40 INTERNAL SECRETION 



the muscular spasms become more frequent and more intense ; 

 the animal rubs its snout, walks stiffly, and steps on the dorsum 

 of the paws. Frequently, there is a peculiar position of the paws 

 caused by tonic contraction, accompanied by diffuse clonic con- 

 tractions in different groups of muscles and, more particularly, 

 by the tremor of an extremity, due to lightning contractions. 



As the condition progresses, the clonic contractions spread 

 to nearly all the muscles of the body, when what is known as 

 a tetanic seizure comes on. It begins with a marked increase 

 in the respiratory and cardiac activity, and the temperature rises 

 to 41-42.5 C. (about 106-108 F.). The animal suddenly lies over 

 on its side and the breathing becomes extremely rapid, interrupted 

 by occasional deep convulsive inspirations ; or there is opis- 

 thotonus and tetanic convulsion of the diaphragm and the animal 

 dies from suffocation. Very frequently, however, there is spon- 

 taneous recovery even after severe attacks ; the cardiac and 

 respiratory activity become gradually slower; the temperature 

 sinks and may become even subnormal ; and a condition of 

 extreme weakness supervenes. After an interval varying from 

 one to forty-eight hours, the fibrillary contractions again become 

 stronger and a fresh attack comes on. After several attacks the 

 animals become very emaciated and, ten to fourteen days after 

 operation, they die. Apart from pneumonia, which is frequent, 

 the post-mortem finding is negative. 



Gozzi has recently described severe and extensive lesions of 

 the liver, which he found regularly in dogs after extirpation of 

 the parathyroids, and which affected the vessels as well as the 

 cells. 



A slightly aberrant form of tetany is observed in young dogs. 

 There may be clonic contraction of the muscles in certain regions, 

 but the seizures are more frequently characterized by tonic con- 

 tractions of the muscles of the glottis, respiratory apparatus and 

 extremities. The body, especially in the hinder extremities, is 

 stiffly extended and this seal-like attitude persists when the 

 animal is held away from the ground. After frequent repetition 

 of these seizures, a spastic paralysis develops in the hinder 

 extremities and these are dragged along the ground when the 

 animal tries to walk. The paralysis spreads and the animal dies. 



Complete thyroidectomy produces an extremely acute tetany 

 in rabbits (to remove all parathyroids it is necessary to extirpate 

 the whole or the major portion of the thyroid). For one to three 

 days the condition of the animal remains unchanged ; then there 

 is quivering of the masseters, accompanied by single clonic 

 contractions in various muscles ; there is a sudden and violent 

 tetanic seizure and death from suffocation results. Sometimes 

 the extirpation of the external parathyroids only is sufficient to 

 bring about a fatal tetany though it more frequently provokes 

 the chronic form. Frequently, however, and especially in the 



