INCUBATION PERIOD OF CHOLERA 159 



If they have been exposed to cholera before you bought them, the 

 disease will make its appearance before the end of thirty days. If 

 this farmer had only done this he would not have had cholera in 

 his old herd at all. The animals which he bought would have been 

 the only ones he would have lost. While this in itself would have 

 been a big loss, it would have been a small one compared with what 

 he actually did lose when he lost not only the newly purchased 

 animals, but nearly all of his old herd as well. 



Make it an invariable rule to keep new hogs in separate pens 

 for at least three weeks, and it is better to keep them away from 

 your regular herd for four weeks. 



Removal of Sick from Herd. — It has often been said that 

 by removal of the sick hogs from a herd and keeping them sepa- 

 rate we will be able to check the spread of cholera in the herd. 

 While this is a good practice, and may occasionally be a success, it 

 is by no means always so. As a rule, the entire herd has already 

 been infected from the manure and other discharges of the sick 

 animals, and it is only a question of a few days when they will come 

 down with the disease. As a matter of fact, the urine and manure 

 of a cholera hog are capable of causing the disease in a healthy hog 

 for several hours before he shows signs of being sick. 



Separation Into Small Herds. — About the only way in which 

 separation of well from sick animals can do much good is to remove 

 the entire herd to a new range or pasture, and then divide them up 

 into small bunches of, say, 3 or 4 animals. In this way we may 

 be fortunate enough to in part check the disease. A few of the small 

 bunches may entirely escape and be saved, whereas, if they had 

 all been left together, they would have taken the disease along 

 with the rest of the herd. Once in a while, by leaving the sick hogs 

 in the old feed lot and turning all the well animals into a new 

 pasture which has not had hogs on it for several months, the dis- 

 ease may be checked. As a rule, however, it is very hard to head 

 the disease off once it makes its appearance, except by the use of the 

 new treatment by means of serum. 



This case also gives us another very interesting point about the 

 incubation period of cholera. It will be noted that the cholera 

 showed up first in the shoats, and a few days later the old sows 

 began to get sick. This is usually always the case, as the younger 



