PISEASES OF AETERIES 263 



acute or chronic, aseptic or septic (purulent). According to 

 its origin, it may be traumatic or hematogenous. 



Is arteritis a common swrgical disease ? 



It is comparatively rare, especially the chronic form, also 

 known as chronic deforming or atheromatous arteritis. 



Which variety of arteritis is of most practical interest ? 

 Acute septic or purulent arteritis. 



How is an acute septic arteritis produced ? 



The arterial walls are infected with pus-producing bac- 

 teria as follows : 



1. In septic diseases an infected embolus may become 

 lodged in an artery and excite a purulent inflammation of the 

 internal coats, which are swollen and infiltrated with pus 

 cells. 



2. A purulent inflammation of the surrounding parts may 

 spread to the adventitia and a purulent periarteritis results. 



3. The intima, some way or other, becomes injured and a 

 purulent thrombus forms at that point, a condition termed 

 purulent endarteritis. 



What is chronic deforming arteritis ? 



It is a chronic endarteritis followed by fibrous changes, 

 fatty degeneration, cheesy collections and calcareous deposits 

 in the arterial walls, as a result of which the walls of the 

 artery become hard and inelastic ; may even rupture the 

 lumen of the vessel ; may become narrower or even oblit- 

 erated. 



In which animals is chronic arteritis exemplified ? 



In the horse it is the result of the presence of the 

 strongylus armatus in the mesenteric arteries. 



