VETEBINARY MEDICINES 377 



classes depending upon the action they produce when introduced 

 into the body. The most commonly prescribed veterinary 

 medicines belong to one or more of the following classes: 



Anesthetics are agents which reduce sensation. They act 

 locally or generally, depending upon the kind of anesthesia 

 desired and the agent employed. Cocain and synthetic prepa- 

 rations of similar chemical composition are used to produce local 

 anesthesia by injecting a solution of the drug into the tissues. 

 Chloroform and ether are general anesthetics. They are admin- 

 istered through the respiratory tracts and act by deadening the 

 central nervous system. 



Antipyretics are agents which reduce fever by depressing the 

 circulation, diminishing oxidation, and promoting heat loss by 

 increasing radiation and conduction of heat from the body. 

 They are used to keep the fever within bounds, rather than for 

 dispelling it entirely. Examples are quinin, aconite, acetanilid. 



Antiseptics are agents which inhibit the growth of germs, but 

 are not strong enough to kill them or produce irritation to the 

 tissues. They are used for wound applications. Examples are 

 boracic acid, iodoform, tincture of iodin. 



Astringents are agents which contract tissues and check secre- 

 tions. They are used for wounds. Examples are alum, zinc 

 sulphate, tannic acid. 



Blisters are agents of an irritating nature applied to the skin 

 for the purpose of bringing more blood to the part and thus in- 

 creasing the activity of the underlying tissues. They cause 

 little vesicles or blisters containing a straw-colored fluid to form. 

 They are especially useful in chronic inflammatory conditions 

 such as bone and joint diseases. Examples are cantharides, 

 red iodid of mercury. 



Cathartics are agents used to evacuate the bowels. They 

 operate by stimulating peristalsis; by increasing the fluidity of 

 the intestines in causing the intestinal glands to pour out secre- 

 tions; by hindering absorption; by combining two or more of 

 these actions. They are used in a large number of diseases, e.g., 

 constipation, diarrhea, liver diseases, founder, congestion, and 

 dropsy. Cathartics should not be administered to very weak 

 animals, those in advanced pregnancy, or those suffering from 

 peritonitis. A cathartic producing a mild action is known as a 

 laxative; one producing drastic action as a purgative. There are 



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