332 ACUTE GENERAL INFECTIOUS DISEASES 



swine with the filtered blood of the suspect. Hog cholera may 

 be confused with: 



(a) Swill Cholera. — In districts free from hog cholera a 

 disease appears very like cholera. It is due to feeding swill 

 containing dishwater in which is a quantity of powdered soap. 

 Even the postmortem lesions resemble those of cholera. 

 Careful inquiry into the mode of feeding usually suffices to 

 explain the origin of the disease which promptly disappears 

 when the food is changed. Hog cholera, however, commonly 

 breaks out among swine fed kitchen offal from large institu- 

 tions (penitentiaries, asylums). The food in these cases is 

 not the cause. Large numbers of hogs are bought up indis- 

 criminately to consume this waste, and with them a few 

 which either have cholera in a chronic form or are cholera 

 convalescents ("germ carriers"). 



(b) Tuberculosis. — This is a common disease of swine which 

 follow tubercular cattle, are fed skim milk containing tubercle 

 bacilli, or the tubercular offal from slaughter houses. It would 

 be confused only with chronic cholera. The history and ne- 

 cropsy nearly always suffice to differentiate between the two 

 diseases. In cases of doubt the bacteriological examination 

 (staining for tubercle bacilli) may be employed. 



(c) Lung-worvis (Strongylus Paradoxus). — These thread- 

 worms are sometimes found in the bronchi of young pigs; 

 They induce chronic cough and general unthriftiness. Occa- 

 sionally death is induced through pulmonary edema. A 

 necropsy reveals absence of cholera lesions and the presence of 

 the strongylus in the foamy mucus of the small bronchi. 



Prognosis. — The prognosis varies with the outbreak. In 

 some years the disease assumes a mild form leading to a 

 mortality of not over 16 to 20 per cent. ; in others it may reach 

 80 to 100 per cent. The septicemic form is nearly always 

 fatal. The pectoral type leads to the death of all swine 

 showing marked pulmonary symptoms (dyspnea, cyanosis, 

 etc.). While recoveries in the intestinal form are not un- 

 common, convalescence is often prolonged which greatly 

 affects the value of the hog. The same is true of chronic 

 cases which seldom regain their former thrifty condition. 

 An exception is formed in old breeding boars and sows. 



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