INFECTIOUS DISEASES 327 



always a wound infection disease ; therefore infection in the majority 

 of instances gains entrance through injuries or wounds. 



Lesions. — The first manifestation of wound infective malignant 

 edema consists of a marked tumefaction of the surrounding structures. 

 The tumefied tissues will be found edematous and deep-seated gas may 

 be detected by palpation. If the tumefied structures are incised a 

 bloody serum having a fetid odor will escape. The extent of the 

 swelling varies and depends upon the density of the tissue and the 

 virulence of the infection. In some cases the tumefaction extends 

 some distance from the infected wound. By autopsy these tumefac- 

 tions are found to be a mass of infiltrated disintegrated tissue, having 

 a very offensive odor. The sub cutis and muscle are extensively in- 

 filtrated with a semi-solid gelatinous material. The related lymph- 

 glands are usually tumefied and edematous. The visceral organs 

 usually have a parboiled appearance. 



In cases of malignant edema succeeding castration or other opera- 

 tions which permit of extension of infection to the peritoneum, the 

 lesions consist of peritonitis in which the peritoneal blood-vessels are 

 engorged and there are varying quantities of a serosanguineous fiuid 

 in the peritoneal cavity. The connective tissues in the inguinal 

 region are usually slightly infiltrated. The spleen may be dark in 

 color. 



Metritis due to the B. edematis maligni is characterized by a deep 

 red color of the uterine mucosa and a bloody effusion into the uterine 

 cavity. The uterine walls are infiltrated and the entire uterine struc- 

 ture is more or less degenerated and emits a foul odor. 



Symptoms. — The symptoms evidenced by wound infective malig- 

 nant edema are: depression, disturbance of locomotion,, inappetence, 

 edematous swellings and rise of temperature. These symptoms usually 

 develop in from twelve hours to two days after the wound is infected. 

 In peritoneal malignant edema the affected animal has a "tucked up" 

 appearance and manifests pain when the abdomen is palpated. There 

 will be rise of temperature and inappetence. Septic metritis is evi- 

 denced by an arched back, bloody discharge from the genitals, high 

 temperature and anorexia. Malignant edema is fatal in a large per- 

 centage of cases. The course of the disease is short ; the animals suc- 

 cumb on the second or third day. 



Treatment.- — Treatment of malignant edema in swine has not proved 

 successful. A preventive vaccine has been experimentally demon- 



