38 Malignant Edema. 



Diagnosis, In cattle malignant edema may be mistaken for 

 blackleg. Malignant edema is indicated by the appearance of 

 the disease in localities where blackleg is not prevalent, further 

 by the advanced age of the patient, the occasional localization 

 of the swelling in parts which are poor in muscle tissue, and by 

 the relatively severe affection of the connective tissue com- 

 pared with the slight involvement of the muscles. Parturient 

 apoplexy is differentiated from malignant edema by the absence 

 of the crepitating swelling, and the different bacteriological 

 findings. 



In horses and sheep the development of a crepitating swell- 

 ing under febrile manifestations indicates malignant edema. 

 The crepitation distinguishes the disease from edema, which 

 often resembles it very closely, as well as from the inflammatory 

 edema which is caused frequently by a streptococcus infection 

 following injuries ; whereas in the simple subcutaneous emphy- 

 sema there is in addition to the pre-existing skin or lung injury 

 an entire absence of febrile symptoms. On post mortem care 

 should be taken not to mistake the emphysema caused by putre- 

 faction with the crepitating swelling which develops during 

 life. (For differential diagnosis regarding the bacilli, see p. 20.) 



Treatment. The only possible method of treating the 

 patients consists in incising the swellings as they are forming 

 in one or several places. This is to be followed by squeezing 

 out the serous fluid and by thorough disinfection of the wounds ; 

 at the same time it is advisable to inject disinfecting substances 

 subcutaneously into the tissue immediately surrounding the 

 swelling. 



While the disinfectant treatment is practically without 

 effect upon the spores of the edema bacilli, it indirectly prevents 

 the germination of the spores by destroying the foreign bacteria 

 which entered the wound and also prevents the multiplication 

 of the bacilli. 



Prevention. In order to prevent the occurrence of the 

 disease, wounds of the skin and mucous membranes should be 

 guarded against contamination with dirt. Those wounds which 

 have already become contaminated should be disinfected, 

 whereas, after difficult parturitions in which the genital pas- 

 sages have been injured a thorough irrigation of the vagina 

 and uterus will prevent the disease. 



Immunization. Experimental animals may be immunized against 

 virulent infections by injections of spore-containing tissue fluids which 

 have been heated for 7 hours to 92° C. (Leclainche & Vallee) ; by bouil- 

 lon cultures heated for 10 minutes to 105-110° C, also by filtrates of 

 the edematous fluid, or through the toxins contained therein (Roux & 

 Chamberland) ; further by blood serum of immunized animals which 

 have received repeated injections of virulent material (Duenschmann, 

 Leclainche & Morel). These inoculations protect only against malignant 



