CLASSIFICATION OF DIURETICS 125 



owing, it is believed, to stimulation of the vaso-motor 

 centre which controls the renal arteries. 



The proportion of the several urinary constituents is 

 altered by different conditions. Urea, uric acid, and 

 hippuric acid are increased by nitrogenous food, by 

 common salt, phosphoric acid, leucin, and glycocoll, and are 

 also augmented during the early stages of most acute 

 diseases. The percentage is diminished by alcohol, turpen- 

 tine, arsenic, and large draughts of water. Horses at rest 

 pass a maximum of uric acid and a minimum of the less 

 perfectly oxidised hippuric acid, but these proportions are 

 reversed during and immediately after exertion, when dis- 

 integration of proteid tissues freely uses up oxygen and 

 increases production of carbonic acid. 



Albumin is always a pathological constituent of urine, but 

 occurs in convalescence from febrile disorders, temporarily in 

 horses receiving excess of albuminoids, and also in hsemo- 

 globinuria in horses, and red water in cattle. It appears 

 especially in inflammatory conditions of the kidney ; and is 

 likewise produced by full doses of cantharides, which drug 

 also causes haematuria. Such exudation of albumin, more 

 apt to appear suddenly and temporarily in horses than in 

 man, is lessened by careful dieting, the animal only receiving 

 easily digested low diet or even milk alone, and by arbutin, 

 the active principle of uva ursi, and also by keeping the 

 bowels and skin in proper action, clothing the patient 

 comfortably, but avoiding active diuretics. Bile constitu- 

 ents are occasionally found in the urine of the lower animals, 

 but sugar is rarely present. 



Diuretics may be classified as follows : 



1. Saline diuretics, such as potassium acetate and nitrate, 

 liquor ammonii acetatis, the alkalies, saline infusions. All 

 these induce a condition of hydraamia, i.e. of excess of fluid in 

 the blood, and this excess the kidneys promptly endeavour 

 to remove. Thus the tissues are drained of fluid and this 

 action is particularly useful in cases of dropsy and the like. 



2. Drugs which act by increasing the blood flow through 

 the kidneys. Of these there are two groups, (a) consisting of 

 drugs which, whilst they do not lower general blood pressure, 

 yet dilate the renal vessels, examples being caffeine and the 



