170 Inflaniniatiou of the Pleura. 



forced. In the further course of the disease the animals die quickly 

 after diarrhea has set in. An exact diagnosis can only be made on post- 

 mortem examination. 



In the beginning and often during its whole course, chronic 

 pleuritis does not lead to very prominent sj^nptoms, which be- 

 come marked especially during exercise. If there are extensive 

 adhesions, the vesicular breathing is less marked, but the percus- 

 sion sounds remain normal. In the presence of serous or more 

 purulent exudates in the thoracic cavity, after certain occur- 

 rences, for instance after hard work or after a cold, one ob- 

 serves acute exacerbations which, in addition to already exist- 

 ing areas of dullness and diminution or absence of breathing 

 sounds, lead to tenderness of the thoracic wall, marked dysp- 

 nea, dry, rough cough and moderate elevation of temperature. 

 Displacement of the heart by the exudate leads to change of the 

 apex beat and in the intensity of the different heart sounds in 

 various places of the cardiac region; disturbances of circula- 

 tion may also be present (stronger filling of the veins, presysto- 

 lic venous pulse, edematous infiltrations). (See compression of 

 the heart, Vol. I.) 



Disturbances of nutrition appear sooner or later. The 

 hair becomes lusterless and ruffled, the skin dry and less elastic; 

 emaciation gradually reaches a high degree, the production of 

 milk diminishes, the symptoms of cardiac weakness come on 

 and the animals die exhausted and emaciated. 



Course. Very mild cases of fibrinous pleurisy sometimes 

 run a very rapid course, occasionally one of a few hours only. 

 The symptoms may be of a very minor character, very insig- 

 nificant tenderness, soft friction sounds ; otherwise nothing ab- 

 normal can be detected in the chest. These symptoms may en- 

 tirely escape notice, as is proved l)y the well-known fact that 

 thickening of the pleura and adhesions are not infrequently 

 found in animals wdio have always been under observation and 

 who never showed symptoms of pleurisy. 



The fonnation of an abundant fluid exudate often requires 

 a long period of time; sometimes, however, the pleural cavity 

 may become filled within a few days to over one-half of its 

 space. The increase of the exudate usually occurs periodically 

 and is accompanied by elevation of temperature. Occasionally 

 the exudate only increases to such an extent that life is not en- 

 dangered for several months. 



Pleurisy with exudate may end in complete recovery, espe- 

 cially when the exudate is not very fibrinous or is purely 

 serous. In the majority of cases chronic tissue changes, such 

 as thickening and adhesions, remain as permanent residua. 

 Whenever the quantity of the exudate is considerable, its ab- 

 sorption requires several weeks and is interrupted by tem- 

 porary relapses. Adhesions which have been formed may sub- 



