DISMASMS OF THE HESPISATOXY OSGAS^. 29 



Chronic pleurisy occasionally follows the acute form of the disease, but 

 in tlie majority of cases is a sub-acute affection from the first. It is often 

 developed imperceptibly, those prominent symptoms observed in the 

 acute form, being absent or lacking sufficient intensity to characterize 

 the disease. 



Anatomically, the conditions existing in chronic pleurisy are essentially 

 the same as in the acute form. The pleural cavity contains a liquid effu- 

 sion of serum and lympli , which in the event of recovery becomes 

 absorbed. Bands of adhesion are formed uniting the inner surface of the 

 pleura, and the chest walls become contracted, leaving a depression gen- 

 erally permanent, more especially In cases of large effusions. 



Causation. — Tlie same influences may give rise to chronic that ai'e 

 involved in the causation of acute pleurisy. It may be induced traumatl- 

 oally, and is sometimes due to exposure. More often it proceeds from 

 internal causes which are not understood. 



Symploms . — Coagh, pain and tenderness are frequently wanting, and 

 rarely prominent in this disease. The most marked symptom is the in- 

 creased frequency of the respirations, which may be moderate while at 

 rest, but become evident on exercise. Here, as in the acute form, the 

 embarrassment la breathing will depend upon the amount and rapidity 

 with which the effusion takes place. The pulse generally runs above the 

 normal, and is small and compressible. Appetite is impaired. 



Diarrhoea occurs in some cases, and emaciation may follow, although 

 the strength is often maintained to a marked degree, and the animal be 

 out and take considerable easy exercise. 



Siagnosit. — The symptoms apparent in this disease will aid much, but 

 a positive diagnosis can hardly be reached without auscultation and per- 

 cussion. The signs of liquid effusion are the same in chronic as in acute 

 pleurisy. In the former the amount Is often greater, and the cAntractlon - 

 of the affected side is more marked after absorption. 



Chronic pleurisy Is often associated with other diseases, among them 

 pulmonary consumption and dropsical affections, which, by their indi- 

 vidual symptoms, may be detected. 



PrOffnosis . —Hiai-pVe olironic pleurisy unassooiated with any other 

 serious disease, and occurring in an animal previously healthy, may be 

 recovered from, but a permanent deformity, iq contraction of the affected 

 side is quite certain to result. Death often occurs from associated com- 

 plications. In many cases a breaking down of the lungs fpUows chronic 

 pleurisy, and the disease assumes the form of consumption. In other oases 

 absorption of the effusion may go on to a certain extent, and the animal 



