228 BOARD OF AGRICULTURE. [Pub. Doc. 



So many of the causes of double suppression (diminution of the 

 murmur in both lungs) are entirely unassociated with the chest 

 that for our present purpose, it becomes a symptom of no value 

 whatever, although upon some occasions it is associated with the 

 disease under consideration. 



On Absence of Respiratory Murmur. 

 Complete absence of the respiratory sounds in one lung, or in 

 portions of both lungs, exists in connection with cases of lung 

 fever, dropsy of the chest and tuberculosis. In the latter case the 

 entire absence of sound in the part will be due to a consolidation 

 of the lung tissue, when pneumonia is in complication with the 

 tuberculosis ; or else to large deposits of the purulent or cheesy 

 tuberculous matters. A description of the further modification of 

 these sounds, the detection of cavities, etc., are entirely too intri- 

 cate for the present purpose. 



Eales. 



In addition to the abnormal sounds already described, which are 

 really no more than modifications of the natural sounds, there are 

 another series which are essentially distinct from the sounds of 

 health, and which are called rales or rattles. Very shortly stated, 

 these sounds are of two sorts : a dry rale, which is a more or less 

 wheezing or musical note produced by an abnormal narrowing of 

 a bronchial tube ; a sound that is coarse or fine, depending upon 

 the size of the tube in which it is produced ; and a moist rale, pro- 

 duced by the passage of air over or through mucous or other fluid 

 contained in the tubes. This rale is also coarse or fine. 



Both of these sounds, as well as their many complications and 

 divisions, will arise from any disease of tlie lung in which the 

 bronchial tubes become implicated ; and, inasmuch as these tubes 

 are implicated in a large number of the cases of tuberculosis of the 

 lungs, some or all of these notes are very frequently to be heard in 

 one or another part of the chest of the affected animal. Sometimes 

 they will be found to extend over a large area, and will be easily 

 heard ; at other times so small a portion of the lung will be changed 

 that the sound will only be discovered after a most careful exami- 

 nation. When it is discovered, unless its presence can otherwise 

 be clearly accounted for, the animal should be looked upon with 

 great suspicion. 



All sounds, normal and abnormal, are very much more difficult 

 to hear in fat animals, or in those having round chests ; and in all 

 cases the lung sounds will be very much easier to hear if the 

 animal is driven about actively for a few minutes just previous to 



