Section II. 

 DISEASES OF THE HEART. 



1. Palpitatio Cordis. 



{Tachycardia, Hyperkinesis cordis.) 



A purely nervous palpitation which is independent of 

 organic heart diseases appears in domestic animals onlj^ very 

 rarely, but it has been observed preferably in highbred and 

 very vivacious horses and dogs, also once, by Bredo, in a four- 

 year-old cow. 



The greater portion of cases reported under this name in veterinary 

 literature must undoubtedly be classed with spasm of the diaphragm 

 or with organic heart diseases. Older authors commonly considered 

 spasm of the diaphragm as palpitation, and more recently organic heart 

 diseases which, especially after external influences, also may give rise 

 to similar spasmodic attacks, have not been duly considered in the inter- 

 pretation of symptoms. 



Etiology. An abnormally increased action of the normal 

 heart muscle may be caused either by an excessive irritation 

 or by an increased irritability of the N. sympathicus or by 

 paralysis of the N. vagus. The first mode enters into con- 

 sideration in those cases in which palpitation occurs after 

 violent psychic irritation, after fright, in case of fire, on falling, 

 after railroad transportation, or from over-exertion ; similar 

 conditions may however also lead to acute cardiac dilatation 

 or to acute heart weakness. A congenital morbid irritability 

 of the nervous system in nutritive disturbances, in hemorrhages, 

 in Basedow's disease, must in certain cases also be brought 

 into causal relation with palpitation. Then inflammation or 

 degeneration of the N. vagus (in chronic lead poisoning) 

 usually leads to tachycardia. Finally palpitation sometimes 

 persists after influenza (Pr. Mil. Vb.). 



Martius considers palpitation as a purely secondary phenomenon 

 which is always based upon a paroxysmal acute heart dilatation, i. e., 

 an organic heart disease. 



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