110 PRECAUTIONS IN THE USE OF CATHARTICS 



into the blood, or subcutaneously. The amount of fluid 

 secreted has been measured by Sir Lauder Brunton, who 

 experimented on cats with concentrated solutions of Epsom 

 salt tied into a loop of intestine. In four hours he found 

 that from 42 to 56 minims of serous fluid were outpoured 

 for every inch of surface acted on. In cattle or horses 

 upwards of 12 square feet of intestine must often be directly 

 stimulated by even a moderate dose of physic. A secretion 

 of 50 minims to the inch would give a discharge of nine 

 pints of fluid. Such considerations illustrate the depura- 

 tive and febrifuge effects of an active cathartic. 



The intestines of the horse are voluminous, presenting 

 about 550 square feet of vascular mucous membrane. 

 Purgatives and other irritants hence require to be used with 

 much caution. For a day previous to the exhibition of a 

 purgative, the animal, if possible, should be restricted to 

 mash diet or green food. The dose should be moderate, and 

 its effect may be accelerated and increased by administering 

 it while the animal is fasting, by occasional gentle exercise, 

 until it begins to operate, and by the repeated use of clysters. 

 This last auxiliary, when properly employed with sufficient 

 perseverance, is indeed so effectual in promoting the action 

 of the bowels that one of the most successful of army 

 veterinarians was wont to trust almost entirely to its use, 

 seldom giving, except in extraordinary cases, any purgative 

 medicine whatever. In serious, obstinate impaction of the 

 large intestines, a flexible tube, six feet long, should be 

 screwed on to a Read's pump, and copious enemata intro- 

 duced into the colon. 



For horses, aloes is the best cathartic. Linseed and castor 

 oils are tolerably good, but less certain ; while croton is 

 much too drastic, unless in small amount, and largely mixed 

 with some bland oil. Salines in cathartic doses are irregular, 

 and sometimes act with unexpected violence. Senna, colo- 

 cynth, buckthorn, and other drugs used as purgatives for 

 men and dogs have little effect on horses. 



With a warm mash the previous night, and subsequent 

 abstinence from solid food, a moderate dose of aloes given in 

 the morning, assisted by further mashes and occasional 

 draughts of tepid water, purges most horses in ten or twelve 



