458 INFECTIOUS ANEMIA IN HORSES 
These seem to be the most constant symptoms in the acute type which 
lasts from a few to fifteen or more days. The mortality is not high 
in the first attack. Apparent recovery seems to take place but usually 
subsequent attacks occur or a progressive anemia with emaciation 
follows. Death follows in from a few weeks to many months. In 
some cases years may elapse. The acute stage is usually followed by 
the chronic form. The febrile attacks appear at variable intervals. 
and last for a few days. The mucous membranes become pale. 
The urine contains small quantities of albumin. Edematous swellings 
Fic. 108. HORSE SUFFERING WITH SWAMP FEVER (after Udall and Fitch). 
of the extremities may occur. The mortality of the disease is very 
high. Few if any infected animals completely recover from it. 
Morbid anatomy. The anatomical changes are subject to great. 
variation. In the acute type the heart shows sub-serous and sub- 
pericardial hemorrhages. These may be either single or multiple 
and are either petechie, ecchymoses or suffusions. The endocardium 
also is often studded with petechiz and the chorde tendinex are 
enlarged and sometimes edematous. According to Carré and Vallée 
this edema may extend to the valves. In the chronic form the myo- 
