HANDLING OF KADIOISOTOPES WITH ANIMALS AND PLANTS 



145 



a tight-fitting box. An ear vein can also be used satisfactorily in young 

 pigs. The dog, under restraint, may be injected in the jugular or 

 saphenous vein. There is also a lingual vein underneath the tongue 

 which may be used for injection when the animal is under anesthesia. 



With small animals, which can be completely immobilized, the direct 

 insertion of the needle into the vein is satisfactory. With larger animals, 

 however, this method is made difficult because a slight movement of the 

 animal may cause the needle to go through the wall of the vein or be pulled 

 out of the vein. There is no way of knowing just when this may occur. 



Fig. 4-20. Intravenous injection of solution into femoral vein of rat. (Courtesy of 

 U. S. G. Kuhn III and W. E. Lolz.) 



In such case an unknown portion of the radioactivity may be delivered in 

 the tissues external to the vein. To avoid this possibility, the technique 

 of venous catheterization can be employed. This technique has been 

 widely used for man and animals (17), and suitable catheter tubing is 

 available from surgical supply houses. The usual procedure is to insert 

 the needle into the vein and then to thread at least several inches of the 

 catheter tubing through it. The needle is then withdrawn. The cath- 

 eter is immediately washed out with heparinized normal saline (4 mg of 

 heparin per 100 ml of saline). The radioactive solution is then delivered 

 in the usual way through the catheter. The catheter may be left in place 

 for several days; however, under such conditions there is a strong probabil- 



