Mil THYBOID \\l> PABATHTBOID GLANDS 759 



peculiar shaking of the foot, like thai made by a normal animal to shake 



water off its pa. Is, is a characteristic symptom. The - 1 1 «_r 1 1 1 . ■ -v t stimulation 



of tin' peripheral nerves is sufficient to induce one of tins.- attacks, which 



recur with ever increasing frequency, 1> >miu'_r at tin- same time more 



pronounced and accompanied by other disturbances, such as diarrhea, 

 profuse salivation, rapid pulse, and dyspnea (in the dog but not in I 



cat). In cases that arc not quickly fatal, the hair tends to be shed, and 

 the teeth to he improperly calcified ! in young animals). Where a certain 

 amount of parathyroid tissue has been left — for example, one of the four 

 lobes the symptoms may nol appear except under conditions of special 



strain to the animal economy, such as pregnancy Or improper <i 



Thus, in a hitch from which three of the four glands had been removed, 

 no symptoms of tetany occurred until she became pregnant. Tender the 



saint ml it ions it has been found that a diet of flesh is much more apt 



to bring about the condition than one of vegetables or milk. 



Tetany, as the above condition is called, may also become developed 

 in man either as the result of surgical removal of the parathyroids or 

 because of their improper development. The symptoms in man are very 

 similar to those observed in laboratory animals, the only difference being 



that the muscular contractions are more likely 1" be tonic in charati 

 Certain symptoms that may develop during pregnancy or in the course 



of infections diseases or in newborn infants have also been found to be 



associated with degeneration of or hemorrhage into ihe parathyroid 

 (idiopathic tetany), and certain obscure nervous diseases in adults, 

 such as paralysis agitans, may possibly also be associated with changes 

 in this gland. Chorea, epilepsy, and eclampsia have likewise been 

 thought to In- associated with it. 



The parathyroid gland, besides influencing the nerve centers, has also 

 an influence on metabolism. The metabolic disturbances following parathy- 

 roidectomy are : <1 rapid emaciation and failure to grow ; 2 ;i tendency 

 to the production of glycosuria, often detected by finding that the assimila- 

 tion limit for carbohydrate is lowered page 652 ; and :; most definitely 

 of all, an interference with calcium metabolism, as illustrated by the failure 

 of the teeth and bones to calcifj properly. This interference with normal 

 metabolism led Kellogg and Voegtlin 81 to study the effect produced 

 parathyroidectomized animals by the administration of calcium. It was 



found that the symptoms were considerably ameliorated. These authors 

 Concluded from their results that the essential cause of tetany : 

 deficiency Of calcium in the blood. It is possible however that the h 

 flcial action of calcium salts in this condition is that it d jes the 



excitability of the nervous system, an action which it is known to 

 possess. 



