no VETERINARV HOMCEOPATHV. 



termiuatiiig in minute pouches or air cells; like the bronchial 

 tubes the blood vessels which accompany them also become 

 smaller and smaller until they are described as capillaries, and 

 the membranes which form the walls of tubes and capillaries are 

 so fine that the blood is readily exposed to the action of the air in 

 the bronchial cells and the interchange of the chemical constitu- 

 ents requisite for the maintenance of liie here takes place. The 

 larger bronchial tubes are formed externally of a tough mem- 

 brane, next to which is a layer of muscle and the internal parts or 

 lumen of the tubes are lined with mucous membrane; it is desir- 

 able to remember this in order to properly appreciate the meaning 

 of bronchitis, one of the forms of disease hereafter to be referred to. 

 Thus in considering the morbid conditions to which the lungs are 

 liable it is uecessary to bear in mind that there are three distinct 

 parts which may either be separately and individuall}^ the seats of 

 inflammation, or as is more generally the case in the horse, all 

 three may be affected at one and the same time; namely, the 

 bronchial tubes; the true lung substance and the pleura; when 

 these are the seat of inflammation they are described respectively 

 as bronchitis, pneumonia and pleurisy. 



BRONCHITIS. 



Inflammation of the bronchial tubes, like all kinds of inflamma- 

 tion is preceded by congestion or excess of blood to the parts, and 

 if only this congested condition is recognized in time, the difficulty 

 and responsibility of treatment are materially modified, but unfor- 

 tunately it is not often that during this stage the absolute state of 

 affairs is discerned in the horse. Bearing in mind, what has 

 already been stated, that the bronchial tubes are continuations of 

 the windpipe, and that this portion of the lungs is of necessity 

 the first to feel the effects of cold air it is not surprising that as a 

 rule bronchitis develops itself before either pneumonia or pleurisy, 

 though it must be clearly understood this is not an absolutely 

 fixed rule. 



Exposure to cold and a consequent general lowering of the 

 body temperature, more frequently than anything else accounts 

 for bronchitis, but why the lungs should be the particular organs 

 upon which the force of the inflammatory process is ultimately 

 centered is not quite clear unless predisposing weakness either 



