CHAPTER XVIII 



SWINE FEVER 



Swine fever is a specific contagious and infectious disease 

 aif ecting pigs of all ages, and having a world-wide distribu- 

 tion. It is primarily caused by an ultra-visible virus, and 

 characterized by inflammatory and necrotic lesions due to 

 secondary invasions. 



This disease, in common with several other diseases 

 where secondary bacterial invasions play an important part, 

 was, up to the year 1904, thought to be due to a bacillus, 

 whereas in point of fact the bacterium then isolated has 

 now been proved to belong to the secondary group. 



In that year Dorset and his co-workers, by injecting 

 the blood-filtrate taken from a diseased pig into a healthy 

 animal produced the disease, and settled once and for 

 all the fact that swine fever is caused by an ultra- 

 microscopic virus. 



Symptoms. — These are by no means constant, nor are 

 their interpretations always accurate, the former largely 

 depending upon which causative factor predominates. 



Where intestinal lesions are the most pronounced, 

 abdominal symptoms will predominate. Where the pul- 

 monary organs are most severely affected, thoracic symp- 

 toms will be evident, and where both systems are involved, 

 a complexity of symptoms will be seen. 



In the septicemic form the disease usually runs a very 

 rapid and equally fatal course. In this condition the 

 animal isolates itself, refuses food, and lies down con- 

 stantly. The bowels at first are constipated, but this soon 



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