INFECTIOUS ANEMIA IN HORSES 459 
cardium may be discolored and spotted with rose colored or grayish 
patches which are the remains of former hemorrhages. 
The spleen is usually enlarged. Udall and Fitch observed several 
where it appeared to be normal in size. In some cases the spleen is 
harder than normal due undoubtedly to the increase in the connective 
tissue stroma. The surface of the spleen is sprinkled with petechiz 
and ecchymoses. Microscopic examinations of properly stained 
sections show that the splenic pulp is congested and that in many 
areas the trabecule are apparently enlarged. 
The liver is often enlarged and sprinkled with petechiz on the 
surface. Carré and Vallée report that it may become so friable that 
it may rupture if the animal suddenly lies down. Jn the acute form 
petechize and ecchymoses are present on the surface of the lungs. 
The kidneys are occasionally congested with petechial hemorrhages. 
Parenchymatous degeneration is noted especially in the cortical por- 
tion. Carré and Vallée state that small abscesses are sometimes 
found in the cortex. Sub-serous hemorrhages are present in the 
intestines. The mucous membrane is often hemorrhagic. These 
changes are present in both the large and small intestines. 
The peritoneum is usually congested and may show petechiz and 
ecchymoses. The abdominal cavity usually contains varying amounts 
of more or less sanguineous fluid. 
The long bones, particularly the femur and humerus, show the 
most pronounced lesions. In the proximal ends of these bones the 
marrow is a brownish or a bright red either wholly or in circumscribed 
portions. The spongy bone marrow of the ribs and vertebrae show 
similar changes. These discolored areas are not due to hemorrhages 
as would be supposed on microscopic examination. But they are as 
stated by Hutyra and Marek due apparently to the increased activity 
of the blood forming elements of the red marrow. The spongy bone 
marrow in some areas shows degeneration and congestion. 
The lymph glands, especially the mesenteric, are often enlarged, 
darker in color than normal and usually congested. There is, accord- 
ing to Mack, Udall and Fitch, an increase in the lymphocytes. The 
hemoglobin varies. 
* Diagnosis. Swamp fever is to be diagnosed by the symptoms 
which in conjunction with the high mortality, progressive loss in 
condition and the lesions are fairly conclusive. The positive diagno- 
sis is made by means of a blood inoculation into solipeds. Horses 
