MALIGNANT EDEMA 285 



Infected premises, barns, sheds, stables, etc., should be 

 thoroughly disinfected by using chlorid of lime, or an abun- 

 dance of quicklime in the form of whitewash or dry. The 

 carcass should not be skinned, the flesh should not be fed to 

 dogs or swine, and the use of the milk forbidden. 



MALIGNANT EDEMA. 



Definition. — Malignant edema is an acute, fatal, infectious 

 disease, characterized by the formation of edematous swellings, 

 which later become emphysematous and occur in the region of 

 a wound infected with the specific anaerobic Bacillus cedematis 

 maligni. 



Occurrence. — The disease is widely distributed. It affects 

 mostly horses, following accidental or surgical wounds. In 

 cattle it occurs from obstetrical operations, and in sheep may 

 result from cuts received during shearing. In the United 

 States it is one of the commonest wound-infection diseases 

 extant. 



Etiology. — The Bacillus cedematis maligni, which is found in 

 both the rod and spore stages in soil, manure (droppings), 

 dust, decomposing vegetable matter and poluted water. 



Natural Infection. — Horses and sheep seem most susceptible 

 to the infection, while cattle and swine offer more resistance. 

 The infection is always through a wound (surgical or acci- 

 dental) in the skin or mucous membrane. In practice malig- 

 nant edema most frequently follows surgical operations (poll 

 evil, castration, phlebotomy), the use of the unsterilized 

 hypodermic syringe, rough obstetrical manipulations, skin 

 cuts from careless shearing of sheep, etc. It may also follow 

 accidental wounds due to wood splinters, nails, or other pene- 

 trating objects which carry the infection. Feeding and in- 

 halation experiments with the bacilli and spores of malignant 

 edema gave negative results. The intact skin and mucous 

 membrane are not infectable. Infection through a necrotic 

 area (ulcer) is probable. Normally granulating wounds are, 

 however, very resistant to infection. Inoculations with pure 

 cultures are not successful unless phagocytosis is overcome by 



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