348 DISEASES OF SWINE 



this method than by either of the others mentioned. In the intra- 

 venous injection every bit of the virus enters the blood-stream and 

 none is wasted. By the other methods it is always a matter of 

 doubt just how much will be absorbed, and this means that larger 

 doses must be given in order to insure favorable results. 



Figuring on the basis of 5 c.c. to the pound weight of the 

 animal, a 250-pound hog would receive 1250 c.c. 

 pints of virus blood, 

 same virus would be sufficient to kill a hog of this size that had 

 no immunity to cholera, we can get some idea of the powerful pro- 

 tection that is given by the simultaneous method of treatment. 

 An animal that three weeks before would have been killed within 

 ten days by the injection of ^ c.c. of virulent blood, now receives 

 two thousand times this dose of the same virus and shows no bad 

 results. This in itself is one of the most powerful arguments pos- 

 sible to offer in favor of the widespread use of the simultaneous 

 treatment. If this treatment will show such results as this at the 

 serum plants, it will show equally good results in the feed-lots of the 

 corn belt where hogs are produced in such large numbers. 



As a matter of actual experience, it is found in the serum-manu- 

 facturing plants that the hogs given these large doses of hog-cholera 

 virus for the purpose of hyperimmunization show little or no ill 

 effects from the treatment. There may be a slight droopiness for 

 an hour or so, and the animal may get a little sick at the stomach 

 and vomit immediately after being released from the crate, but 

 there is no sign of bad effects on the following morning, and a week 

 afterward, when the first tail-bleeding is made, the hog should show 

 a gain in weight of several pounds. 



Introducing the Needle. — The next and, in fact, the most diffi- 

 cult step in the operation of hyperimmunization is the introduc- 

 tion of the needle into the vein of the ear. The vein to be used is 

 selected, and the thumb and forefinger placed upon it near the base 

 of the ear. By compressing it gently at this point between these 

 fingers the flow of blood toward the heart is temporarily shut off 

 and the vein swells up along its course. This makes it more prom- 

 inent and increases the ease of inserting the needle. 



The needle should be detached from the rubber hose that leads 

 from the bottle containing the virus. It should be firmly grasped 



