PLEURITIS. 173 



The accLimulation of fluid in the pleural sac, and the develop- 

 ment of morbid growths in contact with the membrane, are 

 also liable to set up pleurisy. 



(3.) Exposure to cold and damp and sudden atmospheric 

 changes. 



(4.) Certain enzootic and epizootic fevers and other constitu- 

 tional diseases. 



For example, pleurisy is a frequent concomitant of some 

 of the specific fevers, as, for example, influenza, and of con- 

 stitutional diseases, as rheumatism, suppurative phlebitis and 

 pyaemia. 



Symptoms. — The fever of acute pleurisy is ushered in by 

 a slight chill or by an actual rigor. The animal may be 

 restless, and show signs of pain, aggravated by breathing, 

 which, though accelerated, is performed carefully. The 

 pain is increased when the horse is moved round, and the 

 chest wall is very tender to pressure or when percussed, and 

 the expression is anxious and indicative of great pain. The 

 pulse is increased in frequency, but its ratio to the breath- 

 ing is only slightly disturbed, and is hard and more incom- 

 pressible than in pneumonia. The temperature is raised to 

 103° or 104°, the mouth is hot and dry, but the expired air 

 is not so heated as in pneumonia. 



In the inspiratory act the ribs are fixed, and in conse- 

 quence of this there may be observed a furrow on the line 

 of demarcation, called the pleuritic ridge. This extends 

 from the bottom of the posterior part of the chest, and 

 runs obliquely in an upward and backward direction to 

 the anterior spine of the ilium. Cough is a frequent 

 symptom of pleurisy. It is shorter and more painful than in 

 pneumonia, and is attended with little or no expectoration. 



If the chest be examined a friction sound, or ^ dry leather 

 creaking,' as it is sometimes termed, may be heard. This is 

 owing to the rubbing of the two pleural surfaces together. 



