Ch. 6 — Alternatives to Animal Use in Research • 131 
animal behaves allows correlational inferences to 
be made, but not causal ones. If the experimental 
goal is to determine a particular brain area that 
is responsible for a certain behavior, that area must 
be manipulated directly. Electrical stimulation of 
brain areas is useful in establishing causal rela- 
tionships, and the most definitive and reliable re- 
sults are obtained when stimulation is used in con- 
junction with lesioning or ablation (20). 
Drug Administration 
In research on the behavioral effects of experi- 
mental or currently available drugs, animals are 
injected either intraperitoneally (within the body 
cavity), intravenously, intramuscularly, or intra- 
cranially (within the skull, via an implanted can- 
nula). Depending on whether the drug must be 
given repeatedly, the injection procedure can be 
stressful and may cause discomfort. Within the 
last decade alternative administration methods 
have been developed that may replace the need for 
multiple injections in some chronic drug treatment 
studies. Capsules of porous rubber (Silastic®, 
produced by Dow -Corning) implanted beneath the 
skin release a drug slowly into the animal’s body, 
and stress produced by repeated injections is 
avoided. The method produces minimal discom- 
fort and is well tolerated by animals (63). Small, 
implantable minipumps are also available to de- 
liver drugs for days or weeks. 
The use of aerosols has also been suggested (174); 
although this would seem to hold promise for al- 
leviating the stress of injections, it has drawbacks. 
For example, animals may differ greatly in their 
inhalation rates, and dispersal of the drug into the 
air prevents adequate control of drug dosage. 
Food Deprivation 
It is important to distinguish between the differ- 
ent methods of depriving animals of food and the 
reasons for using any method. In most cases, ani- 
mals are deprived of food to motivate them to per- 
form various tasks or behaviors for food reward. 
The nature of the subject’s performance of such 
tasks— and not the food deprivation— is the object 
of study. 
Food deprivation is typically applied one of two 
ways: Animals are deprived of food for a stand- 
ard period of time (e.g., 24 hours) prior to testing 
or they are maintained at some percentage of their 
normal body weight (e.g., 80 percent) (43). Each 
procedure has advantages and disadvantages. Food 
deprivation for specified intervals of time is easy 
to implement, but it fails to take into account spe- 
cies differences in metabolic rates. For example, 
24 hours of food deprivation for a mammal is less 
severe than it would be for a bird, while for a snake 
it would be inconsequential. Maintaining animals 
at a percentage of normal body weight avoids this 
problem, but it requires daily handling and the 
delay of the trial for long periods of time to stabi- 
lize body weights. 
When food deprivation is applied according to 
a standard time period in behavioral protocols , the 
most common interval is 24 hours (43). It is note- 
worthy that the feeding of domestic pets once a 
day parallels this laboratory protocol. When main- 
taining animals at some percentage of their normal 
body weight, behavioral protocols usually involve 
up to 20 percent weight loss (43). Experimental 
animals ’reduced food intake is associated in some 
instances with enhanced longevity (172). 
Several suggestions have been made to reduce, 
ameliorate, or eliminate food deprivation in be- 
havioral research: 
• Water deprivation, sometimes used concur- 
rently with food deprivation, should be used 
to motivate behavior only if thirst or drink- 
ing is the object of study. Water deprivation 
affects an animal’s physical condition more 
severely than food deprivation does , because 
death by dehydration occurs much more rap- 
idly than death by starvation (121). 
• The normal eating pattern of a species should 
be taken into account when deciding on the 
duration of food deprivation. For example, 
sparrows eat only during the light hours of 
the day; hamsters feed largely at night. 
• In some cases, food deprivation might be 
avoided bv using a highly preferred food as 
a reward (121). 
• Food deprivation mav also be avoided by tak- 
ing the experiment into the animal’s liv ing 
quarters, so that it is required to perform for 
