SUBCUTy\NEOUS INJECTION 13 



danger, however, in giving irritant drugs by this method, especially 

 chloral, and several cases of foreign-body pneumonia have come under 

 our notice as the result of this mode of administration. It is a method of 

 benumbing or killing the parasites (S. filaria and micrurus) infesting the 

 trachea and bronchi, and has been employed to influence the mucous mem- 

 brane of the larynx and trachea in certain inflammatory conditions. 



5. Drwgs are usually given hy the mouth and are absorbed from 

 the stomach and intestines. Many non-irritating and not unpleasant 

 drugs are taken voluntarily in the food, gruel, milk or drinking water by 

 animals. Cats and dogs will often swallow medicine enclosed in a piece 

 of meat. ^ Absorption is more tardy than by the subcutaneous method, 

 more rapid when given in solution into an empty stomach than when 

 administered in powder, pill or ball, and on a full stomach. Some drugs 

 are probably absorbed from the stomach, only to be destroyed or stored 

 in the liver (alkaloids and heavy metals), and do not enter the general 

 circulation at all. 



When drugs are administered for their local action on the stomach, 

 in catarrh or ulcer, they should be given a half hour to an hour before 

 feeding; if given for their action in or on the intestines, they should be 

 administered two or three hours after meals. 



6. Rectal injections of medicines (enemata or clysters) are prac- 

 tised when the use of drugs by the mouth is inadvisable or impossible, as 

 in unconsciousness, dysphagia, convulsions; also to destroy parasites 

 (pinworms) in the rectum, to influence an inflamed or ulcerated rectal 

 mucous membrane, and to remove intestinal contents (oil and glycerin). 



The dose of drugs by this method is generally twice that by the 

 mouth, and absorption is slower and more imperfect. The drug should 

 he non-irritating, soluble, and not too bulky, since a small amount is nec- 

 essary (3i-§i dogs; 3ii-§viii horses); to avoid tenesmus and expulsion. 

 Warm starch solution (made by boiling) or linseed tea with a little 

 laudanum is a good vehicle for medicinal enemata, and retention of ene- 

 mata is facilitated by pressure on the anus with a towel for some minutes 

 after the injection is given. 



Solids are sometimes employed by rectum in suppositories. For 

 general use of enemata (see p. 27). 



7. Drugs are absorbed very slightly by the skin, and then only 

 when rubbed very vigorously into the epidermis (inunction) with lanolin, 

 fat or oil of some kind. Mercury, silver and iodine are most commonly 

 employed for absorption, but drugs are usually applied externally for 

 their local action only and not to influence the general system through 

 the blood. 



Intramammary injections. — These are useful in acute parenchyma- 

 tous mastitis. The injection is done with a Davidson syringe connected 

 with a sterile milking tube. From one quarter to one pint is injected 

 slowly into each teat and allowed to remain fifteen minutes and slowly 

 withdrawn. The treatment is given twice daily in contagious mastitis 

 and but once in the simple form. 



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