568 IOWA DEPARTMENT OF AGRICULTURE 



The amount taken at a bleeding varies as some hogs would stand the 

 loss of blood better than others. We aim to extract five cubic centi- 

 meters per body weight at each tail drawing, though in one case we 

 took as high as ten cubic centimeters, and have experienced difficulty 

 in drawing five cubic centimeters per body weight in others. The hogs 

 that are being bled for serum should receive nourishing food and good 

 shelter. The blood as it is drawn into sterile jars is defibrinated by 

 shaking or stirring with a sterile glass rod and one-half of one per cent 

 phenol added as a preservative. The serum from each hog is kept sep- 

 arate in a large bottle until the hog is killed, and each drawing is labeled 

 on the bottle with date the drawing was made.. This is done to avoid 

 mixing any serum from hogs that upon post morten show lesions of any 

 disease, such as tuberculosis. 



Crates are also used in bleeding hyperimmunes as well as in producing 

 hyperimmunity at the Iowa State Laboratory; for the latter we have de- 

 scribed the crate; for the former, the crate is of simple type, differing in 

 no way from, an ordinary hog crate. After securing the hyperimmune in 

 the crate, the end gate is removed and the hog retained in the crate by 

 suspending his hind quarters in a sling, thus preventing the hog from 

 backing out of the crate. A cloth is placed over the crate with a small 

 hole through which the tail is placed making conditions as sanitary as 

 possible. 



THE TESTING OF SERUM. 



All serum before it is bottled for shipping is tested to determine its 

 potency, waiting until we get the entire bleeding of five or six hogs, and 

 mixing it in a five gallon sterile container. Approximately speaking, we 

 test the serum in one thousand dose lots. From this mixture, we treat 

 six shoats weighing one hundred pounds each, three receiving twenty 

 cubic centimeters, and the other three receiving fifteen cubic centimeters 

 of the mixed serum, and at the same time in the opposite thigh, two 

 cubic centimeters of virulent blood is introduced; also using the same 

 virulent blood on two shoats without the preventive serum to test the 

 virulency of the cholera blood. If the latter, or check, as they are often 

 called, succumb to the disease, and those with the preventive serum live, 

 we are justified in considering the serum potent, and if used under proper 

 conditions in outbreaks of hog cholera, will aid in checking the spread 

 of the disease. It, however, should never be. used jmJiogs showing symp- 

 toms, as it is then too late, for it possesses no curative properties to speak 

 of in limited doses, and therefore should be confined to hogs that have 

 recently been exposed but which show no symptoms. 



BOTTLING. 



After waiting about twenty days, if our test hogs are healthy and ap- 

 petite good, and the check hogs are dead, we bottle the serum. 



