478 DISEASES OF CATTLE. 



MALIGNANT EDEMA. 



Malignant edema, also termed gangrenous septicemia, is an acute 

 inflammatory disease of domestic and wild animals, resulting from 

 the introduction of a sj^ecific organism into the deep connective tissues 

 of a susceptible animal and proving fatal in many instances within 

 24 to 48 houi-s. The disease may be inoculated from one animal to 

 another, but only by inserting the virus deeply below the skin. It 

 is infrequently met with in cattle, but may follow operating wounds, 

 as roweling, castration, and phlebotomy, which have become infected 

 with septic matter, soil, or unclean instruments. The organism has 

 also been obtained in this laboratory from the infected muscles of a 

 calf that was supposed to have died of blackleg, and, as a result, all 

 blackleg virus is thoroughly tested before it is made into blackleg 

 vaccine in order to exclude the malignant edema organism. The 

 essential cause of malignant edema is a long, slender, motile, spore- 

 bearing bacillus, resembling the bacillus of blackleg, and which can 

 develop only in the absence of the atmosphere. Unlike the bacilli of 

 anthrax and blackleg, which are confined to certain districts, this 

 organism is widely distributed and found in ordinary garden soil, 

 foul water, and in the normal intestinal tract of the herbivora. It 

 uuiy be brought to the surface of the soil by growing plants, rains, 

 winds, or burrowing insects and rodents. In animals that have suc- 

 cumbed to the disease the germ is confined to the seat of infection, but 

 a few hours after death it may migrate to other parts of the body 

 through the blood channels. The bacillus may attack man, horses, 

 asses, goats, sheep, pigs, cats, dogs, and poultry. Adult cattle, al- 

 though refractory to experimental inoculation, suffer from natural 

 infection, while calves are susceptible to both of tl^se methods of ex- 

 posure. (Kitt.) The introduction of the bacillus into abrasions of 

 the skin and superficial sores rarely does any harm, because the germ 

 is quickly destroyed by contact with air. If, however, the organ- 

 isms are inserted deeply into the subcutaneous tissues of susceptible 

 animals, they quickly develop, producing a soluble poison, which is 

 the fatal agent. 



In lamb-shearing season, or after docking or castration, the mor- 

 tality is higher among these animals because of wounds inflicted at 

 such times. The application of antiseptics to wounds thus made will 

 reduce the percentage of deaths to a minimum. 



Symftonw. — Usually the first symptoms are overlooked. In the 

 early stages the animal appears listless, disinclined to move about, 

 and seeks the shady and quiet places to lie down. If forced to move 

 about, the hind legs are drawn forward with a peculiar stiif dragging 

 movement and there may be slight muscular trembling all over the 

 body, which becomes more intense as the disease progresses. Wlien 

 driven, the animal shows signs of fatigue, ultimately dropping to the 



