THE THYEOID GLAND AND ITS DISEASES 



229 



The- complete operation (thyro-parathyroidectomy) in four young 

 lambs (five to seven weeks old) resulted early in acute and fatal tetany*. 

 Kemoval of the two external parathyroids from the three cretins when 

 about one year old was followed by only slight symptoms. According to 

 Simpson age is an important factor with regard to the effects of both 

 thyroidectomy and parathyroidectomy. The "typical cretins" of Simpson 

 are described as "small and stunted, with broad faces and rickety limbs. 

 The wool was coarse, but did not tend to fall out." In some of the young 

 animals (cats and dogs) operated on by Vincent and Jolly interference 

 with growth was very striking 

 but the other "cretinoid" symp- 

 toms were absent. 



Basinger in 1916 carried 

 out an extensive research on 

 thyroidectomy in rabbits. Out 

 of 140 animals operated upon 

 "typical cretinism" was pro- 

 duced in 86. The experiments 

 were carefully controlled as to 

 feeding, and selection of sub- 

 jects and normals from the 

 same litters. The thyroid- 

 ectomy was performed at the 

 age of 2 to 3 weeks when the 

 body weight was about 175 gms. 

 Great care was taken to remove 

 all thyroid tissue, leaving the external parathyroids intact, but it was 

 subsequently found that in a considerable proportion of cases minute bits 

 of the gland had been left behind and prevented the onset of cretinism. 

 In different litters the proportion of successful results varied from 25 to 

 90 pe>r cent. 



About two weeks after the operation the onset of cretinism was detect- 

 able. The hair became dryer than normal, did not lie smoothly and could 

 easily be pulled out. Retardation of growth was noticeable as early as 

 the third week ; it was greatest from the eighth to the twelfth weeks. By 

 the end of the tenth week the average weight of the cretins was 750 gms., 

 while that of the controls was 1400 gms. The posture of the cretins was 

 typical. The bones were short and the muscles of the limbs too weak to 

 support the body weight. The bones showed a pseudo-rickety condition 

 (Hofmeister's "chondrodystrophia thyreopriva" ) . The skin became in- 

 creasingly dry and scaly and finally eczematous. The typical "pot belly" 

 seen in human cretins developed. If undisturbed the animals remained 

 immovable for hours. When stimulated they moved slowly and awk- 

 wardly. No evidence of the typical myxedema seen in human cases was 



Fig. %. Photograph of cretin lamb about one 

 year old, and of normal lamb of eleven months 

 (after Simpson, Quart. J. Exper. Physiol.). 



