SOLTDUNGULA 371 



domestic animals. Atheroma in the horse is always secondary. 

 To be sure, one observes an idiopathic chronic endo-arteritis in 

 many abdominal arteries of the horse, which, however, never 

 exhibits indications of atheromatous degeneration. 



11. In consequence of its position the worm-aneurism of 

 horses is not open to physical examination, and on that account 

 cannot be diagnosed by physical signs ; moreover, it offers no 

 characteristic symptoms. Its termination by rupture is 

 extremely rare, the aneurisms of the abdominal aorta being 

 more disposed to rupture than those of the anterior mesenteric 

 artery. Of eighteen cases of known perforation, fifteen opened 

 into the peritoneal cavity, and three into the bowel. The 

 dangerous symptoms of' the worm-aneurism are exclusively due 

 to embolism and thrombosis of the affected artery, arising from 

 the parietal clot. The latter becomes especially dangerous 

 through its increasing size and the softening which often 

 accompanies it. The absorption and shrinking of this parietal 

 clot, be it organised or not, is materially assisted by the high 

 pressure to which it is exposed. 



12. The very marked symptoms of vascular obstruction the 

 sero-hsemorrhagic intestinal infarct in embolism and thrombosis 

 of the mesentric arteries are easily explained by paralysis of 

 the muscular coat of the intestine, by the absence or paucity of 

 valves in the portal vein, by the readiness with which meteor- 

 ismus (or flatus) arises, especially in herbivora, and by the loose 

 consistence of the intestinal walls or villi. 



13. The occlusion of the intestinal arteries, especially that 

 arising suddenly, always has for its result a partial or complete 

 paralysis of the portion of bowel which they supply. The 

 palsy of the intestine causes the forward movement of the 

 intestinal contents to cease, a stoppage of the faeces, a hin- 

 drance to the discharge of faeces and gas, and also that exceed- 

 ingly dangerous formation of gas (within the intestinal tract) 

 which in the herbivora is so abnormal, both quantitatively and 

 qualitatively. 



14. In embolism and thrombosis of the mesenteric arteries 

 ihe symptoms during life are entirely identical with those 

 observed in the so-called colic of horses, as has been determined 

 by numerous observations. The partial paralysis of the bowel, 

 which is brought on by the embolism and thrombosis of the 

 mesenteric arteries, forms in great part the chief and leading 

 feature of the series of symptoms known as the " colic " of 



