460 DISEASES OP CATTLE. 



wounds, as roweling, castration, and phlebotomy, wMch have become 

 infected with septic matter, soil, or unclean instruments. The organ- 

 ism 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 essen- 

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

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

 develop 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 may be 

 brought to the surface of the soil by growing plants, rains, winds, or 

 burrowing insects and rodents. In animals that have succumbed 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, although 

 refractory to experimental inoculation, suffer from natural infection 

 while calves are susceptible to both of these methods of exposure. 

 (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 organisms 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. 



Symptoms. — 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 stiff dragging 

 movement and there may be slight muscular trembling all over the 

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

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

 ground completely exhausted. Breathing becomes fast and painful, 

 with frequent spasmodic jerks. 



The pulse 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 will crackle 

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

 discharge is observed. The center of the swelling may appear soft 

 and jelly-like, while the margin is tense, hot, and painful. The symp- 

 toms increase rapidly, resulting in coma and death. 



Lesions. — After death the fat and subcutaneous tissues surrounding 



