Course. Diagnosis. 227 



on the course of the disease, and such cases usually terminate 

 fatally. 



In the favorable cases the swellings after reaching a certain 

 degree retrogress either rapidly or gradually. Frequently, 

 however, the improvement is only temporary, as the condition 

 later becomes aggravated again, and with such variations the 

 disease may run for several weeks until finally the animal recov- 

 ers. The average duration of the mild cases may be placed at 

 about two weeks, although it may occasionally extend over a 

 period of 6 to 8 weeks. In cases where large areas of the skin 

 become necrotic it may require several months until a definite 

 recovery takes place, and even in such cases the recovery is not 

 complete, as in place of the extensive wounds contracted scars 

 remain which interfere with the function of the extremities, and 

 thereby reduce the value of the horse for work. 



In fatal cases the duration of the disease also varies. There 

 are cases in which the swellings form with such rapidity and 

 become so extensive that death ensues in from 3 to 5 days (Dern- 

 bach saw a horse in which death occurred after 7 hours as a 

 result of a hemorrhage in the neighborhood of the medulla 

 oblongata). Complications (gangrenous pneumonia, enteritis,' 

 pyemia, septicemia) usually develop only after the swellings 

 have progressed extensively and have produced functional dis- 

 turbances as well as necrotic processes; up to that time, how- 

 ever, usually 1 or 2 weeks have elapsed. If any of these com- 

 plications have appeared death always ensues after several 

 days. 



Diagnosis. Eecognition of the disease is difficult as a rule 

 only when it is associated from the beginning with fever, or 

 when edematous swellings and hemorrhages appear in the 

 course of a preceding febrile affection. Edematous infiltrations 

 may develop from local causes (phlegmons, lymphangioitis) 

 as well as in general infectious diseases (anthrax, malignant 

 edema) ; they may, however, be distinguished from the swellings 

 of purpura hemorrhagica by the diffused borders and by the 

 localization of the inflammatory processes. Besides this the 

 swellings in purpura hemorrhagica are usually sharply circum- 

 scribed and occur in most instances symmetrically on both sides 

 of the body ; they also appear after or simultaneously with the 

 development of petechiae on the nasal mucous membrane. In 

 the early stages of the disease urticaria may also come under 

 consideration, as it is sometimes manifested by extensive and 

 shairply circumscribed swellings of the skin; however, in this 

 affection the petechiae are absent on the nasal mucous mem- 

 |)rane, and the eruptions disappear entirely after a short time. 

 Acute glanders may likewise resemble purpura hemorrhagica 

 to some extent, especially in cases in which the swelling of the 

 nasal mucous membrane and its surrounding tissue, as well as 

 of the extremities and abdomen develops rapidly; however, in 



