20 



INTRODUCTORY 



dose is small. Drugs administered iii this way act promptly and 

 energetically. The alkaloid or active principle of the drug is 

 commonly used. A fold of the skin is picked up with the fingers 

 and tlie needle is quickly introduced, care being taken not to 

 prick or scratch the muscular tissue, as this causes some pain and 

 makes the animal restless. In order to avoid abscess formation 

 at the point of injection, the skin should be cleansed with a disin- 

 fectant and the syringe and needle sterilized before using. 



Drugs are not absorbed through the unbroken skin, but when 

 applied with friction, or when the outer layer is removed by 



Fio. 7. — Hypodermic syringes. 



blistering, absorption may take place. Liniments, blisters and 

 poultices are the preparations used. 



Volatile drugs, such as chloroform and ether, are absorbed 

 quickly by the enormous vascular surface of the lungs. This 

 class of drugs is administered for the purpose of producing 

 general anaesthesia. Ancpsthetics are indispensable in many 

 surgical operations. 



The administration of a drug in the form of medicated steam 

 is quite useful in combating some respiratory diseases. In 

 steaming large animals a pail about half full of boiling-hot water 

 to which has been added about an ounce of coal-tar disinfectant, 



