92 DISEASES OF SWINE 



Caution Necessary i>i Use of Virus Blood. — This is a point 

 which must be especially remembered in the administration of 

 the serum-simultaneous, or serum and virus treatment for cholera. 

 The virus blood which is injected with the serum is taken from the 

 vessels of an animal which is suffering from acute cholera, and a 

 few drops of it is sufficient to produce the disease in other animals 

 in a few days, unless they be properly protected by a dose of serum. 

 Great care must be exercised in the handling of this virulent blood, 

 and any of it which is left over at the end of the vaccination 

 should be immediately burned, to prevent any possible danger of 

 it being scattered about in some place where it might be carried 

 in any manner to other hogs which had not been protected by the 

 use of serum. 



All Body Discharges are Dangerous. — When a case of cholera is 

 fully developed every one of the body discharges teem with the 

 virus of the disease. The saliva of diseased animals carries large 

 quantities of the virulent material, and food contaminated with 

 the sahva of a sick hog is capable of transmitting the disease to 

 healthy hogs. In like manner, watering-troughs may become con- 

 taminated by sick animals drinking from them. 



The discharges from the eyes, which are described under the 

 head of Symptoms of Hog-cholera, are also infectious and capable 

 of transmitting the disease. Milk from sows suffering with cholera 

 is also laden with the ultramicroscopic organism, and is capable of 

 transmitting the disease to the pigs. However, pigs are so sus- 

 ceptible to hog-cholera that they are usually infected before the 

 mothers from other sources, and, accordingly, are rarely made sick 

 through the milk. 



Summary. — In summing up the direct causes of hog-cholera 

 we have the following points to remember: 



(1) The disease is not due to the hog-cholera bacillus which 

 was at one time described as the cause of the epidemics which 

 devastated the herds in our hog belt every year. 



This organism is, however, usually present in the sick animals, 

 being especially found in the ulcers in the large and small in- 

 testines and in the feces. 



(2) The actual cause of hog-cholera is a very minute organism, 

 which is so small that it passes through the finest of filters, and 



