USDA Pain & Distress Categories
All vertebrate animals used in research, per federal regulations, must be designated an appropriate pain or distress category. The categories below describe each category and a few of the examples for each. If you are unsure as to which category to assign your animals, please contact the Attending Veterinarian or the IACUC Manager.
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Animals being held, bred, or conditioned for use in teaching, experiments, research or surgery, but not yet used for such purposes.
Examples:
- Animals on breeding protocols with no research or experimental component
- Animals acquired by the facility but held in quarantine or acclimation period prior to use
- Euthanizing animals on a holding protocol following current professional standards
- Observing animal behavior in their home enclosures without manipulation
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No more than momentary or slight pain or distress and no use of pain-relieving drugs, or no pain or distress. For example: euthanatized for tissues; just observed under normal conditions; positive reward projects; routine procedures; injections; and blood sampling.
Examples:
- Observing animal behavior in the lab
- Positive reward training or research
- Food restriction that reduces the animal’s weight by no more than 15 percent of normal age-matched controls
- Manipulative procedures such as weighing, injections, palpations, skin scrapings, and radiography
- Administering an anesthetic, analgesic or tranquilizing drug to an animal for restraint purposes to perform a procedure that involves no pain or distress such as imaging procedures
- Exposure to mild alteration in environmental conditions with appropriate acclimation
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Category D
Procedures that may cause pain or distress, but for which appropriate anesthetics, analgesics, or tranquilizers are used to minimize animal suffering. The key principle is that animals are provided with effective pain management to limit discomfort as much as possible throughout the procedure.
Examples:
- Surgical manipulations (survival or terminal) in which the animals received appropriate pre-, intra-, and post-operative anesthetics and analgesics
- Rodent retro-orbital bleeding conducted under anesthesia
- Terminal perfusions (euthanasia via blood removal) performed under deep anesthesia
- Tooth extraction performed in the field
- Using Freund’s complete adjuvant if alleviation of pain/distress occurs
- Tumor induction or implantation if alleviation of pain/distress occurs
- Induced infections or antibody production in which animals experience pain alleviated by analgesics
- Exsanguination under anesthesia
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Procedures that have accompanying pain or distress to the animals and for which the use of appropriate anesthetic, analgesic, or tranquilizing drugs would have adversely affected the procedures, results, or interpretation of the teaching, research, experiments, surgery, or tests.
Examples:
- Paralysis or immobilization of a conscious animal
- Any Category D procedure for which needed analgesics, tranquilizers,sedatives, or anesthetics are withheld for justifiable study purposes
- Toxicological, microbiological, or infectious disease research that requires continuation after clinical signs are evident without medical care or that requires death as an endpoint
- Food or water restriction which reduces the animal’s weight by more than 15 percent of normal age-matched controls
- Certain types of forced exercise protocols that could reasonably be expected to cause distress or exhaustion
- Applying noxious stimuli that the animal cannot avoid/escape
- Exposure to extreme environmental conditions
- Long-term restraint (days to weeks)
By law, the institution must annually report all category E procedures to the USDA and include a scientific justification supporting the IACUC’s decision to approve them.