522 BROKEN WIND. 



That it does follow sudden and severe exertion in conditions 

 of the animal system where the limg-strncture is unprepared 

 for such may be possible, but it is certainly not a common 

 mode of its production. 



c. Anatomical Characters. — The anatomical characters 

 which are observable on examining animals which have died 

 while suffering from this disease are rather variable in cha- 

 racter, but tolerably constant as to the organs where lesions 

 are usually met with. 



The extent of these changes does not seem to have a direct 

 relation to the severity of symptoms exhibited during life, or 

 the period over which these have been distributed. The 

 organs in connection with which we may expect to find altera- 

 tions of structure are in the thorax — the lungs and heart; in the 

 abdomen — the gastro-intestinal canal, particularly the stomach. 



In many instances the examination of the lungs of horses 

 which have died during the earlier stages of broken-wind has 

 resulted in the discovery of nothing abnormal ; others show 

 merely a deficiency of resilience, a slight want of colour, and 

 greater buoyancy when floated in water than normal pul- 

 monary tissue. 



When the disease has existed for some time, the usual 

 appearances are pallor, retention to a great extent of bulk, and 

 indisposition to collapse, with emphysema, vesicular and inter- 

 lobular. The former of these structural changes shows itself 

 as small bags or vesicles containing air beneath the enveloping 

 serous covering of the organs ; these are irregularly distributed, 

 or they may be grouped together at particular situations ; 

 the latter appears as an infiltration and distension with air of 

 the fine connective-tissue subsisting between the air- vesicles 

 and minute air-tubes ; this air, by pressure, may be passed along 

 from one part of the connective-tissue to another. The minute 

 bronchi seem thickened, their walls in some appearing to have 

 undergone degenerative changes, while the larger air-tubes are 

 lessened in character from hypertrophy of the lining mem- 

 brane. The pallor of the pulmonary tissue as a whole is 

 probably owing to the lessening of the blood-supply as well as 

 to intimate tissue-change, the interlobular emphysema, by 

 pressure on the capillary plexuses, having these effects. The 

 emphysematous condition of the lung-tissue is, as a rule, 



