Percussion. 185 



If the increased clearness is confined to the upper, lower, or 

 posterior border of one or both lungs, the sound being natural 

 over all other parts, it indicates the existence of emphysema of 

 the lungs, a condition almost constant in broken- winded horses. 



If the sound is drumlike over most of the lung it is due either 

 to extensive emphysema or to the presence of air as well as liquid 

 in the cavity of the chest. In the case first noticed there will be 

 the double action of the flank, the weak, dry, husky cough and 

 the wheezing breathing ; in the last there will have been the pre- 

 vious attack of pleurisy, and the application of the ear to the 

 chest will detect a splashing sound constant or heard only at in- 

 tervals or on rising. This should be carefully distinguished from 

 abdominal gurgling. 



Diminished resonance, noticed over an entire lung, may be due 

 to congestion or oedema of the lung, to the formation of a thick 

 false membrane over the inner surface of the ribs or to a false 

 membrane enveloping the lung and preventing its due distension. 

 Congestion will be distinguished by the blueness of the mucous 

 membranes and the presence of a crepitant sound heard on auscul- 

 tation. Pleurisy is known by the tenderness on percussion or on 

 pinching the intercostal spaces, and by the presence in many 

 cases of a friction sound. The sound may be further lessened in 

 cattle by the deposit of tubercle on the inner side of the ribs, or 

 the extensive deposition of miliary tubercle throughout the sub- 

 stance of the dung. 



Absence of resonance, the sound brought out by percussion 

 being similar to that obtained by practising it over the muscular 

 masses of the haunch, is always partial. It is due either to he- 

 patization or to water in the chest. Hepatization is distinguished 

 by its rarely affecting the lower thirds of both lungs at once, by 

 the presence of a crepitating rile round the margin of the area of 

 dullness, and by the increased resonance and respiratory murmur 

 over the sound parts of the same and the opposite lung. In water 

 in the chest, on the other hand, a friction sound and much tender- 

 ness precedes the dullness ; the tenderness continues and the dull- 

 ness reaches the same height on both sides of the chest, in the 

 case of the horse. In the ox, water may exist on one side of the 

 chest only, but the tenderness on pressure and the absence of any 

 crepitation serve to distinguish the case from pneumonia. In the 



