174 



OPERATIVE TECHNIQUE. 



hobbles it is usually replaced by the use of a glass funnel and rubber 

 tube, which has the additional advantage of being very much cheaper 

 than the s3Tinge. 



In this case the needle is introduced as before and the funnel 

 attached to the end of the rubber tube which should be filled with, say, 

 warm normal salt solution, so that all air is excluded, and should 

 be closed with a pinch-cock for controlling the flow. 



One of the drawbacks of intravenous injection is the tendency to 

 thrombosis of the vein in consequence of injury 

 to the tunica intima by the needle. This danger, 

 however, as well as that of the entrance of air, can 

 be avoided by skilful manipulation. By proper 

 care in choosing the drug and carrying out the 

 above manipulation bad results are avoided. 



2. In subcutaneous or hypodermic injection, 

 which has largely replaced the above method, the 

 drug is injected by means of a syringe and hollow 

 needle into the loose connective tissue beneath 

 the skin. A graduated syringe holding about 2 

 to 4 fluid drachms is used and the injection made 

 at a spot clear of the harness and where the skin 

 is freely movable, /. e. where subcutaneous tissue 

 is abundant. The side of the neck, breast, behind 

 the elbow, and flank are convenient positions. 



Hypodermic solutions should as far as possible 

 be sterile and unirritating. The various alkaloids 

 are most useful. The syringe and needle should 

 be thoroughly clean and preferably sterilised by 

 boiling or by thoroughly washing out with 5 per 

 cent, carbolic or creolin solution. This precaution 

 is doubly necessary when the syringe has been 

 previously used for animals suffering from con- 

 tagious disease. Some operators also disinfect 

 the seat of injection, though this precaution is 

 perhaps scarcely necessary. 

 Raising a fold of skin with the thumb and index flnger of the left 

 hand the operator passes the needle either along the fold or at right 

 angles to it into the subcutaneous tissue. It occasionally happens that 

 a blood-vessel is penetrated, as shown by the escape of a few drops of 

 blood, and, under these circumstances, it might be dangerous to inject 

 insoluble substances like veratrin. In such case the needle is slightly 

 withdrawn, and if the bleeding ceases the syringe ma}- then be fitted to 



Fig. 198. — Double 

 acting syringe. 



