PREFACE 



In writing this work it has been the object of the author to 

 prepare a book to meet the constantly increasing demand for a 

 volume that will give an intelligent interpretation of recent ad- 

 vances in the study of pathology of diseases of the hog, and the 

 apphcation of the newer therapeutic discoveries in their treat- 

 ment. 



No single branch of agricultural industry has made as rapid 

 advancement in the past twenty-five years as the swine-producing 

 business. It is only a short time ago that hogs were practically a 

 drug on the market. I can remember in the late 90's when fat 

 hogs sold for 3 cents a pound live weight in the Corn Belt States. 

 This same class of hogs to-day are worth from 9 to 11 cents a 

 pound. 



This enormous increase in the value of hogs from a financial 

 standpoint has given a marked stimulus to the swine-producing 

 industry, and has developed a desire on the part of hog owners 

 to give their sick hogs the very best possible attention, as the 

 death of one of these animals means a large financial loss. The 

 veterinarian has also been called upon more frequently to treat 

 sick hogs, and this part of his practice is becoming a considerable 

 item in the business of every practising veterinarian. 



The development of hog-cholera serum as a means for man- 

 agement of hog-cholera has given an added stimulus in the past 

 ten years to the demand for scientific treatment of sick hogs. 

 Both veterinarian and farmer have been quick to realize the im- 

 portance of this new means of treatment, and there is a wide- 

 spread demand for complete explanation of the underlying scien- 

 tific basis for this means of combating the disease. 



In this work it has been my especial aim to explain the prin- 

 ciples of manufacture and use of hog-cholera serum in such a 



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