284 PNEUMONIA. INFLAMMATION OF THE LUNGS. 



destroyed, inflammation is produced, meclianical injury is effected, the 

 vessels are ruptured, blood is poured into the interstitial texture, and 

 congestion and intense inflammation, with all their train of fatal conse- 

 quences, ensue. 



The following are the most frequent causes of pneumonia. A sudden 

 transition from heat to cold ; a change from a warm stable to a cold 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 ; 

 loitering about when unusual perspiration has been excited ; waiting 

 tediously by the side of a covert on a chilly blowing morning. 



It has, but not frequently, happened that when horses have been turned 

 out too early to grass, or without gTadual preparation, pneumonia has 

 supervened. Few are, under any management, so subject to pneumonia 

 as those who, in poor condition and without preparation, are turned into a 

 salt-marsh. 



On the other hand, a sudden and considerable change from cold to heat 

 will very probably be followed by inflammation of the lungs. Many horses 

 perish in the dealers' stables from this cause. The circulation is consider- 

 ably quickened ; more blood, and that with more than natural rapidity, is 

 driven through the lungs, previously disposed to take on inflammatory 

 action. The sudden removal from a heated stable to the cold air has also 

 much to do with the production of disease. 



Whether it is the consequence of previous disease of the respiratory 

 passages, or that inflammation first appears in the cellular texture of the 

 lungs, pneumonia is usually ushered in by a shivering fit. The horse is 

 cold all over ; this, however, soon passes off, and we have general warmth, 

 or heat of the skin above the usual temperature, but accompanied by cold- 

 ness of the extremities — intense deadly coldness. This is a very diagnos- 

 tic symptom. It will seldom deceive. It is an early symptom. It is 

 found when there is little or no constitutional disturbance ; when the pulse 

 is scarcely affected, and the flanks heave but little, but the horse is merely 

 supposed to be dull and off" his food. It is that by Avhich the progress of 

 the disease may be unhesitatingly marked, when many scarcely suspect its 

 existence. 



The pulse is always, even at first, much increased in rapidity, but is 

 rarely or never hard ; it is obscure, oppressed; it rises at on?e from thirty- 

 two or three to fifty ; with increased danger it is found at seventy or 

 eighty ; and in fatal cases from one hundred to one hundred and twenty. 

 The heart is labouring to accomplish its object ; the circulation through 

 the lungs is impeded ; the vessels are engorged — they are often ruptured ; 

 blood is extravasated into the air-cells ; it accumulates in the right side 

 of the heai-t and in the larger vessels ; and in the venous circulation gene- 

 rally there is a mechanical obstruction which the heart has not the power 

 to overcome. Hence the obscure, oppressed pulse ; the ineflTectual attempt 

 to urge on the blood ; and hence, too, the remarkable result of bleeding in 

 inflammation of the lungs, for the pulse becomes rounder, fuller, quicker. 

 When blood is abstracted, a portion of the opposing force is removed, and 

 the heart being enabled to accomplish its object, the pulse is developed. 



It is only, however, in the early insidious stage that the flanks are 

 occasionally quiet. If the compressibility of the lungs is diminished by 

 the thickening of the membrane, or the engorgement of the vessels, or the 

 filling of the cells, it will be harder work to force the air out ; there must 

 be a sti'onger effort, and the pressure which cannot be accomplished by one 

 effort is attempted over and over again. The respiration is quickened — 

 laborious : the inspiration is lengthened ; the expiration is rapid ; and 

 when, after all, the lungs cannot be compressed by the usual means, every 



