Diseases of Arteries. 349 



are as varied as the organs affected and will be noted below in the 

 special article on thrombosis and embolism. 



Chronic arteritis. Atheroma. This is an indolent inflam- 

 mation supposed to result mainly from strain and overwork, and 

 manifested by thickening and clouding of the serosa, with cell 

 proliferation, softening and fatty degeneration. The diseased 

 substance becomes soft, pultaceous, slightly greasy, and under 

 molecular degeneration it breaks up and is even in part washed 

 on in the blood stream. Other degenerations may occur in the 

 inflamed walls of the artery. The exudate may become organ- 

 ized, constituting fibrous thickening. It may become the seat of 

 calcareous degeneration. It may yield to the blood pressure, be- 

 coming slowly attenuated (atrophy), and even dilated (aneurism 

 by dilatation). As a cause of chronic internal arteritis in the 

 horse should be named the presence in the vessels of the larva of 

 the strongylus armatus. The posterior aorta and anterior mesen- 

 teric artery which are the most commonly infested by these para- 

 sites are frequently attenuated, dilated and calcified in this con- 

 nection. 



Treatment. Acute arteritis should be treated like any other 

 local inflammation, by rest, soothing applications (fomentations, 

 astringents, icebags), and alkaline salts. It has been proposed 

 to manipulate the affected artery and contained thrombus, but 

 this can onl}^ tend to block the smaller arteries farther on, and 

 perhaps with even more injurious results. The liberal use of 

 alkalies on the other hand, if effective in dissolving any portion 

 of the clot, returns this to the blood stream in a condition that 

 will not endanger further embolism. The agents usually em- 

 ployed are carbonates of ammonia, potash or soda, and iodide of 

 potassium. 



