310 



SWINE PRACTICE 



disease may prevail in swine that are kept in clean sanitary quar- 

 ters. Pood seems to have little, if any, influence upon the ]irevalence 

 of the disease, although insufficient or poor quality of feed would no 

 doubt predispose to this disease, the same as to any other diseased 

 condition. 



Etiology. — The specific cause of infectious necrotic enteritis has 

 not been identified. This condition is not the result of the filtrable 

 virus that produces hog cholera, for it has been demonstrated by the 

 injection of filtered blood from uncomplicated cases of infectious 

 necrotic enteritis into swine that were susceptible to hog cholera that 

 the filtrable virus does not exist, at least in sufficient quantities or of 

 sufficient virulence to produce disease. By experiment it has been 

 demonstrated, although the findings are not positively conclusive, 

 that the B. necrophorus is not the primary cause of this condition. 

 Likewise, it has been rather conclusively demonstrated tiiat the B. bi- 



•>vt 



Fig. 91. Group of pigs affected with necrotic enteritis. These animals 

 were maintained in pens that were as insanitary as could possibly bo 

 imagined. Note the general unthrifty appearance. 



polaris suis is only a secondary invader in infectious necrotic enter- 

 itis. By a microscopic examination of the lesions in the intestine it 

 is possible to demonstrate the B. necrophorus in an occasional case 

 of this disease, the B. bipolaris suis in over 50 per cent of the cases, 

 the B. coli communis in practically all cases, the B. paratyphoid A ifc 

 B in a few cases, and perhaps a variety of other microbian agents 

 in various cases, but the principal incriminating evidence at this 

 time is in support of the B. suipestifer as the principal or causative 

 factor of infectious necrotic enteritis in swine. The B. suipestifer has 

 been described as occurring normally in the intestine of healthy 

 swine, but recent investigations by Jordan and Ten Broeck indi- 

 cate that this organism does not normally inhabit the intestine of 

 swine and when found in normal animals its occurrence is looked 

 upon as an indication of a carrier. The B. suipestifer occurs regu- 

 larly in the intestinal lesion and in other tissue of affected animals, 

 and it is possible that the final proof of its causal relation to infe'^- 



