Anatomical Changes. 



273 



21 days after the infection large sections of the intestinal mucous membrane may- 

 be coyered with a deposit or exudate, and the intestinal wall may be 3 to 4 mm. 

 m thickness. The- mucous membrane of the cecum however may show necrotic 

 areas as large as a quarter in size. 



According to Marek's histological examinations the nature of the changes 

 m the intestinal mucous membrane are those of a croupous, or croupous-diphtheritic 

 character. The epithelial layer and the propria mucosae changes through a coagu- 

 lation necrosis, into a homogenous layer, which contains fibrinous threads and 

 obstructed blood vessels. This layer is surrounded by a wall of polynuclear leuco- 

 cytes. The bacillus suipestifer and the Bac. necrophorus are found in great 

 numbers on the border line between the necrotic and healthy tissue. The patho- 



Fig. 52. Hog Cholera. Pig affected for two weeks. 



logical process frequently commences in the follicles, occasionally however the 

 necrotj". layers may contain healthy follicles. If larger bacterial colonies develop 

 in otl.'.r organs they may cause coagulation necrosis in such places, which later 

 result ; in the formation of sequesters. 



3. Pectoral Form. This form is characterized by an acute, 

 usually croupous, more rarely catarrhal pneumonia, which in the 

 later stages passes into multiple necrosis. Frequently there is 

 also a fibrinous or sero-fibrinous pleurisy and in some instances 

 also a similar pericarditis. Besides this, the mucous membrane 

 of the gastro-intestinal tract reveals a diffuse, acute inflamma- 

 tion, while in acute eases the other organs indicate a general 

 septic infection. Otherwise the autopsy findings are identical 

 with those of swine plague (see p. 130), and the disease can 

 only be distinguished from this by the fact that the filtered blood 

 or material from the organs is virulent (see diagnosis). 



4. Mixed Form. The great majority of cases which are 

 found in infected herds belong to this class. The lesions of the 

 intestinal and pectoral forms, with the corresponding changes 

 of the organs, are present simultaneously from case to case 

 but in varying intensity; therefore the autopsy findings vary 

 greatly, even in the animals of one and the same herd. In 



