134 The Diseases of Animals 
action of the drug is much more rapid and certain. 
Much smaller quantities of medicine are required to pro- 
duce given effects than when given by the mouth. 
Medicines to be given hypodermically should be suf- 
ficiently diluted, so that they will not injure the tissues 
nor cause severe pain. They must be free from sedi- 
ment and germs. The hollow needle of the syringe 
should be unserewed and taken in the right hand; the 
skin in the region of the neck or shoulder is firmly 
grasped with the left, and with the right the needle is 
quickly pushed through it in a slanting direction. 
Considerable force is required to push the needle 
through the skin of the larger and older animals, but 
the lack of resistance determines when the point is 
through. The syringe is then screwed on the needle and 
the medicine gradually injected. The medicine is injected 
into the loose tissue beneath the skin, usually in the 
region of the neck or shoulder, to avoid injury to the 
operator by the animal’s kicking or biting. For special 
purposes, medicines may be injected into almost any 
part of the body. 
In giving medicines hypodermically it is important 
that the instrument be perfectly clean and that the 
medicine be pure and well diluted. Under some con- 
ditions, medicine may be injected into the trachea, or 
windpipe, by inserting the needle between the rings of 
cartilage of which this tube is composed. It should 
be given in this manner only upon the advice of well- 
qualified persons. In inserting the needle, care should 
always be taken not to inject the medicine into veins 
or arteries, nor to puncture delicate structures. 
