186 INFLAMMATION OF THE LUNGS. 



PNEUMONIA— INFLAMMATION- OF THE LUNGS. 



The intimate structure of the lungs has never been satisfacto 

 rily demonstrated. They appear, however, to be composed of 

 minute cells or pouches, into which the air is at length con 

 ducted, and over the delicate membrane constituting the divi- 

 sions of which myriads of minute blood-vessels are ramifying. 

 The blood is not merely permeating them, but it is undergoing a 

 vital change in them ; there is a constant decomposition of the 

 air, or of the blood, or of both ; and, during the excitement of 

 exercise, that decciaj ^^^ition proceeds with fearful rapidity. Then 

 it can readily be ccnceivvl tLat a membrane so delicate as this 

 must be in order thit it^ ii t;rp)sition shall be no hindrance to 

 the arteiialization of the blood ; so fragile also, and so loaded 

 with blood-vessels, will be e.TCoedingly subject to inflammation, 

 and that of a mosi, dangerous character. 



Inflammation of the substance of the lungs is the not unfre- 

 quent consequence of all th' liseases of the respiratory passages 

 that have been treated on. Catarrh, influenza, bronchitis, if 

 neglected or badly managed < r, sometimes in spite of the most 

 skilful treatment, will spread along the mucous membrane, and 

 at length involve the termination of the air-passages. At other 

 times, there is pure pneumonia. This cellular texture is the 

 primary seat of inflammation. It is often so in the over-worked 

 horse. After a long and hard day's hunt, it is very common for 

 horses to be attacked by pure pneumonia. 



The following are the most frequent causes of pneumonia. A 

 sudden transition from heat to cold ; a change from a warm sta- 

 ble to a colder one ; a neglect of the usual clothing ; a neglect 

 even of some little comforts ; riding far and fast against a cold 

 wind, especially in snowy weather ; and loitering about when 

 unusual perspiration has been excited. 



It has not unfrequently happened that when horses have been 

 turned out too early to grass, or without gradual preparation, 

 pneumonia has supervened. Few are, under any management, 

 BO subject to pneumonia as those which, in poor condition and 

 without preparation, are turned into salt-marsh. 



windpipe as possible, are of material service ; and if the inflammation ex- 

 tends up the windpipe, the setons should also so extend, or the course of 

 the windpipe may be blistered. Physic should be avoided. With regard 

 to bleeding,, this must depend entirely upon the state of the pulse. Some- 

 times its weakness entirely forbids depletion, and, on the other hand, 

 several bleedings have been required. As a general rule, however, the 

 Vjlood-letting should not be very copious. 



