186 SWINE DISEASES 



bone marrow the evidence is in favor of the existence of 

 cholera. 



Swine plague is distinguished from the pectoral form 

 of cholera by the fact that the former is characterized by 

 catarrhal pneumonia in the early stages of the disease, 

 and by necrotic pneumonia in the later stages, and also 

 by the presence of fibrinous pleurisy with or without 

 adhesions. 



Petechial hemorrhages of the kidney were formerly 



(considered pathognomonic of cholera, but these hemor- 



/ rhages have been found in the kidney rather frequently 



> when cholera was absent, or at least the blood from such 



J cases failed to produce cholera in healthy, susceptible 



* Pigs- 



Engorgement of the spleen is a common lesion in 

 acute cholera, but this condition sometimes occurs as a 

 result of disturbed digestion and as a result of leukemia, 

 and is a common lesion of other septicemic diseases. 

 Therefore enlarged spleen alone should not be considered 

 a sufficient evidence upon which to base a diagnosis of 

 cholera. 



The congestion and hemorrhage of the lymph nodes 

 is one of the most common and characteristic lesions of 

 cholera, but this lesion is not always present. Hemor- 

 rhages of the subserosa and submucosa are quite constant 

 in cholera; however, they may occur in any other septi- 

 cemia. The changes of the bone marrow, although oc- 

 curring to a less degree in other septic conditions, are 

 among the most characteristic lesions of cholera, but this 

 lesion is absent in some of the peracute cases. Petechial 

 hemorrhages are also of common occurrence in swine 

 erysipelas, but this disease can be differentiated from 

 cholera by the demonstration of the organism of swine 

 erysipelas in the blood or splenic pulp. 



The principal diagnostic lesions of cholera are sub- 

 serous and submucous hemorrhages, congestion and 

 hemorrhages of the lymph nodes, and the discoloration of 

 the bone marrow. Next, in order of frequency, is croup- 

 ous pneumonia of the cardiac lobe of the lung. 



/ 



