RUPTURE OF THE HEART. 



In the lower animals ruptures of the heart have been observed 

 as the result of (a) extraordinary exertion, (b) violent concussion, 

 and (c) ulceration and degeneration. The rupture of the fatty 

 heart in the lower animals is not common. 



Rupture during severe exertion occurs in the perfectly 

 healthy heart. The ruptures take place in the weakest point, and 

 most commonly in the fibrous ring which encircles the base of the 

 heart and attaches the great aorta. This is occasionally seen to 

 happen in very spirited horses during a severely contested race or 

 when a heavy load is being dragged up hill. Percivall mentions 

 the case of a horse at a Woolich racing meeting, which had just 

 lost a heat by half a head and which died just after passing the 

 winning post, with ruptured right auricle. 



Cases occur during coitus (Hering), tympany (Anacker, 

 Mayer, Perdan) and operations (Stockfleth). 



Rupture from Concussion more frequently implicates the 

 muscular walls which have not the same power of resistance when 

 they receive the blow in a relaxed condition. Parker met with a 

 case of rupture of the right auricle at its base or at the line of its 

 union with the ventricle. The subject was a pony which ran 

 away down hill and struck his right shoulder violentlj^ against a 

 cart wheel. In other instances the rupture takes place in the 

 posterior vena cava, and particularly if its walls have been the 

 seat of disease. Gamgee found rupture of the commencement of 

 the azygos vein in oxen killed by pithing in the slaughter houses 

 of Ferrara, and Professor Maffei subsequently found that out of 

 3095 oxen killed in these abattoirs 57 had this vein ruptured. 

 Gamgee' s explanation of the occurrence is that "the instant the 

 animals are pithed the wal's and contents of the chest become 

 paralyzed, the heart becomes an inert bag filled with fluid, the 

 jerk of which as the animal falls, causes rupture of the contain- 

 ing vessel at its weakest part and this is in truth the vena azygos 

 whose walls are thin and only protected externally by the pleura." 

 Hertwig gives other cases resulting from falls. 



Perforation of the heart from ulceration is sometimes seen 



343 



