DISEASES OF THE AIR-PASSAGES OF HORSES. 
403 
Bronchitis is an invariable complication with hroken-wind. I 
am of opinion that the latter is the consequence of the former. 
The causes of broken-wind have been sought where the effects 
could only be found,—in the anatomical characters of the disease. 
The remote causes, however, will be more rapidly traced to the 
muco-digestive surface; to damaged food, hay and oats in parti¬ 
cular, and an injudicious administering of it, as the ordinary ex¬ 
citing causes. The mucous surfaces of the intestinal tube are first 
irritated, their organic actions altered, and the morbid impressions 
propagated to other related organs in a greater or less degree. To 
this succeeds absorption of morbid elements into the circulating 
huids, exciting, depressing, or altering the vital actions through 
the vascular system. By these modes of action united, impressions 
of an exciting nature are made upon the muco-respiratory surfaces, 
giving rise to inflammatory action of the sthenic form, generally of 
a low grade of intensity. This is, apparently, the most frequent 
source of the disease: still the respiratory surfaces are excited by 
causes which operate simultaneously upon the cutaneous and the 
respiratory mucous membrane; and although inflammatory action 
—the product of these latter causes—does sometimes terminate in 
alteration of structure and function of the muco-respiratory surface, 
and ultimately in broken-wind, it is not, comparatively, an equal 
mode of production. 
By whichever of these sources bronchitis, in a chronic or sub¬ 
acute form, is propagated, the lesions of structure and dyspnoea, 
designated broken-wind, are consequences of that affection; indeed, 
this complication is continuous, by the alterations of the one reci¬ 
procating upon the other. 
Inflammation of mucous tissue, as of every other, may continue 
of a low grade of intensity, and of the chronic kind, for a long and 
indeterminate period, and be of so mild a form and of so obscure 
a character, as even to escape observation for a considerable pe¬ 
riod. This is to be attributed to the slow and gradual ])rogress of 
the inflammatory action; and, as I have previously stated when 
speaking of chronic bronchitis, besides being a termination of the 
acute form, it also occurs as a primary affection. It is of the pri¬ 
mary form that broken-wind is consecutive : upon this point I am 
desirous of being clearly understood; and 1 conceive tliat what 1 
am about to state will be obvious to my readers. 
In acute bronchitis the expectoration of mucus is abundant, and 
it is by particular attention to the discharge of the sputa that we 
are enabled to judge that it has assumed the chronic type,— 
namely, by its continuance for a long time in undiminished (quan¬ 
tity, and by its purulent (juality and mitigation of the urgent 
symptoms. In its primary form, when it occurs as the precursor 
