252 MALIGNANT EDEMA 
tumefaction. The mucous membrane of the intestinal canal may 
show signs of acute catarrh. The lymph glands are swollen. The 
lungs are hyperemic and for the most part edematous. The muscular 
system of the heart shows usually a high degree of parenchymatous 
degeneration. The blood clots very little. The body decomposes 
quickly. The fluid pressed out of the crepitating tumor contains 
edema bacilli in great number, associated possibly with other bacteria. 
The presence of the bacilli of malignant edema in the tissues of a 
dead animal does. not of itself prove that it died of this disease. 
These bacilli appear very often in the intestinal contents of animals 
which feed on plants. They often pass through mucosa of the intes- 
tine into the blood stream at the time of death. They may multiply 
in the tissues, especially when the blood remains fluid for some time. 
Diagnosis. Malignant edema is diagnosed by the symptoms, 
lesions and bacteriological examination. The blood of immune ani- 
mals agglutinates the bacilli in dilutions of from 1 to 30 to 1 to 3000. 
There are no satisfactory sera or other specific reactions. It is to be 
differentiated from black leg, anthrax and inflammatory edemas. 
As distinguishing malignant edema are the occurrence of the disease 
in a region where symptomatic anthrax is not native. Often the 
advanced age of the patient excludes black leg. The occasional 
localization of the tumor on parts of the body poor in muscle, and the 
insignificant affection of the muscular system in comparison to the 
severe affection of the connective tissue are observed. 
In horses and sheep the development of a crepitating tumor with a 
fever indicates malignant edema. ‘The crepitation distinguishes the 
disease from anthrax edema as well as from the inflammatory edemas 
often following wounds and caused by streptococci. In simple sub- 
cutaneous emphysema, following skin wounds, fever rarely occurs. 
Finally care must be taken that on post mortem a simple emphysema 
caused by putrefaction is not confused with a crepitating tumor 
formed during life. 
Prevention. In the prophylaxis of the disease the wounds of the 
skin and the mucous membrane are to be kept from infection from the 
soil. Wounds that are already infected are to be disinfected. After 
difficult parturition in which the genital passages have been injured a 
thorough cleansing of the latter and of the uterus will usually check 
the development of the disease. Experimental animals can be 
immunized against the virulent infection by injection of tissue juices 
