114 GENERAL THERAPEUTICS FOR VETERINARIANS 



In normal conditions, all these factors are operating at nearly their 

 full functional capacity and for this reason, when diuretics are 

 administered to healthy animals, the secretion of urine is either not 

 increased at all, or only slightly or temporarily. On the other 

 hand, in diseases in which there is decreased activity of the gland 

 cells, low blood-pressure, poor blood supply or blood stasis in the 

 kidneys, or depression of the diffusion activity of the renal tissues, 

 the depressed secretion of urine may be increased by numerous 

 drugs. The diuretics operate in different ways, corresponding to 

 the complicated processes which are concerned in physiological 

 diuresis. According to their mode of action, the diuretics may be 

 divided into the following groups: 



1. Specific stimulants for the secreting renal epithelium: caf- 

 *feine, theobromine, theocine, diuretin, agurin, calomel, salicylic 

 acid, milk sugar and alkalies. The action of these diuretics is 

 independent of cardiac activity; they increase the secretion of 

 urine even when the blood-pressure is considerably depressed. 



2. Circulatory diuretics: digitalis and strophanthus. In con- 

 sequence of the increase of blood-pressure in the glomeruli of the 

 kidneys produced by these drugs there occurs, in a purely physical 

 manner, an increased filtration of blood-serum through the walls of 

 the glomeruH into the excretory uriniferous tubules. This group 

 of diuretics is most effective in diseases of the heart accompanied by 

 low blood-pressure. 



3. Stimulant diuretics (aeries) produce an active hyperaemia, 

 and in consequence an increased secretion of urine. This group 

 includes alcohol and a series of ethereal oils, resins and balsams: 

 turpentine oil, turpentine, juniper berries, oil of juniper, balsam of 

 Peru, balsam of copaiba, petroselinum (parsley), ononis, ligus- 

 ticum, mustard, black pepper, capsicum, colchicum, cantharides 

 and alcohol. 



4. Saline diuretics accelerate diffusion in the kidneys, in- 

 crease the water content of the blood and, at the same time, mildly 

 stimulate the renal epitheHum. They include: sodium chlo- 

 ride, sodium and potassium bicarbonate, sodium and potassium 

 nitrate, sodium and potassium acetate, potassium chlorate, 



