CHRONIC DISEASES OF THE AIR-PASSAGES. 131 



- Ill some cases of disease somewhat similar to strangles, 

 Mr. Carlisle found the Eustachian cavities full of pus, and he 

 had recourse to an operation, by which he evacuated them with 

 success; and he relates the cases in the Veter mariayi fov Sep- 

 tember, 1841. 



Although strangles is principally confined to young horses, yet 

 a disease, in every respect similar, sometimes appears in the form 

 of an epidemic, and principally in flirmers' stables. It is then 

 by no means confined to young horses, but attacks all ages, and 

 is attended by accompanying symptoms of a severe character. 



The treatment should be regulated by the same principles we 

 have laid down, recourse being had, however, to more active 

 counter-irritation, either by blisters or setons, to obviate the 

 severe inflammatory affections of the windpipe which often 

 attend. — Ed.] 



CHAP. XXVIII. 



CHRONIC DISEASES OF THE AIR-PASSAGES. 



Chronic Cough. 



[We. have spoken of cough as a symptom of catarrh, or rather 

 of inflammation of the larynx ; and although we have now to 

 consider it under a distinct designation, it is yet in all cases a 

 symptom of diseased action, rather than a disease itself. 



There are various descri{)tions of cough, such as hard, soft, 

 dry, short, strong, weak, and convulsive cough. These nume- 

 rous distinctions will, however, answer no useful purpose. It 

 will be sufficient for us to distinguish the short dry coufjh of 

 broken wind, which is familiar to all practised ears ; the dry, or 

 cough loithout discharge ; and the cough attended by an increased 

 secretion of mucus. 



Cough, indeed, denotes the presence of some irritation, and is in 

 fact the noise made by the forcible endeavour to expel this cause 

 of irritation; for instance, in catarrh there may be a great 

 increase in the secretion of mucus, so much so that if not 

 removed it will threaten suffocation. The entrance to the wind- 

 pipe is lined by a membrane endowed by means of nerves with 

 the most delicate sensibility. The presence of mucus on this 

 part produces irritation. The sensation is instantaneously sent 

 to the brain, and thence, by means of the nerves of motion, an 

 impression is conveyed to the diaphragm and abdominal muscles, 

 by which these parts are thrown into violent action ; air is rapidly 

 expelled from the lungs through the windpipe, carrying with it 

 most probably the offending object ; and thus a cough is produced. 



K 2 



