330 ACUTE GENERAL INFECTIOUS DISEASES 



Etiology. — It is caused by the B. bipolaris suisepticum, a 

 bipoled organism which occurs in soil, food, drinking water, 

 and in the air passages and digestive tract of healthy swine. 

 It is possible that this germ is facultative and can live a 

 saprophytic existence. Swine, the resistance of which has 

 been reduced by intestinal parasitism (Ascaris lumbricoides, 

 Echinorhynchus gigas, Strongylus paradoxus), improper 

 food, exhaustion from long transports, etc., may become 

 predisposed. It is also probable that the virus of hog- 

 cholera may lower the resistance of an animal to such an 

 extent that the bipoled organism which enters it can assume 

 pathogenic properties. It is possible that the first appear- 

 ance of hemorrhagic septicemia in a healthy swine herd comes 

 from soil infection plus the lowered resistance of the animal. 

 However, once a pig is infected, through its discharges, the 

 bipoled organism having become pathogenic, can be elimi- 

 nated and infect other animals. As a rule, however, the 

 disease does not pass rapidly through a herd and, after attack- 

 ing a percentage of animals, dies out. 



Necropsy. — In the peracute form the lesions are typical of 

 hemorrhagic septicemia. Numerous small hemorrhages occur 

 in the skin, fat, in the serous and mucous membranes, kidneys 

 and myocardium. Larger hemorrhages are found in the peri- 

 renal connective tissue, in the mucous membrane of the renal 

 pelvis, urinary bladder, and in the brain. The lymph glands 

 show hemorrhagic swelling and there is a gelantinous infil- 

 tration of the subcutaneous connective tissue especially in 

 the region of the throat and neck. 



In the acute form the respiratory organs are attacked. The 

 lungs show multiple necrotic centers with a serous or hemor- 

 rhagic infiltration of interlobular connective tissue. With 

 this is associated a serofibrinous pleuritis. The peribron- 

 chial lymph glands are swollen and frequently traversed with 

 hemorrhages. 



The gastro-intestinal mucous membrane shows catarrhal 

 swelling and petechise. The surface is often covered with a 

 croupous membrane especially in the posterior part of the 

 small intestine and in the large bowel. The solitary follicles 

 and Peyer's plaques are swollen and may show ulceration. 

 The spleen is usually intact. 



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