404 DISEASES OF SWINE 



of above 104° F., and which, accordingly, are not showing any signs 

 that they have yet been attacked by the germs of cholera, there are 

 two methods of treatment remaining open. One method is to give 

 them serum alone, which will certainly protect them from the dan- 

 ger at this time, and if they become the object of attack by the 

 cholera germs which are present in the feed lot they will also 

 develop the power of producing the germ-fighting bodies which 

 give a permanent protection against the disease. 



Of course, there must always be some question in the cases 

 that are handled in this manner as to whether they will take up 

 enough of this hog-cholera virus from the feed lot to educate their 

 cells to the need for producing germ-fighting bodies as a standing 

 army to ensure freedon from further attacks. This is the all- 

 important point in the development of immunity. A standing 

 army of antibodies is just as important, as a guarantee against 

 an attack by disease, as a standing army of trained soldiers is to 

 the nation as a guarantee of peace with other nations which might 

 be incUned to attack us were we not so protected. Tfie resem- 

 blance is very close in the two instances. We have learned, as a 

 result of our experience in wars with other countries, that it is ab- 

 solutely necessary, if we are to be free from warfare, that we have 

 a good supply of trained soldiers ready at a moment's notice to de- 

 fend us from attack. A nation that has never been through a war 

 cannot appreciate the need for such a body of trained fighters. It 

 is just so with the body of the hog. It learns only by actual ex- 

 perience from an attack of the hog-cholera virus the need that it 

 has for a trained army of fighters who will be able to prevent any 

 second attack from the same source. As soon as it has met one 

 attack of this kind, it never forgets the lesson learned, and in future 

 keeps a well-trained guard always on hand. 



In order to make certain that there will be such an attack, and 

 the development of a permanent immunity in these animals which 

 at the time of treatment are not affected with a high temperature 

 or other evidences of cholera, it is a much better plan to give an 

 injection not only of serum, but also of hog-cholera virus. In this 

 manner we cannot possibly do any harm, and we make certain that 

 the animal will develop a permanent immunity. 



