are at first slight, affecting the jaw muscles, then 

 they spread over the whole body and may be fatal. 



