Ch. 5— The Use of Animals in Research • 105 
Table 5-3.— Classification of Research Experiments and Procedures 
According to the Degree of Pain or Distress for the Animal 
Level of 
pain/distress 
Examples of types of experiments 
Examples of procedures 
Absent or 
negligible 
• Noninvasive behavioral testing 
• Studies of migration or homing 
• Dietary preference studies 
• Banding for identification or tracking 
• Field observation 
• Fecal examination 
• Conditioned learning with food reward 
Low 
• Determination of pain threshold 
• Manipulation of blood chemistry 
• Experiments carried out on anesthetized 
animals that do not wake up again 
• Flinch or jump response 
• Injections 
• Tube feeding 
• Tattooing 
• Administration of anesthetic 
• Surgery under deep anesthesia and subsequent 
sacrifice 
—Removal of organs for histological or biochemical 
investigation 
—Culture of surviving organs 
• Blood sampling 
Moderate 
• Behavioral study of flight or avoidance 
reactions 
• Operations carried out under anesthesia or 
analgesia, with the animal waking up or 
experiencing the cessation of the action of 
the painkiller (postoperative pain) 
• Stimulation of unanesthetized animal 
• Biopsies 
• Implantation of chronic catheters 
• Castration 
• Mild electric shock 
• Implantation of electrodes 
• Central nervous system lesions 
• Exposure of internal organs 
• Food or water restriction for more than 24 hours 
High 
• Chronic stress studies 
• Drug withdrawal studies 
• Studies of certain infectious agents 
• Experiments on mechanisms of pain in 
conscious animals 
• Experiments on mechanisms of healing 
• Studies of radiation toxicity 
• Prolonged physical restraint 
• Chronic sleep deprivation 
• Intense electric shock 
• Production of pain clearly beyond threshold tolerance 
• Induction of burns or wounds 
• Surgery on conscious animal 
SOURCE: Office of Technology Assessment. 
ative anatomy, physiology, and pathology; and by 
basing inferences on subjective responses to pain 
experiences by humans. Careful attempts to esti- 
mate and categorize the degree of pain experi- 
enced by laboratory animals— ranging from ab- 
sent or negligible to high— can provide a basis for 
efforts to minimize the pain or distress caused 
by research procedures. 
ANIMAL AND NONANIMAL PROTOCOLS IN BIOMEDICAL AND 
BEHAVIORAL RESEARCH REPORTS 
One way to measure the balance of animal and 
nonanimal methods in research is to survey the 
end-product of experimentation— the published 
literature. OTA examined approximately 6,000 re- 
search reports published from 1980 through 1983 
in an effort to document the prevalence of ani- 
mal and nonanimal protocols in contemporary re- 
search. 
Fifteen leading scientific journals were selected 
to represent disciplines within biomedical and be- 
havioral research. These journals were chosen be- 
