42 GENERAL THERAPEUTICS FOR VETERINARIANS 



brane by most of the cathartics, including calomel, aloes, rhubarb, 

 sulphur and especially the neutral salts. The latter operate in at 

 least three different ways. Proof of their stimulant action is 

 found in the fact that very dilute solutions, which could not gener- 

 ate an osmotic stream, produce diarrhoea. Radziejewski studied 

 experimentally the influence of cathartics upon peristalsis by 

 means of intestinal fistulae in dogs and found that the peristaltic 

 movements of the intestines and the flow of fluid through the 

 fistulae were considerably increased after the administration of 

 laxatives. Intestinal peristalsis may be stimulated reflexly from 

 the stomach by some drugs; croton oil, for example, will produce 

 diarrhoea while it is yet in the stomach. Acceleration of peri- 

 stalsis causes a more rapid discharge of the intestinal contents. On 

 account of the decreased absorption of the intestinal fluids, the 

 discharges are thin and fluid; they are the unchanged contents of 

 the small intestines. 



(d) Increased secretion of the intestinal glands with increase 

 of the intestinal fluids and acceleration of peristalsis. The most 

 important representatives of this group are arecoline and pilo- 

 carpine, specific gland stimulants. The neutral salts also stimu- 

 late the intestinal glands during their elimination from the blood, 

 thus making their action a four-fold combination. Intestinal 

 secretion is also stimulated reflexly by those drugs which irritate 

 the mucous membrane, especially the drastics. 



The intestinal fluids, including the secretions of the mucous 

 glands, Lieberktihn's and Bruner's glands, the pancreas and liver, 

 can only be increased in sufficient amount to produce diarrhoea 

 when the blood is rich in water. As Hay has pointed out, fluid 

 bowel discharges are not produced by the neutral salts, even in 

 large doses, when animals have been without water for several 

 days and have received only dry feed. This observation agrees 

 with the well-known experience of veterinarians that a horse or 

 cow which has received a cathartic must be permitted to drink a 

 large quantity of water in order to accelerate the action of the 

 drug and increase its effect. 



(e) Transudation and exudation of blood-serum as a cause of 



