18 TRANSITION FROM HEALTH TO DISEASE. 



nature of its structure renders it so. The large venous 

 vessels entering into its composition; the intricacy and 

 minuteness with which they ramify; together with their 

 circumlocutory distance from the hearty are all circumstances 

 favorable to such a condition. In very fat old horses, 

 whose work is trifling, it is not an uncommon accident 

 to have the gland burst from congestion ; in which case it 

 displays a mass of partially congealed black blood. 



The Spleen, now and then, acquires an enormous bulk 

 from the effects of long-continued congestion. It ordinarily 

 weighs about three pounds : I have seen it so much enlarged 

 as to weigh upwards of fourteen pounds. 



Congestion of the Mucous Membranes lining the air 

 and alimentary passages, is frequent; at the same time, 

 it appears to be of a very fugitive nature. In these 

 and other membranous structures, the line to be drawn 

 between congestion and inflammation is so fine, that it is 

 hardly possible to speak of one subject without infringing 

 on the other; for that reason, I shall defer the present 

 inquiry until I speak of inflammation. 



A remarkable instance of the efi'ects of congestion is 

 furnished by the case of common frush. Every groom or 

 farrier knows how hazardous it is to arrest this issue, when 

 in the fore feet ; that, in fact, its suppression is apt to be 

 followed by heat of hoof and lameness, — a result owing to 

 congestion taking place in the foot. 



Newly formed Structures, and parts that have been 

 the seat of prior inflammatory attacks, are, in an especial 

 manner, disposed to paroxysms of congestion. The bronchial 

 membranes of horses habitually subject to chronic cough, 

 or afflicted with broken wind, show it during the changes 

 from dryness to moisture. In some horses, so irritable is 

 the mucous membrane of the bowels, that exposure to cold 

 will produce an attack of diarrhoea. 



Serous Congestion. — In those parts of the body in 

 which the vessels exhale a sero-albuminous vapour for the 

 purposes of lubrication, it frequently happens that accumu- 

 lations of this fluid take place, without producing any 



