DIURETICS. 215 



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

 loins, very much of the shape of a kidney bean. The rig'ht kidney is most 

 forward, lying' under the liver ; the left 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. 

 The artery divides into innumerable little branches most curiously compli- 

 cated and coiled upon each other ; and the blood, traversing these convo- 

 lutions, has its watery parts and others the retaining 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 that animal so much under our 

 command as the kidney ; and no medicines are so useful, or may be so 

 injurious, 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 

 overloaded. The main objects we have to accomplish in these diseases 

 is to reduce the force of the circulation, and to calm the violence of excite- 

 ment ; and diuretics, by lessening the quantity of blood, are useful assist- 

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

 dropsy that their benefit is most evident. The horse is more subject to 

 eifusions of 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 connected with these swellings, producing them or 

 caused by them, be otherwise 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 

 debilitated, 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 disease, and 

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

 While the cause remains, the effect will be produced. We shall say more 

 of this when we treat particularly of these 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— /e^ the horse 

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

 operation of the medicine will be much promoted. If more water, thaa 



