THICK-WIND. 275 



with a peculiar sound like half roaring — the inspirations and expirations being- 

 rapid, forcible, but equal. In the second, the breathing is also hurried, but the 

 inspiration does not differ materially from the natural one, while the expiration 

 is difficult, or doubly laborious. The changes of structure which accompany 

 these states of morbid respiration are as opposite as can bo imagined. Indura- 

 tion of the substance of the lungs, diminution of the number or the caliber of 

 the air-passages, are the causes of thick-wind. If the portion of lung employed 

 is lessened, or the bronchial tubes will not admit so much air, the quick succes- 

 sion of efforts must make up for the diminished effect produced by each. In 

 broken-wind there is rupture of the air-cells, and an unnatural inter-com- 

 munication between them in the same lobule, or between those of the neigh- 

 bouring lobuli. The structure of the lung, and the discharge of function, 

 and the treatment, too, being so different, these diseases require separate con- 

 sideration. 



THICK-WIND. 



When treating of pneumonia, it was observed, that not only are the vessels 

 which ramify over the delicate membrane of the air-cells gorged with blood, but 

 they are sometimes ruptured, and the cells are filled with blood. The black, 

 softened, pulpy appearance of the lungs thus produced, is the rottenness of the 

 groom and farrier, proving equally the intensity of the inflammation and that 

 it is of recent date. If the horse is not speedily destroyed by this lesion of the 

 substance of the lungs, the serous portion of the effused blood is absorbed, and 

 the solid becomes organised. The cells are obliterated, and the lung is 

 hepatized, — its structure bears considerable resemblance to that of the liver. 

 This may occur in patches, or it may involve a considerable portion of 

 the lung. 



If a portion of the lung is thus rendered impervious, the remainder will have 

 additional work to perform. The same quantity of blood must be supplied with 

 air ; and if the working part of the machine is diminished, it must move with 

 greater velocity as well as force — the respiration must be quicker and more 

 laborious. This quick and laboured breathing can be detected even when the 

 animal is at rest, and it is indicated plainly enough by his sad distress when he 

 is urged to unusual or continued speed. The inspirations and the expirations 

 are shorter, as well as more violent ; the air must be more rapidly admitted 

 and more thoroughly pressed out ; and this is accompanied by a peculiar sound 

 that can rarely be mistaken. 



We may guess at the commencement of the evil, by the laborious heaving of 

 the flanks; but by auscultation alone can we ascertain its progress. The in- 

 crease of the crepitus will tell us that the mischief is beginning, and the cessation 

 of the murmur will clearly mark out the extent of the congestion. 



The inflammatory stage of the disease having passed, and comparative health 

 being restored, and some return to usefulness having been established, — the 

 horse being now thick-winded, auscultation will be far more valuable than is 

 generally imagined. It will faithfully indicate the quantity of hepatization, 

 and so give a clue to the degree of usefulness, or the extent to which we may 

 tax the respiratory system ; and it will also serve to distinguish, and that very 

 clearly, between this cause of thick-wind, and the morbid changes that may 

 have resulted from bronchitis, or thickening of the parietes of the air-passages, 

 and not the obliteration of the air-cells. 



Of the Treatment little can be said. We know not by what means we can 

 excite the absorbents to take up the solid organised mass of hepatization, or restore 

 the membrane of the cells and the minute vessels ramifying over them, now 

 confounded and lost. We have a somewhat better chance, and yet not much, 



t2 



