Swine Growers' Session. 117 



munity is of a passing nature; and that for the production of a 

 permanent immunity the animal must be infected either from ex- 

 posure to the disease or by actual inoculation with the virus. If 

 this is done at the time the protective serums are present, no severe 

 results follow, and the animal acquires an immunity which is quite 

 permanent. In practical work in the field I hardly think that it is 

 necessary, where animals are already exposed to the disease, to 

 resort to the inoculation of the virulent blood. In the cases we 

 have already mentioned on the State farm, we did not think it 

 necessary to inject the virulent blood on account of the probability 

 of the animals becoming infected through natural means. Dr. 

 Niles, writing me on December 14th, says in regard to this matter 

 — "The results of our field work have been most encouraging, and 

 we are satisfied that serum used alone in herds in which disease 

 is just starting, will save a very large majority of the animals." 



We must not overlook the importance of the ordinary sani- 

 tary measures in the prevention of this disease, for in the history 

 of plagues of all kinds more has been done by good sanitation than 

 by vaccination. In small-pox, diptheria, bubonic plague, and other 

 infections, Boards of Health do not relax in the least the enforce- 

 ment of quarantine and disinfecting measures, although there are 

 vaccines against some of these human maladies; and if the farm- 

 ers would apply the proper sanitary measures in the handling of 

 hog diseases the losses would not be so great. For instance, the 

 good effect of quarantine will be illustrated by the experience of 

 one of the members of this Association, whom you all know. I 

 refer to Mr. Gentry, who tells me that he has a number of times 

 prevented great losses of hogs in his herd by placing in temporary 

 quarantine those that he had shown at the various State fairs. It 

 became his custom, after a sad experience or two with hog cholera, 

 to put the "show herd" apart from the general herd for a few 

 weeks after their return to the farm, and to put these in charge of 

 an attendant who did not come in contact with the other hogs. 

 He has brought the disease on to his farm a number of times, but 

 has succeeded by strict quarantine measures, and thorough disin- 

 fection, in preventing its spread to the other hogs on his farm. 



The free use of disinfectants like carbolic acid and quick lime 

 are very important in the prevention of this disease, and in stamp- 

 ing it out, when it once invades a farm. Thoroughness of disin- 

 fection is the important thing. A slight sprinkling of lime here 

 and there does not suffice; you must make the yards look as if a 

 snow had fallen. One of the members of this Association, Mr. 



