BEONCHITIS. 573 



tubes, which is limited to the first stage of the disorder, but 

 depends on the rigidity of the tubes from congestion of their 

 walls, and especially of their mucous lining. A veterinarian 

 recognises the same noise on applying his ear to the trachea 

 that he detects on galloping a roarer. In the roarer the 

 ' whistle ' or roar is produced by a diminution in the calibre 

 or rigidity of the larynx or trachea, and in bronchitis there 

 is a harsh sound called ' rhonchus.' This roar (in veterinary 

 language) is chiefly confined to the larger bronchi, and is best 

 heard on applying the ear at the root of the neck, just where 

 the trachea passes into the chest. The difficulty with which 

 air is drawn into the lungs, coupled with the roar, would 

 indicate an obstruction in the passage of air through the 

 tubes, which Dr Watson has said is mostly occasioned by 

 portions of viscid, half-solid mucus, which adhere to the 

 membrane, cause a virtual constriction of the air-tubes, and 

 act as vibrating tongues while the air passes by them. " It 

 seldom happens/' says Dr Watson, " that the rhonchus can- 

 not be temporarily got rid of by a vigorous cough." 



As bronchitis fairly sets in, a secretion, at first watery and 

 frothy, is expelled in coughing. The mucus becomes thicker 

 and more purulent, containing solid masses which may ob- 

 struct some bronchial tubes. This leads to symptoms of 

 dyspnoea, which I have seen very severe in the horse and 

 dog. The muco-purulent discharge is sometimes very 

 abundant, and relieves the animal much, being expelled 

 readily by a vigorous cough, which is less frequent and 

 much less troublesome than the cough of the first stage of 

 bronchitis. 



I have observed total loss of respiratory murmur over cer- 

 tain portions of lung from obstructions within the bronchi, 

 and I have also seen abscesses form as the result of severe 

 acute bronchitis. 



