THE KIDNEYS 251 



urine, are too prone to use it with indiscretion. These 

 diuretic medicines, if used in too great quantities, 

 stimulate the kidneys to separate more of the watery 

 fluid than they do in a natural and healthy condition, 

 and the effect is to lessen the quantity of blood. 

 Although this property in nitre is advantageous in 

 many disorders where the heart is burdened by the 

 pressure required to force the blood forward through 

 the arteries in inflammatory complaints, it is easy to 

 see that taken in too great quantities, or too frequently, 

 may not only render it too thin, but also deficient in 

 quantity. 



Diuretic medicines are of much value in many 

 diseases. For example, in swellings of the legs the use 

 of diuretics have the effect of carrying off as we 

 have above shown a greater than ordinary quantity 

 of the watery portion of the blood. Nature has 

 always a tendency to keep in equilibrium all her 

 machinery and laws ; consequently, the absorbent 

 vessels are stimulated to greater action in order to 

 compensate for this waste, and take up and convey 

 into the circulation that portion of the fluid which had 

 affected the limbs. In short, many horses are so pre- 

 disposed to swelling of the limbs, that it is impossible 

 to render them fine without the use of diuretics. We 

 shall treat this part more fully in our chapter on 

 medicines ; but we may in the meantime offer the 

 following precautions in the use of diuretics. First, 

 let the horse have as much drink as he will take, as 

 this will promote the urinary evacuations. Secondly, 

 the stable should be kept cool, and the clothing thin ; 

 because, if this is not attended to, the medicine given 

 to stimulate the kidneys will pass off by perspiration, 

 and the effect intended will be thus frustrated. It 

 is a law of the animal economy that when the skin 



