s 



MALIGNANT EDEMA. 471 



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

 as roweling, ca,stration, and phlebotomy, which have become infected 

 with septic matter, soil, or unclean instruments. In the patho- 

 logical laboratory of the Bureau of Animal Industry the organ- 

 ism has also been obtained 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 blacldeg 

 vaccine m 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, thL-^ 

 organism is widely distributed and found in ordinary garden soil, 

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

 may 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 through the blood channels 

 to other parts of the body. 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 these 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 ciistration, 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. 



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

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

 and lies down in shaily and quiet places. If forced to move about, 

 the hind legs are drawn forward with a peculiar, stiff, dragging 

 movement, and there may be slight muscular trembling over all the 

 body, which becomes nmre intense as the disease progresses. "Wlien 

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

 the ground completelj' exhausted. Breathing becomes fast and 

 I^ainful, with frequent spasmodic jerks. 



The jjulse is quick and weak and the temperature is 106° to 107° F. 

 An edematous, doughy, and painful swelling appears at the point of 

 infection. This tumefaction spreads more and more, and crackles 

 on pressure. In case of an open wound, a fetid liquid and frothy 



