246 BLACK LEG 
the omentum, mesentery and in the neighborhood of the kidneys. 
The mucous membrane of the stomach and small intestines is fre- 
quently swollen, congested and infiltrated with hemorrhages, in which 
case the contents of the intestine are bloody. The liver is hyperemic, 
but the spleen is usually normal. 
In the thoracic cavity, the pleure in the neighborhood of the swollen 
parts of the skin and mediastinum are sometimes hemorrhagic. The 
pleurze may also show large ecchymoses, in which case the thoracic 
cavity contains a sero-sanious exudate. Hemorrhages are sometimes 
present in the lungs, pericardium, myocardium and under the endo- 
cardium. The muscular tissue of the heart is very soft, but the other 
muscles show only slight changes. The mucous membrane of the 
bronchi is sometimes hyperemic and sprinkled with hemorrhages. 
The blood is of a normal color and coagulates readily, The fluids 
of the muscles have, according to Feser, an acid reaction, and the flesh 
becomes rapidly putrid. The bacilli of black leg are found only in 
small numbers if at all in the blood during life, but abundantly a few 
hours after death. They are numerous in the local lesions. In 
swine, it is reported that the lesions are restricted to a severe inflam- 
mation of the throat. 
Diagnosis. Black leg is diagnosed by the symptoms, especially the 
local swellings, the lesions found on post mortem and the finding of 
B. Chauvaei. This can be done by making cultures in deep agar or in 
the fermentation tube, from the local lesions or by the inoculation of 
guinea pigs. The organisms are also found in microscopic prepara- 
tions from the lesions. There are no satisfactory specific tests for 
diagnosing this disease. The serum of a cow affected with black leg 
is reported to agglutinate the bacilli in dilution of about 1 to 300. 
The serum from a healthy cow agglutinated in dilutions of less than 
1 to 12. 
Black quarter is to be differentiated from anthrax, septicemia 
hemorrhagica, malignant edema and various forms of poisoning. 
Usually the localized subcutaneous lesions are sufficient to differen- 
tiate black quarter from these other affections. It often happens, 
however, that post-mortem changes have so modified the carcass 
before it can be examined that the diagnosis is questionable. In this 
and all doubtful cases it is necessary to resort to a more definite 
method or methods, such as the microscopic examination, cultures and 
animal inoculation. These methods are described under the respec- 
tive diseases. 
