174 MANUAL OF EQUINE MEDICINE. 



This sound appears as if close under the ear, and as the 

 king moves to and fro it is consequently double. It is not 

 heard if the breathing cease, and the area over which it is 

 audible may be very limited. 



The friction may in many instances be felt by placing 

 the hand over the involved area of the chest-wall. The 

 vesicular murmur is weakened, and percussion in this dry 

 stage reveals nothing. 



The inflammation may now subside, with the effusion of 

 very little lymph, in which case the friction sound passes 

 away. If, on the other hand, the fluid gradually accumulates, 

 in this case also this sound disappears, as the two roughened 

 surfaces are separated by a layer of fluid. 



When absorption of the fluid takes place, the two layers 

 come together again, the sound is heard again, and is called 

 'redux friction.' 



With the effusion of fluid the more active febrile 

 symptoms and pain abate, the temperature may fall a little, 

 the pulse is less jarring, and the pleuritic ridge less distinct. 



If the effusion now accumulate in very large amount, the 

 symptoms become more serious ; the pulse is increased to 80 

 beats or more per minute, and is of smaller volume, and may 

 be irregular in rhythm and volume. The respirations become 

 more laboured, and the difficulty of breathing may be \rery 

 great ; the flanks heave, and there is flapping of the nostrils. 



This dyspnoea is to be attributed to compression of the 

 structure of the lung by the accumulated fluid, which, if 

 not absorbed, is spoken of as dropsy of the chest, or hydro- 

 thorax. 



The animal's head is generally protruded, and dropsical 

 swellings appear in various parts. They are usually first 

 noticed along the inferior part of the thorax, spreading 

 along the floor of the abdomen, and may at length involve 

 the limbs. 



