

THE PARATHYROID GLANDS 527 



They had no opportunity of studying in their own experiments the 

 effect of pregnancy and lactation on the postoperative symptoms, but point 

 out that many observers have noted that these conditions appear to aug- 

 ment the symptoms of parathyroid tetany. Carlson (c) (1913) found that 

 late pregnancy in dogs accelerates and intensifies the tetanic disturbances 

 in the majority of cases, 'but 'that in 'cats it does not appear to have any 

 influence. 



Massalgia (1916) removed three parathyroids from each of two female 

 pups and found that this did not interfere with their development. When 

 they became pregnant, however, both developed tetany. This the author 

 compares with eclampsia, and suggests parathyroid extract as a therapeutic 

 remedy. 



Thompson and 'Leighton showed that trophic disturbances may arise, 

 without acute symptoms, from an incomplete loss of parathyroid 'tissue, 

 and this has been frequently confirmed. They gradually destroyed the 

 glands by ligation in twenty dogs, and in many observed only chronic 

 trophic changes, without serious damage to the thyroid. 



Symptoms of Tetania Parathyreopriva. Considering the relationship 

 believed by many to exist between the parathyroid glands and idiopathic 

 tetany in the human subject, it is important to become familiar with the 

 clinical picture exhibited by animals following parathyroid extirpation. 

 The symptoms differ in different animals, and in the same animal at dif- 

 ferent times. They are most severe in dogs and foxes. They have been 

 described by many observers, Schiff, Horsley, MacCallum, Paton and 

 Findlay, and others, some emphasizing one feature, some another, accord- 

 ing as these happened to be exhibited more or less prominently in their 

 respective subjects. 



Based upon observations on twenty dogs, MacCallum gives a good de- 

 scription of their behavior after complete extirpation of the parathyroids. 

 Usually the animal has recovered perfectly from the anesthetic the next 

 day. If watched carefully, it is seen to begin to show signs of restlessness 

 and anxiety. When one places the hand on the muscles of the head or 

 shoulder, one feels feeble fibrillary tremors; these become more distinct, 

 so that they are evident to the naked eye, and the animal may pass rapidly 

 into a condition in which all the muscles are in rigid spasm ; but as a rule 

 the tremors are accompanied by clonic, chorea-like movements of the whole 

 limbs or segments of the limbs, and at this stage, if the animal be laid on 

 its side and a suitable lever attached to either the fore or hind leg, a 

 characteristic tracing, showing the clonic and tonic contractions, may be 

 obtained (Fig. 3). 



The dog is able to walk at first, but somewhat stiffly and awkwardly ; 

 then he may suddenly fall to the floor, or he may show a staggering, 

 cerebellar gait, superimposed on the dancing movements of his limbs. 

 "Sometimes, in walking about or climbing stairs, the dog suddenly 



