96 DISEASES OF THE LUNGS. 



will have proportionate results in the animal economy. The 

 inflammatory attacks of the lungs to which young horses are 

 so especially obnoxious, are very often cases of bronchitis; 

 and even of such as are peripneumonia, bronchitis is a 

 common precedent or accompaniment. In fact, there 

 exist very few diseases of lung in which bronchitis is notj 

 in some degree, present, either in a primary or secondary 

 form. 



The TERMINATIONS or consequences of bronchitis are such 

 as to make us anxious to institute such treatment at its com- 

 mencement as is most likely to lead to their prevention ; it 

 being, of all others, the most fertile source of those organic 

 changes which in particular tend to shorten or impair the 

 animal's wind. Roaring and thick wind commonly have 

 their foundation laid in bronchitis. The bronchial membrane 

 during the early stages of disease will be found in a state of 

 congestion or turgescence ; in the sequel it is very likely to 

 become thickened in substance — hypertrophied, as it is 

 called — in which condition the calibre of the bronchial tubes, 

 the small ones in particular, will suffer considerable diminu- 

 tion, and consequently become but comparatively imperfect 

 conductors of the respired air. In the larger tubes the 

 lining membrane is furnished with follicles, which impart to 

 it the true mucous character ; but in the very small ones, as 

 we approach the air-cells, it has been found to bear more 

 similarity to a serous membrane, and on this account becomes 

 still more disposed to take on the plastic or adhesive kind of 

 inflammation which not only gives rise to hypertrophy, but 

 occasionally to solid eff'usion and agglutination of the sides 

 of the tubes, obliterating their cavities, and converting them 

 into mere chords, the same as happens when inflammation 

 is set up in the interior of blood-vessels ; and this may even 

 go so far as to block up and annihilate the air-cells. The 

 eff*ect of this will be to shorten or " thicken^' the wind, to 

 compensate for which the animal will make additional efforts 

 in respiration, and the result is likely to be dilatation of the 

 vicinous tubes and air-cells. It would appear that this pro- 

 cess commonly commences in the smaller and makes way 

 into the larger tubes, and from the circumstance of secretion 



