DIURETICS. 21 5 



animal. The kidneys are two large glandular bodies, placed under the 

 loins, very much the shape of a kidney bean. The right kidney is most 

 forward, lying under the liver; the luit is pushed more backward by the 

 stomach and spleen. A large artery runs to each, carrying not less than a 

 sixth part of the whole of the blood that circulates through the frame. Tlie 

 artery divides into innumerable little branches, most curiously complicated 

 and coiled upon each other; and the blood, traversing these convolutions, 

 has its watery parts and others, the I'etaining of which would be injurious, 

 separated from it. 



The fluid thus separated varies materially both in quantity and composi- 

 tion, even during health. There is no animal in which it varies so much 

 as in the horse. There is no organ in the animal so much under our com- 

 mand as the kidney ; and no medicines ai*e so useful, or may be so injuri- 

 ous, as diuretics. In speaking of fever and inflammation of the lungs, 

 and, indeed, inflammation generally, we have recommended the use of nitre 

 and digitalis, not only on account of their febrifuge or sedative effects, but 

 because they act as diuretics. They stimulate the kidneys to separate more 

 aqueous fluid than they otherwise would do, and thus lessen the quantity 

 of blood ; the quantity which the heart is labouring to circulate through 

 the frame, and the quantity which is determined or driven to a part already 

 ovei-loaded. The main objects we have to accomplish in these diseases is to 

 reduce the force of the circulation, and to calm the violence of excitement ; 

 and diuretics, by lessening the quantity of blood, are useful assistants in 

 accomplishing these purposes. It is, however, in the varieties of dropsy 

 that their benefit is most evident. The horse is more subject to efl'usions ot 

 fluid in particular parts than any other domestic animal. Swelled legs is a 

 disease peculiar to him. The ox, the sheep, the dog, the ass, and even the 

 mule, have it very seldom; and for the removal of this deposit of fluid in 

 the cellular substance of the legs we have recourse to diuretics. The kidneys 

 are stimulated to separate more than the usual quantity of water from the 

 blood. In order to make up this deficiency in quantity, the absorbents set 

 to work, and they take up and pour into the circulation the fluid which had 

 been effused in the legs. The legs of many horses cannot be rendered 

 fine or kept so, without the use of diuretics ; nor can grease, often con- 

 nected with these swellings, producing them, or caused by them, be other- 

 wise subdued. We therefore rank diuretics among the most useful of 

 the veterinary medicines. 



In injudicious hands, however, these medicines are sadly abused. 

 Among the absurdities of stable management there is nothing so injurious 

 as the frequent use of diuretics. Not only are the kidneys, so often over- 

 excited, weakened, disposed to disease, but -the whole frame becomes 

 debilhated; for the absorbents have carried away a great part of that which 

 was necessary to the health and condition of the horse, in order to supply 

 the deficiency of blood occasioned by the inordinate discharge of urine. 

 There is likewise one important fact of which the groom or the horseman 

 seldom thinks ; that when he is removing these humours by the imprudent 

 use of diuretics, he is only attacking a symptom or a consequence of dis- 

 ease, and not the disease itself. The legs will fill again, and the grease 

 will return. While the cause remains, the efTect will be produced. We 

 shall say more of this when we treat particularly of the diseases of the 

 extremities. 



■ In the administration of diuretics there are two things to be chiefly 

 attended to. The first is that which seems to be contradictory, but the good 

 effect of which the testimony of every intelligent man will confirm ; let the 

 horse have plenty to drink. Not only will inflammation be prevented, but 



