298 Missouri Agricultural Report. 



tion, and death may occur without any marked visible changes in 

 the various organs of some of the affected animals. The presence 

 of intestinal worms in a case of this kind has more than once mis- 

 led farmers and veterinarians to an incorrect diagnosis. 



The opinion has prevailed for many years that two wide-spread 

 infectious diseases exist among the swine of the country. One 

 called "hog cholera," affecting principally the intestinal tract, 

 showing typhoid symptoms, and ulcerations; the other called 

 "swine plague," and marked by a more or less extensive conges- 

 tion or inflammation of the lungs. While it has not yet been defi- 

 nitely proven, the indications are strong that we have but one 

 disease; and that the differences which have led to the two names 

 are simply complications of the one infectious malady. In a some- 

 what large experience I have always found both the intestinal and 

 the lung complications in different animals of the same herd, and 

 often in one and the same animal. In experimental cases, hogs 

 that have been immunized against "cholera" by the new "hog- 

 cholera-serum" do not contract "swine-plague" when exposed to 

 hogs suffering from that type of the disease. Moreover, the inocu- 

 lation of healthy pigs with infectious blood from an animal suf- 

 fering from one type, may produce the other type of the disease. 

 I am confident, therefore, that for all practical purposes it will be 

 wise to quit using the term "swine plague," and apply the popular 

 name "hog cholera" to every outbreak of an infectious swine dis- 

 ease, in which large numbers of hogs die; for it is probable that 

 the true infectious agent in every outbreak of an infectious swine 

 disease in this country is the "filterable virus" of hog cholera, the 

 existence of which was demonstrated by Dr. Dorset and associates. 

 It is, however, probably true that the ulcerations of the intestines, 

 and their typhoid condition is partly due to the associated action of 

 the ordinary colon bacillus, or to the bacillus described by Salmon 

 and Smith as the hog cholera organism; and, that the "pneumonic 

 complications" are partly due to the associated action of what has 

 been called the "swine plague bacillus." With the evidence avail- 

 able, we must, however, regard these associated bacteria as harm- 

 less under ordinary conditions. They probably invade the tissues 

 of the body only after the "true virus" of cholera has prepared 

 the way. 



What has been said is probably sufficient to enable you to rec- 

 ognize the presence of cholera in your herds. 



