Anesthesia and Analgesia Recommendations

Federal guidelines, the Animal Welfare Act (AWA) and the Public Health Service Research Extension Act and the Guide for the Care and Use of Laboratory Animals (The Guide), require that procedures involving animals be conducted in a manner that avoids or minimizes discomfort, pain or distress. The Guide states:

The proper use of anesthetics, analgesics, and tranquilizers in research animals is an ethical and scientific imperative. The selection of the most appropriate analgesic or anesthetic should reflect professional judgment as to which best meet clinical and humane requirements without compromising the scientific aspects of the research protocol.”

If a painful procedure must be conducted without the use of an anesthetic, analgesic, or tranquilizer – because such use would defeat the purpose of an experiment – the procedure must be approved by the committee [IACUC] and supervised directly by the responsible investigator. Muscle relaxants or paralytic drugs (e.g., succinylcholine or other curariform drugs) are not anesthetics. They must not be used alone for surgical restraint, although they can be used in conjunction with drugs known to produce adequate analgesia.

The following sections provide detailed information regarding the IACUC recommendations for the use of analgesics and anesthetics as well recommendations for acceptable agents and dose ranges.

BU IACUC Approved October 2008; updated January 2014, July 2021, February 2022.

Standard of Care in Animal Pain Management

Animal anesthesia, analgesia and pain management are crucial components of research involving animal subjects. The standard of care at Boston University is to prevent animal pain as far as possible and to treat animal pain whenever diagnosed. Exceptions to these principals are permitted only in the minority of protocols approved by the Institutional Animal Care and Use Committee as USDA Category E with adequate scientific justification.

Multi-modal anesthetic and analgesic regimens combine drugs from a variety of classes. They are designed to maximize the desired effects while minimizing those undesirable side effects that occur with over-reliance on a single agent.

Animals must be acclimated to their surroundings for several days prior to major procedures. In all instances, animals must have been released from quarantine, or the acclimatization period as established by BU ASC must be completed.

The ideal anesthetic/analgesic regimen

  • Provides pre-emptive analgesia so that animal pain is already being treated as the general anesthetic is wearing off, to prevent sensitization (“ramp-up”) of pain sensory mechanisms, and to lower the overall amount of general anesthetic required for the procedure.
  • Provides a pre-procedural tranquilizer as appropriate for the species.
  • Includes the administration of an anticholinergic to protect cardiovascular function during anesthesia.
  • Is precisely titratable to assure that animals receive adequate anesthesia to block pain sensation, to produce unconsciousness, and to produce immobility without experiencing hemodynamic instability or life-threatening anesthetic overdoses.
  • Does not interfere with the study that the animals are on.
  • Does not result in excessive undesirable post-operative side-effects.
  • Does not cause pain or distress on induction or recovery.
  • Is compatible with available equipment and available medications.

Pre-emptive analgesia

To meet the first goal, BU ASC and IACUC advocate pre-emptive analgesia, using one or more of three drug classes 30 minutes prior to the start of surgery, or, if that is not practical, as soon as possible after the animal has been induced. The three main classes of injectable drugs are:

  • opioid analgesics (such as buprenorphine or morphine);
  • non-steroidal anti-inflammatory drugs (such as carprofen, meloxicam, ibuprofen);
  • local/regional anesthetics (lidocaine, bupivacaine, proparacaine).

Pre-emptive use enhances pain management during the immediate post-surgical period. The disadvantages of this approach are that they add a pre-anesthetic injection that may be distressful to the animals. To avoid this issue, it is acceptable to administer the pre-emptive analgesia as soon as the animal has been induced. By the time the animal is aseptically prepared and moved to the operating table or area (in the case of rodents) and the surgeon makes the first incision, the pre-emptive analgesic, if administered intravenously (IV) or intraperitoneally (IP), will have had time to take effect. Other possible drawbacks with the administration of pre-emptive analgesia is that anesthesia will be deepened and anesthetic doses may need to be reduced, anesthesia recovery may be delayed, and that some are controlled substances requiring special storage and record keeping.

Sedation prior to induction

Peri-anesthetic administration of anticholinergic

Precise titration

Application of ophthalmic ointment

Pre-anesthestic fasting

Drug dosing and frequency of administration

Safe and effective animal anesthesia

Anesthesia Considerations

In general, smaller animals have higher metabolic rates and frequently require higher doses at more frequent intervals to achieve the desired effect. Species, strain and age differences often overshadow this general principle however. It is always best to start with a drug regimen developed in the species, age and strain with which the Principal Investigator is working, rather than extrapolate from one species to another. Also, when starting to use a new species or strain of animal, it is safer to administer the lower end of the dose range of parenteral anesthetics and analgesics. More can then be administered as needed. Safety and efficacy should thus be demonstrated in a pilot group of animals before a large-scale study is initiated.

Note that all of the doses listed in the individual species’ formularies at the bottom of this page are approximations and must be titrated to the animal’s strain, age, sex and individual responses. Significant departures from these doses should be discussed with a veterinarian. Doses will also vary depending on what other drugs are being administered concurrently.

All doses are listed as milligrams per kilogram (mg/kg) unless otherwise noted. Where a dose has not been determined, it is listed as TBD (To Be Determined).

Dilution of injected drugs allows more precise dosing, may make some drugs less irritating when injected, and may facilitate absorption, but also may shorten the shelf-life of the compound. Aseptic procedures must be observed as mixtures (cocktails) are prepared; this includes wiping the cover of each vial or bottle with 70% ethanol or isopropanol, diluting with sterile water or sterile saline and not reusing needles used for dilution or administration.

Only new, sterile needles must be used for withdrawing aliquots from the cocktail. Diluted drugs must be labeled with the contents and concentration of the dilution, the preparer’s name or initials, and dated, then discarded after 1 month, at the expiration date of any of the components, or according to the manufacturer’s instructions (whichever comes first).

Species-specific Considerations


Small Rodents: Mice, Rats, Hamsters, Gerbils

Guinea Pigs, Chinchillas




Nonhuman Primates





Commonly Used Anesthetics and Analgesics



Dissociatives (ketamine, tiletamine)

Alpha-2 Agonists (xylazine, dexmedetomidine)

Alpha-2 Antagonists (atipamezole)




Tribromoethanol (Avertin)


Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Local Anesthetics (Lidocaine and Bupivacaine)


Formularies (in alphabetical order)


Cat Formulary

Chinchilla Formulary

Ferret Formulary

Gerbil Formulary

Hamster Formulary

Mouse Formulary

Nonhuman Primate Formulary

Rabbit Formulary

Rat Formulary

Swine Formulary

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