HANDLING OF KADIOLSOTOPES WITH ANIMALS AND PLANTS 1 1:3 



clamp a small-diameter catheter inside the stomach tube to carry the 

 activity and wash solution, thus decreasing surface area and adsorption. 

 The animal is restrained, the mouth spread, and the moistened tube 

 inserted gently over the back of the tongue and into the esophagus as the 

 animal swallows. A commercial mouth spreader is available for use with 

 swine and sheep. For cattle and horses a stomach-tube speculum can be 

 employed which keeps the animal from biting the tube and directs the 

 tube into the esophagus. With horses, the tube may also })e passed 

 through the nostril. After insertion it should be determined that the tube 

 is actually in the stomach and not in the lungs. Frequently the pa.ssage 

 of the tube through the esophagus can be directly observed. The animal 

 will usually cough if the tube has gone into the lungs. As an additional 

 criterion, the open end of the inserted tube can be placed underwater, and 

 bubbles will be seen if it is in the lungs. Upon assurance that the tube is 

 correctly located, a large syringe filled with wash solution is attached to 

 the open end, and the radioactive solution is injected into the lumen of the 

 stomach tube or insert. 



In general, for the farm animals, the capsule method offers an advan- 

 tage over the stomach tube. The stomach tube requires thorough wash- 

 ing to ensure quantitative delivery of the activity, and there is a greater 

 possibility of spread of contamination. The capsule can be used only 

 when the volume of the radioactive solution to be administered is com- 

 patible with the capsule size for the given animal. It is necessary to 

 prevent softening of the gelatin capsule between the time when the solu- 

 tion is placed therein and the time when the capsule is administered. 

 This may be done either by placing an inert absorbent such as filter paper 

 in the capsule prior to addition of the solution or by using two capsules, 

 the smaller containing the solution being placed within the larger. These 

 procedures will allow 5 to 10 min working time. 



The balling gun is customarily used for oral administration. It is con- 

 venient to place the capsule, ready to be loaded, in the gun and to add the 

 radioactivity by pipette. The cover can then be placed on the capsule 

 with tongs, and the gun handled directly with the gloved hand at a dis- 

 tance of 10 to 15 in. from the activity, which reduces exposure. In the 

 case of beta emitters the walls of the balling gun serve as an effective 

 shield. The mouth of the immobilized animal is opened, the balling gun 

 inserted, the capsule delivered in back of the tongue, the gun removed, 

 and the animal's mouth held closed until the capsule is swallowed. A 

 gamma emitter can be followed with a monitor to indicate when the cap- 

 sule has moved into the stomach. 



If an animal can be trained to consume completely a small amount of 

 feed, this offers a convenient method for oral administration. For exam- 

 ple, a hole can be drilled into a food pellet into which the radioactivity 



