Swine Plague. 491 



Hakes of coagulated fibrin. If a large amount of effusion of fiviid has 

 occurred adhesions may be prevented until its absorption has 

 occurred. If the inflammatory process does not subside^ or is of 

 great intensity from its commencement, pus may be formed, and 

 adhesions, along with a purulent exudation, may be encountered. 



Lungs. — The pneumonia maybe of the croupous or catarrhal type. 



Croupous Pneumonia. — This is an inflammation of the parenchyma 

 (cellular substance) of the lung. The poison reaches the lung from the 

 blood, and a considerable area of the organ may be involved. The 

 inflammation of the lung may be accompanied by inflammation of the 

 pleura over the inflamed area, and there may be sub-pleural htemorrhagic 

 spots. Sometimes the inflammation extends to the pericardium and 

 peritoneum. The morbid process in the lungs passes through three 

 stages, and the various stages may be observed in slaughtered 

 animals. 



In the first stage (stage of engorgement) the lung becomes 

 exceedingly vascular. It is loaded with blood and has a dark red 

 colour. Its weight is somewhat increased, and its elasticity dim- 

 inished. It is friable^ and pits on pressure. From its cut surface, 

 when pressed, there exudes a reddish frothy fiuid. 



In the second stage (red hepatization) the lung is decidedly 

 heavier and its bulk is increased. The pleura over the inflamed area 

 may be covered with lymph and the dark purple colour of the lung 

 beneath is visible through it. In consequence of the air spaces being 

 blocked up by the inflammatory products, the diseased lung sinks in 

 water. It ,is exceedingly friable and readily breaks down. The cut 

 surface has a granular appearance from coagulated inflammatory 

 material which tills the air cells, projecting from them. The colour 

 of the cut surface is dark reddish brown, and may be intermixed with 

 grey, giving a marbled appearance to the sections. 



In the third stage {'gvej hepatization) the weight, density, and 

 friability of the lung are further increased. The lung is soft and 

 pulpy, and from the cut surface a puriform fluid (pus) exudes. The 

 colour is dirty grey or yellowish white, or gradations from reddish 

 brown to grey may be observed. A mottled appearance may thus be 

 presented in passing from the red to the grey stage. The bronchial 

 tubes of the afl^ected area are always inflamed and contain sticky, 

 bloodstained mucus. Croupous pneumonia may terminate by resolu- 

 tion, or may go on to the formation of abscess. The bronchial and 

 mediastinal glands are found inflamed and swollen. 



Catarrhal Pneumonia. — The lung tissue exhibits solid, non-crepi- 

 tant patches, due to inflammatory consolidation. The pleura over the 

 -affected area may not be altered in character, and the diseased portion 

 viewed through it has a bluish colour. On section it is, in the early 

 stages, dark red, smooth and shiny, then the colour passes through 

 greyish red to greyish yellow, and a greyish juice can be expressed 

 from it. 



