FOURTEENTH ANNUAL YEAR BOOK— PART VI. 527 



comparatively large dose of serum. When you have had an infected 

 herd treated, some of the animals were sick and some were not. Unless 

 the temperature of every animal was taken, the man treating your herd 

 did not know how many of them were sick. A hog just coming down 

 should receive an increased dose if you want to get good results. If you 

 find a hog that shows a temperature, increase the dose by half, or even 

 double it, and you will find that the hog will get along and will get 

 well. If you give a hog a sufficient dose of serum, he will not get sick; 

 if you give him not quite enough, he will get a little bit droopy and 

 show quite a high tema^erature under the thermometer, but get on 

 and get well; if the dose is too small, he will probably get just as sick 

 as if he hadn't had the serum, and .die. You know when you are going 

 up a hill in an automobile and don't have your gasoline supply just 

 right, you are going to kill your engine before you get over the top. It 

 is the same way with the dose of serum for a hog. We can't measure 

 exactly how much susceptibility your hog has or just how much po- 

 tency there is in the serum; the only way to test the serum is to give 

 it to healthy shoates; if it protects in moderate doses, it is good serum; 

 if it fails to protect, we say it is not good serum. I think in more 

 than half of the cases where bad results have been obtained from the 

 use of serum, the dose has been too small. I don't doubt that some 

 rival concerns have sent out serum that is low in potency, but a good 

 many times the fault has been with the administration; a sufficient dose 

 has not been given, nor the temperature of each hog taken. 



Q. Can you tell about what age pigs should be treated with 

 double treatment to be immune afterwards? 



Dr. Niles : If you treat very young pigs with double dose, a 

 few of them will lose their immunity; if you treat them about 

 eight or nine weeks of age, very few of them will lose it. 



Q. How long will the serum keep? 



Dr. Niles: "We don't believe in keeping it more than a few 

 days. It keeps well if you keep it cool. "We have kept serum 

 two or three years, and had it retain its strength, but we don't 

 like to retain it over a week. 



Q. I would like to know whether hogs should be thin in flesh 

 or fat. 



Dr. Niles: We have always considered that the hog excessively 

 fat is more susceptible to hog cholera than the leaner animal; 

 that is, they will die in greater numbers if disease attacks the 

 herd. Consequently, we find that the pure-bred swine that have 

 been fed high will contract the disease more acutely, and a larger 

 per cent of them die if there is nothing done to them, than the 

 ordinary farm herd, and we always give them more serum than 

 the ordinary animal. 



