THE THYROID APPARATUS 39 



of the thyroid, leaving the parathyroids intact, produces derange- 

 ment of the processes of growth in young carnivoras. I became 

 convinced, from the results of my experiments, that cachexia and 

 tetany cannot have a common origin ; and I urged (1901) that, 

 in the surgical treatment of goitre, the parathyroids should in 

 all cases be left intact, and that, wherever possible, a portion 

 of the thyroid should be spared. 



My opinion was confirmed later by Jeandelize (1903), Wal- 

 baum (1903), Pineles (1904), Erdheim (1906), Pfeiffer and Meyer 

 (1907), Hagenbach (1907), Haberfeld and Schilder (1909). There 

 are observers who have adopted a different standpoint (Blum ; 

 Caro, 1903 ; Kishi, 1904), but they are very few. 



We may, then, take it as established : that the acute nervous 

 symptoms which appear after extirpation of the thyroid apparatus, 

 are genetically independent of the thyroid gland and occur only 

 where the parathyroids have also been removed; and that tetany 

 arises from the suppression of the function of the parathyroids 

 and should, rightly, be called tetania parathyropriva. Whether 

 this form of tetany is identical with that which follows the 

 extirpation of the entire thyroid apparatus is, as yet, undecided. 

 It is, however, barely possible to distinguish between the clinical 

 pictures presented by the two conditions in animals of similar 

 species and of the same age. The only apparent difference lies 

 in the intensity of the symptoms and the rapidity with which 

 they make their appearance. 



TETANIA PARATHYROPRIVA. 



The results produced by extirpation of the parathyroid 

 glands or of the entire thyroid apparatus of animals, vary some- 

 what with the species and age of the subject. In addition to 

 the typical acute tetany, which shows itself in characteristic 

 muscular convulsions, there are other acute forms which are 

 associated with symptoms of paralysis. Abortive forms are 

 occasionally seen, as well as a latent tetany, which is shown 

 only by a hypersensibility of the nerves and occurs most fre- 

 quently after partial parathyroidectomy. Finally, many animals 

 develop a chronic tetany which is associated with certain trophic 

 disturbances. 



The typical picture of an acute tetany is most frequently seen 

 in the dog and the cat, and may be described as follows : There 

 is, first, a latent period lasting 24 to 72 hours, during which time 

 appetite falls off and the animal may refuse food; thirst increases; 

 the temperature may fall and the number of red blood corpuscles 

 be diminished; and later on there may be mechanical hyper- 

 sensibility of the peripheral nerves. This is followed by fibrillary 

 contractions in certain muscles of the head, face, back and tail. 

 In the course of the next day or two the temperature rises and 



