126 RADIOISOTOPES IN BIOLOGY AND AGRICULTURE 



PROCEDURES WITH ANIMALS 



To obtain meaningful results from animal experimentation, it is well 

 recognized that normal healthy subjects must be used and must be main- 

 tained in this condition for the duration of the stlld3^ It may not be so 

 apparent that in many types of investigation the animal should be con- 

 ditioned to the handling it is to receive. For example, frequently we see 

 experiments where rats that have been raised in lots in an air-conditioned 

 colony room are fasted for a short time, excessively handled prior to and 

 during the administration of the radioisotopes, and placed in a different 

 type of individual cage in a different environment for the study. Do 

 these animals eat and react normally, especially during the time immedi- 

 ately after dosage when the major metabolic handling of the isotope may 

 be taking place? 



These uncertainties can be minimized by taking the time and effort to 

 condition the animal properly. For at least 2 to 3 weeks before the exper- 

 iment, the laboratory animal should be kept in a cage similar to that 

 which is to be used, and should be handled in the same way that will be 

 necessary during the experiment. When farm animals are brought in 

 from the pasture for study, they likewise should be accustomed to han- 

 dling in the lot and be trained to the metabolism stanchion; this may 

 require one to several months. With dogs, there is always the controver- 

 sial issue of runs vs. cages. Certainly the dog confined to a cage for a 

 long period of time differs physiologically from the dog allowed to exercise. 

 Unfortunately, most radioisotope work has to be done in a metabolism 

 cage on account of contamination problems, whereas it is usually most 

 convenient to keep the dogs in outside runs. The management in this 

 case w^ll largely depend on the specific study, particularly as to cage space 

 available and as to how soon the excretion falls low enough to permit 

 return of the aiiimal to the run. 



Needless to say, it is most helpful if the animals are handled by men 

 who understand and sincerely like them. The scientist has a moral obli- 

 gation to practice the highest degree of humaneness with respect to 

 experimental animals. Such endeavors automatically improve the reli- 

 ability of the results obtained. 



The Small -animal Colony. In small-animal w^ork a most important 

 factor in regard to the suitability of experimental animals will be the 

 maintenance of environmental conditions so as to minimize infection, 

 disease, epidemics, and physiological changes. Discussion of biological 

 and dietary causes of variation is Ijeyond the scope of this text. The 

 management of animals until such time as they are treated Avith radio- 

 isotopes is no different from that in any conventional colony, as detailed 

 in general references (11 to 14, 16). However, a brief summary of man- 



