62 DISEASES OF THE PLEURA 



Hemorrhagic pleuritis is generally the result of infectious 

 diseases and malignant growths on the pleura. The exudate 

 is chiefly serous, with red blood cells present, but at times 

 may be almost pure blood. 



Purulent pleuritis (pleuritis purulenta; pyothorax; em- 

 pyema) is the result of infection by some one of the many 

 pyogenic organisms (staphylococcus, etc.). It may begin 

 as a purulent pleuritis or it may follow infection of the sero- 

 fibrinous form. In the pleural cavity is found a varying 

 amount of cloudy fluid which contains a great number of pus 

 cells. It may be greenish in color at times, but is usually 

 yellowish. The pleurae are generally thickened and con- 

 gested and covered with flakes of fibrin or degenerated 

 endothelium. The pus may be completely absorbed and the 

 two surfaces unite with dense adhesions; or it may become 

 caseated and undergo calcareous infiltration. The changes 

 are most marked in the visceral pleura, which becomes 

 greatly thickened, at first being soft and edematous while 

 fluid is present, but as .this disappears it becomes indurated. 

 During the course of purulent pleuritis there is always more 

 or less involvement of the lungs which in some cases may 

 result in pleurogenic pneumonia. In some chronic cases of 

 pleuritis (pleuritis granulosa) there are numerous papilloma- 

 like enlargements distributed over the surface of the pleura, 

 and these by becoming confluent may produce extensive 

 masses which interfere with the function of the neighboring 

 tissues and organs. 



The serous exudate contains endothelial cells, white cor- 

 puscles and small particles of fibrin. The infected exudate 

 contains numerous pus cells, endothelial cells, and various 

 kinds of detritis. A rather high percentage of albumin is 

 found in the serous exudate. 



Symptoms. In the early stages of pleuritis the symptoms 

 manifest themselves in various ways, depending largely 

 whether the disease is primary or secondary, local or general. 

 In acute, primary pleuritis the disease usually begins abruptly 

 with pronounced general symptoms, viz: A chill, the animal 

 seeking a warm place, twitching and trembling of the muscles, 

 followed in a few hours with an elevation of temperature 



