98 DISEASES OF SWINE 



them were noticed to be off feed, and the entire herd was at once 

 loaded on the cars and shipped to one of the large packing centers. 

 Even then 3 were dead before they reached the market and 

 several others were condemned postmortem in the packing house. 



The following spring this same farmer purchased a dozen 

 brood sows at a pubhc sale and brought them home. These sows 

 were placed in a different feed yard, and gave birth to several strong 

 litters of pigs. These pigs and sows thrived in excellent manner 

 until about the first of June, when they were given the range of the 

 old feed lot. Within two weeks after they had been turned into 

 the cattle lot the pigs began to die, and within another two weeks 

 all the pigs but 4 were dead. The old sows also became sick, but 

 only 2 of them died, the balance passing through the attack. 

 . This case goes to illustrate two important principles in rela- 

 / tion to hog-cholera. One is that the virus of cholera is not entirely 

 destroyed by the freezing weather of the winter months, and espe- 

 cially not so when left protected by a thick layer of mud and refuse. 

 Under such conditions the virus will remain ahve, although it may 

 be less active than normally, and will attack new animals the fol- 

 lowing spring or summer. 



The fact that the old sows did not all die, and did not become 

 sick as quickly as the pigs, illustrates the fact that young animals 

 are more susceptible to cholera than the older animals. Not only 

 will young pigs more quickly take the disease, but the disease 

 is also more virulent in these young pigs, and the death-rate among 

 them is proportionately much higher than among the mothers. 



Another incident that I recall serves to illustrate the importance 

 of thoroughly cleaning and disinfecting pens after an outbreak of 

 cholera if you desire to make the pens habitable for hogs the fol- 

 lowing year: 



Two farmers, hving in close proximity of each other in central 

 Iowa, both had an outbreak of cholera on their farms during the 

 summer of 1909. In both cases the epidemic was very severe, and 

 wiped out the entire herd on each farm. 



After the hogs were all dead, one farmer thoroughly raked up 

 all the loose waste, cobs, old boards, Utter, etc., in his lots and 

 burned it. The pens and sheds were thoroughly sprinkled with 

 crude carbolic acid and chlorid of lime, and the inside of the hog 



