378 PRINCIPLES OF VETERINARY SCIENCE 



three groups of cathartics, viz., saline, aromatic, and oleaginous 

 cathartics. 



The saline cathartics commonly used are magnesium sulphate 

 or Epsom salts, sodium chlorid W Glauber's salts, and magnesium 

 citrate. These agents have the power to produce an outpouring 

 of fluid from the intestinal walls into the bowels. They act only 

 when taken by way of the mouth. Their .mode of action is 

 not certain, but probably is due to the irritating effects of the 

 acid radicle combined with the metallic base. The cells in the 

 bowel walls react by pouring out a watery secretion to dilute 

 the irritant. This results in catharsis. The theory of osmosis 

 does not explain the action of saline cathartics for large doses of 

 sodium chlorid solution do not cause the reaction. 



The aromatic cathartics include aloes, cascara, and rhubarb. 

 These act when taken into the body through the mouth or in- 

 jected hypodermically. They cause irritation to the nerves of 

 the bowels which increases the bowel movements and results in 

 evacuation. 



The oleaginous cathartics include raw linseed oil, cottonseed 

 oil, and certain mineral and other oils. Their action is due to the 

 irritating effects of the soap which forms when the oil combines 

 with the bile in the intestines (hydrolysis) . A longer time must 

 be allowed for effects from this class of cathartics which are 

 particularly useful in emptying the posterior bowel. 



Caustics are agents which destroy tissue. They are used to 

 remove warts and to arrest the formation of proud flesh. Exam- 

 ples are copper sulphate, silver nitrate, butter of antimony. 



Disinfectants are agents which destroy germ life. They 

 are used on infected wounds, and on the skin when an operation 

 is to be performed. Examples are cresol, carbolic acid, coal 

 tar dips. 



Diuretics increase the excretion of urine by stimulating the 

 kidneys. They are used for diseases in which a -more profuse 

 flow of urine is desired. Examples are potassium nitrate, tur- 

 pentine, sweet spirits of nitre. 



Emetics produce vomiting through irritation to the nerves of 

 the stomach. Their greatest value is in connection with small 

 animals that have been poisoned. Mustard and warm water is a 

 homemade emetic. Apomorphin, a derivative of opium, is 

 frequently employed for this purpose, Tartar emetic is used 



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