482 DISEASES OF THE CIRCULATORY SYSTEM. 



pied the whole portion of the abdominal aorta situated in front 

 of the point of emergence of the renal arteries, and the diameter 

 of which was 12J centimetres. In most cases the three layers of 

 the vascular wall take part in the dilatation, and are affected by 

 atheromatous degeneration ; it -is thickened in some points and 

 atrophied in others, and contains here and there small calcareous 

 blotches. The contents of the aneurism are formed of fibrinous 

 clots which are ordinarily stratified ; these are sometimes organized, 

 at others softened or undergoing purulent destruction. According 

 to Koll, a spontaneous cure may be produced in our animals through 

 cicatricial retraction of those thrombi which are undergoing degen- 

 eration. The dilated aorta exerts a compression more or less great 

 upon the organs which are related to it : lungs, stomach, intestine, 

 liver, kidneys, etc.; it may even depress the vertebral column. 

 When the aneurism becomes ruptured the blood flows into the 

 pleura and peritoneum ; more rarely into the stomach (Vogel), the 

 intestine, or the rectum (Labat and Cadéac). 



Symptoms. Generally aneurism of the aorta is not marked by 

 any serious trouble. At times it produces death abruptly through 

 internal hemorrhage without any symptom indicating this fatal 

 ending, which is almost instantaneous, and is apoplectiform; it 

 occurs as a rule after energetic exertions : the animals are over- 

 come with dyspnœa, stagger, become weak and die. In some 

 cases we have observed alarming phenomena, which are marked 

 by paroxysmal attacks without any immediate fatal termination. 

 In a horse that had made violent exertion Lustig observed stagger- 

 ing of the hind quarters, abrupt falling, intense dyspnœa, and 

 epileptiform attacks, during which the neck and head were held 

 backward, with the legs stiff and extended ; within a quarter of 

 an hour the animal had completely recovered. In a horse affected 

 by aneurism of the pulmonary artery the same author has observed 

 vertiginous spells. Barrier has observed considerable emaciation 

 in a dog affected by aneurism of the posterior aorta, notwithstand- 

 ing that the appetite was preserved ; also an interference with the 

 respiration, which was increased under the influence of exercise ; 

 paralysis of the hind quarters (symptoms of heart- weakness).^ 



1 Aneurisms involving arteries of a small calibre are very rare in our animals. 

 Their rupture may be followed by a hemorrhage which may become rapidly fatal 

 when the blood escapes through a mucous membrane or flows into a splanchnic 

 cavity. — n. d. t. 



