114 EEPOET OF THE BUREAU OF ANIMAL ESTDUSTRY. 



The tissue is not diseased, as may be seen on microscopical examina- 

 tion. This condition is the result of a plugging of the bronchus sup- 

 plying the lobe with catarrhal products. The air can not enter the 

 tube, and all the tissue supplied by it remains collapsed. Groups of 

 lobules, permanently collapsed, may be found in other portions of the 

 lungs. 



A lobular broncho-pneumonia simulating infectious pneumonia 

 very closely is not infrequently found in young pigs. It seems to fol- 

 low collapse. 



Lung worms (Strongylus paradox us}* Are frequently found in 

 the fall and winter. They first appear in the extreme end of one of the 

 large bronchi, i. e., in the caudal tip of a principal lobe. Here they 

 may be detected as small, hard nodules, not larger than a small pea. 

 The lung tissue around them may be hypersemic, or perhaps in a state 

 of hepatization. The presence of the worms will in all cases explain 

 the lesions. 



More advanced changes are well illustrated by a case which came under our ob- 

 servation recently. Each principal lobe contained four masses about three-fourths 

 of an inch in diameter and very hard to the touch. The cut surface was coarsely 

 granular, the granules yellowish, imbedded in a pale red parenchyma, and probably 

 representing plugs in the smallest air tubes and alveoli. The trachea and bronchi 

 contained large quantities of gelatinous mucus. The bronchi leading to the hepa- 

 tized regions were completely occluded with lung worms. There was not pleuritis. 



In hog cholera the lung lesions are quite insignificant compared 

 with those of -other organs. In the acute type there is usually a 

 hemorrhagic condition. The entire surface is dotted with subpleural 

 blood extravasations. On section the lung tissue itself is found to 

 contain these hemorrhagic foci. Excepting the occlusion of a few 

 alveoli here and there with blood, there is no inflammation or hepa- 

 tization perceptible in any part of the lung tissue. 



In chronic cases of hog cholera these hemorrhages either never 

 take place or else they are speedily absorbed, for the lungs are, as a 

 rule, healthy, if we except the collapse of the small ventral lobes now 

 and then encountered as above described. 



When, in a case of swine plague, the sternum of a diseased ani- 

 mal is removed the ventral lobes which overlap the apex of the heart 

 only during a full inspiration do not collapse and drop out of sight 

 into the thorax, as in the normal lung, but they stand up over the 

 heart as two solid masses, of a deep red, mottled with yellowish points, 

 or more grayish, according to the stage of the disease. If these lobes 

 are normal the disease, as a rule, does not exist in the remainder 

 of the lung tissue. Frequently they are glued to the walls of the 

 thorax and the pericardium. 



The appearance of the lungs will thus lead to an easy diagnosis of 

 swine plague as distinguished from hog cholera. The intestinal 

 lesions which accompany swine plague in its most severe forms are 

 not so easily differentiated from lesions produced by hog cholera, but 

 a careful attention to descriptions given in the foregoing pages will 

 solve this difficulty in most cases. The disease of the large intestine 

 in swine plague is essentially exudative. Necrosis of the superficial 

 layer of the mucous membrane is secondary, the resulting ulcers 

 superficial. In hog cholera the lesions are at first either hemor- 

 rhagic or necrotic (ulcerative), or both. There is little or no exudate 

 preceding the stage of ulceration. 



* See p. 282 of the Report of the Bureau of Animal Industry for 1885. 



