Cholera Suis, Hog Cholera, etc. 31 



prove as deadly as outbreaks of genuine hog cholera, and are 

 habitually mistaken for them. They do not, however, as a rule 

 extend beyond the particular herd which has been exposed to the 

 fault}' management, and introduce no risk of a general spreading 

 infection. The careless owner suffers and adjacent herds escape, 

 unless exposed to similar causes. But if the hog cholera germ is 

 present these pave the way for its destructive advance and tend to 

 enhance the mortality. It may even be that the combination of 

 the two factors is a condition of the eruption of a severe attack. 

 The faulty feeding or food or poison by itself could be resisted, 

 and the comparatively non-virulent hog cholera bacillus might 

 have been resisted, but with the weakened system and digestive 

 apparatus, the microbe finds a specially inviting field in which it 

 can multiply destructively , and where it can gather a virulence 

 which will enable it to invade and sweep away herd after herd in 

 a deadly epizootic. 



I may add, as a prominent factor in the great modern exten- 

 sions of hog cholera, the habitual aggregation of swine in large 

 herds. This with the rapid steam transit of modern times, and 

 the great aggregations of hogs in one common market, probably 

 contributes more than anything else to the extraordinary diffusion 

 of the infection. Hy accident, purchase or otherwise, a large 

 herd becomes infected, and the owner, knowing that delay is 

 ruin, at once ships the apparently healthy animals to market ; 

 these infect anything they or their excretions come in contact 

 with ; if sold in smaller lots they carry infection into every 

 locality where they go, and along the route ; if sold for slaughter, 

 they still diffuse infection through the herds that receive their 

 butcher and kitchen trimmings. 



Finally other domestic animals may bring in an infection which 

 becomes manifested by symptoms similar to those of hog cholera, 

 and which if really different, yet serves to pave the way for such 

 an outbreak. Galtier's remarkable experience with a pneumo- 

 enteritis in sheep, introduced into five separate flocks by infected 

 pigs from the same market, is significant in this respect. It is 

 further significant that the hog cholera bacillus is a very protean 

 microbe. Th. Smith, to whom we owe more than to any one 

 else the identification of the germ, gives seven varieties, which 

 showed well-marked distinctions in their morphology, in their 



