54 EQUINE PLEURO PNEUMONIA 



Stated furnishes the largest number of subjects for post-mortem 

 examination, there are many hemorrhagic foci, possibly gan- 

 grenous pneumonia with secondary pleuritis. Parenchymatous 

 degeneration of other vital organs is reported. Areas of the 

 lung tissue of greater or less size are thickened and hepatized- 

 These are located more especially near the base of the lungs 

 and in the lower (ventral) portions. Bright foci which are 

 distinctly defined from the neighboring tissues are scattered 

 through the hepatized areas and appear on the surface of sec- 

 tions of the hepatized parts. Uusually several of these foci 

 are present. They vary in size from a millimeter to 20 or 

 more centimeters in diameter. In recent lesions, these areas 

 are very small, of a grayish-red color and surrounded by a 

 grayish zone consisting of leucocytes. In more advanced 

 lesions they become yellowish, necrotic and finally cavities 

 are formed varying from the size of a pea to that of a hen's 

 egg. These cavities are surrounded by a smooth capsule. 

 There are other foci which contain greasy, fetid, watery pus 

 (gangrene of the lungs), by reason of the necrotic part of the 

 lung undergoing liquefaction in consequence, it is stated, of 

 the admittance of air. The lungs often contain suppurating 

 foci composed of a whitish pus mixed with necrotic lung 

 tissue. It sometimes happens that the foci just described are 

 absent in the lungs, although during life distinct symptoms 

 of such a localized affection may have been present. In these 

 cases, it is assumed that absorption of the necrotic tissue has 

 taken place. The remaining tissue of the lungs is more or 

 less hyperemic or edematous. 



The pleurae show signs of a diffuse, exudative inflamma- 

 tion, the starting point of which in the large majority of cases 

 is from necrotic deposits which are situated in the periphery 

 of the lungs. Pleuritis may occur, however, apparently as a 

 primary lesion without the necrotic foci being present. The 

 contents of a necrotic deposit in the lungs rarely break 

 through into the pleural cavity. In some cases, the visceral 

 and costal layers of the pleurae are congested, diffusely or in 

 spots, and are sprinkled with hemorrhages. Frequently the 



