THICK-WIND. J93 



sometimes interfering^ not at all with the health of the animal, that it 

 is scarcely worth while to persevere in any mode of treatment that is not 

 evidently attended with speedy benefit. The principal consideration to 

 induce us to meddle at all with chronic cough is the knowledo-e that 

 horses afflicted with it are more liable than others to be affected by chano-es 

 of temperature, and that inflammation of the lungs, or of the respiratory 

 passages, often assumes in them a very alarming character; to which, 

 perhaps, we may add, that a horse whh chronic cough cannot legally or 

 properly be warranted sound. 



When chronic cough chiefly occurs after eating, the seat of the disease 

 is evidently in the substance of the lungs. The stomach distended with 

 food presses upon the diaphragm, and the diaphragm upon the lungs ; 

 and the lungs, already labouring under some congestion, are less capable of 

 transmitting the air. In the violent effort to discharge their function, 

 irritation is produced ; and the act of coughing is the consequence of that 

 irritation. This is aUied with, or S9on runs into 



THICK-WIND. 



Thick-wind consists in short, frequent, and laborious breathings, and 

 especially when the animal is in exercise; the inspirations and expirations 

 often succeeding each other so rapidly as evidently to express distress, and 

 occasionally almost to threaten suffocation. Some degree of it frequently 

 exists in round-chested and fat horses, that have little or no breeding. 

 The reason of this is sufficiently plain. The circular chest affords sufficient 

 room for the expansion of the lungs when the animal is at rest, and suffi- 

 cient room for the accumulation of a great deal of fat and flesh ; but when 

 the horse is strongly exercised, the circulation of the blood is hurried, and 

 its change from arterial to venous, or from vital to empoisoned blood, is 

 more rapid. The circular chest cannot then enlarge to any great degree : 

 yet the blood must be purified in greater quantity, and therefore what 

 cannot be done by increase of surface, must be accomplished by frequency 

 of action. Heavy draught horses are invariably thick winded, and so are 

 almost all horses violently exercised on a full stomach. 



A horse labouring under any inflamr -tory affection of the lungs is 

 thick-winded, because the pain which he leels in the act of breathing will 

 not permit him to respire deeply, and therefore, he must breathe quickly. 

 A horse unused to exercise is thick-winded, because the lungs will not 

 soon accommodate themselves to a new and laborious action. 



The principal cause, however, of thick wind is previous inflammation, 

 and particularly inflammation of the bronchial passages. The throwing 

 out of some fluid, which is capable of coagulation, is the result, or the 

 natural termination of inflammation. This deposit in the substance of 

 the lungs, or in the bronchial tubes, from inflammation of these organs, 

 must close many of the air-cells, and lessen the dimensions of others. Then 

 if the cells, fewer in number and contracted in size, be left for the purposes 

 of breathing, the rapid and laborious action of the lungs must supply the 

 deficiency, and especially when the animal is put in that state in which he 

 requires a rapid change of blood. 



The examination of thick-winded horses has thrown considerable light 

 on the nature of the disease. In the majority of instances some of the 

 small air-cell? have been found filled up with a dense substance of a blue 

 or darker colour. In others, the minute passages leading to the cells have 

 been diminished, and almost obliterated, the linings of these passages 

 being unnaturally thickened, or covered with hardened mucus ; and where 



