150 MANUAL OF EQUINE MEDICINE. 



Acute Congestion is the more frequent of the two forms 

 in the horse, and is the more easily recognised. When 

 accompanied by hsemorrhage from rupture of the pulmonary 

 capillaries, it is sometimes spoken of as pulmonary apoplexy. 



Acute congestion is the result of sudden exertion in an 

 untrained condition, exhaustion, badly-ventilated stables, 

 and various other causes which under some conditions 

 induce this malady, but under other circumstances are 

 provocative of bronchial or common catarrh. 



Passive Congestion may be due to retarded venous circu- 

 lation, as in mitral and some other cardiac diseases, or to 

 general exhaustion, resulting in some fevers, and other 

 debilitating affections. 



When an animal in an untrained condition is suddenly 

 called upon to perform any unusual exertion, the cardiac, 

 pulmonary and muscular systems may not be able to respond 

 to the increased strain put upon them. Under these cir- 

 cumstances — as, for instance, when an unprepared horse is 

 suddenly put into the hunting-field — the heart's action 

 becomes embarrassed and tumultuous, the blood accumu- 

 lates in the pulmonary capillaries, and the breathing 

 becomes more and more distressed, until, at length, he may 

 die of suffocation, consequent on overloading and engorge- 

 ment of the lungs with deoxidized blood. Under careful 

 training the cardiac and other systems are gradually accus- 

 tomed, by regular and careful exercise, to perform additional 

 work, and their tone and vigour is enhanced, and the 

 system responds duly to even severe strains. 



Symptoms. — The symptoms of the acute forms of 

 pulmonary congestion are in most instances of a very severe 

 tyj)e, and the affection is specially characterized by very 

 great dyspnoea. The horse stands with his limbs out- 

 stretched, and gasps for breath. All the available ordinary 

 and extraordinary muscles of respiration are called into 



