Etiology, Anatomical Changes. 1105 



These experiments render it not impossible that the inflam- 

 mation of the arterial wall iisnally develops under the influence 

 of certain chemiAl substai],ces or bacterial toxins. In human 

 medicine the excefcive use #f alcohol and tobacco, gout, Bright 's 

 disease, sj^Dhilis and metric poisoning are believed to stand in 

 relation in this respect. /^ 



Circumscribed eHP)arteritis very frequently arises in 

 horses under the influence of the Sclerostomum vulgare, prefer- 

 ably in the Arteria mesenterica anterior, not rarely in the aorta 

 or in the arteries of the extremities, exceptionally also in the 

 arteries of the other organs, including those of the heart 

 (Cadiot, Piot-Bey, Magnin). A similar influence is exerted by 

 the much less frequent Spiroptera sanguinolenta upon the aorta 

 of the dog, the Filaria Poelsi (Yryburg) or the Filaria Blini 

 (Carougeau & Marotel) upon the aorta of buffalo in Sumatra, 

 sometimes also upon that of cattle, without, however, causing 

 disturbances in the health of the animals. In cattle the inflani- 

 matory process is sometimes produced by foreign bodies (Sei- 

 berth). 



The virus of periarteritis nodosa in axis-deer could not be determined by 

 Liipke (the cocci which were repeatedly demonstrated in the blood and in the 

 diseased organs failed to produce the disease in small experiment animals). 



Anatomical Changes. In the incipient stage of the process 

 small, elongated or round, white or pale yellow, shallow eleva- 

 tions are found on the intima of the artery, which are most 

 numerous at those places at which the blood is thrown most 

 strongly against the wall, for instance at the turns of main 

 arteries, at places where branches are given off, etc. Corre- 

 sponding to these spots there exists, in horses and cattle, a pro- 

 liferation of the connective tissue, with a slight fatty degenera- 

 tion and calcification, in dogs the media and intima are atro- 

 phied and there is fatty and calcareous degeneration. Cavity 

 formation is rare, ulcerous destruction (atheromatous ulcer) 

 is completely missing (Lyding). Eventually the arterial wall 

 bulges and becomes rigid in consequence of diminished elas- 

 ticity. 



Calcification of the aortic wall occurs frequently in old 

 birds, less so in horses and cattle; in the latter it is found, 

 according to Lignieres, as a sequel of the Argentinian disease 

 known under the name of "Enteque," not only in the walls of 

 the aorta but also in those of the smaller arteries. In pigeons 

 the Hypodectes oolumbarum which exists as a parasite in the 

 vicinity of large vessels may give rise to similar changes. 



In periarteritis nodosa the arterial wall is thickened, consequently the vascular 

 lumen is smaller or entirely obliterated. A nodose thickening of the arterial wall 

 is observed in varying degree. The lumen is narrowed or obliterated or it is bulged 

 out and often contains thrombi. 



Symptoms. A generalized arteriosclerosis can, in a fairly 

 advanced stage be recognized only if the vessels which are imme- 



Vol. 1-70 



