140 DISEASES OF SWINE 



reddened condition of the skin and visible mucous 

 membranes is very noticeable. 



In most outbreaks of swine plague, a smaller 

 .per cent, of the herd becomes affected than in hog 

 cholera. Recovery seldom occurs. The disease 

 frequently takes on the chronic form. 



Lesions.— The lung and pleural lesions predom- 

 inate. The inflammation of the lungs is limited 

 to certain lobules, unless it is in the very acute 

 cases. The lining membrane of the bronchial 

 tubes is inflamed and the smaller tubules are 

 filled with inflammatory exudates. Not over one- 

 fourth of the lung tissue may be diseased. All 

 stages of pneumonia may be present. On cutting 

 across the lung, the section usually appears mot- 

 tled with grayish red and reddish yellow areas. 



Inflammation of the pleura is a very constant 

 lesion. The membrane covering the lungs may 

 be reddened, thickened and adherent to the chest 

 walls. Other parts may present the same appear- 

 ance. False membranes sometimes form and give 

 the pleura a roughened appearance. In some 

 cases it is greatly changed. The sack surrounding 

 the heart (pericardium) is diseased in very much 

 the same wa:y as the pleural membrane. 



The mucous membrane of the stomach and in- 

 testines is reddened, congested and inflamed in the 

 majority of hogs that die of swine plague. In 

 some cases ulceration occurs. The ulcers differ 

 somewhat from the hog cholera ulcers in that they 



