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I. Purpose

The purpose of this policy is to define analgesic use for procedures that are expected to cause more than momentary pain or distress for animals involved in research activities at Montana State University. 

II. Definitions

Pre-operative: Occurring prior to the initiation of a procedure or surgery 

Peri-operative: During the period of time a procedure or surgery is taking place 

Post-operative: Relating to or denoting the period of time after a procedure or surgery has taken place 

III. Background

Pain usually results from stimuli that damage tissue or have the potential to damage tissue. Unrelieved pain can lead to unacceptable levels of stress and distress in animals, resulting in spurious or inconsistent experimental results. Pain can be difficult to detect in many animals since it is disadvantageous for non-human animal species to display signs of pain due to natural selection by predators, and humans may not recognize subtle changes in behavior indicative of pain. 

Federal regulations in the U.S. Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training state that minimization of discomfort, distress, and pain when consistent with sound scientific practices is imperative. Unless the contrary is established, investigators should consider that procedures that cause pain or distress in human beings may cause pain or distress in other animals. Furthermore, the National Institutes of Health state that procedures that may cause more than momentary or slight pain or distress to the animals will be performed with appropriate sedation, analgesia, or anesthesia, unless the procedure is justified for scientific reasons in writing by the investigator. 

IV. Policy

Unless there is a scientific reason to the contrary and approval has been granted by the Montana State University Institutional Animal Care and Use Committee (IACUC), investigators must administer analgesics for procedures associated with more than momentary or slight pain in animals. 

The IACUC acknowledges that procedures for administering analgesics may be better developed for some species than others, and that each type of analgesic may have a different efficacy in the alleviation of different kinds of pain. The alleviation of pain and distress is often a multifaceted task that may require pharmacologic interventions, adjustments to environmental enrichment, modifications to research protocols, and other appropriate and humane strategies. When establishing analgesic plans, pre-emptive analgesics should be used and multi-modal analgesia should be utilized whenever possible, such as combinations of local anesthetics and systemic medications that utilize different analgesic pathways. 

Indications for Use: 

Surgical or other procedures that cause pain in humans should be expected to cause pain in animals. The following considerations should be used when developing appropriate pre-operative, peri-operative, and post-operative analgesic plans. 

1. Invasiveness of the procedure: 

Are body cavities exposed?

Are especially sensitive tissues involved, such as weight-bearing bones, joints, or teeth?

Isthere significant tissue manipulation or inflammation?

Is there substantial impairment of physical or physiologic functions? 

2. Degree of severity of pain expected: 

How painful is a similar procedure in humans?

Whatis the behavior of the animal during the post-operative period? 

Superior pain control is usually provided when analgesics are administered preemptively. Some anesthetic regimens include agents with intrinsic analgesic properties, such as ketamine and xylazine in combinations commonly used in rodents. Other anesthetic agents such as inhalant anesthetics do not provide analgesia and must be used in conjunction with an appropriate analgesic when a painful procedure is performed. 

Some form of analgesia must be present prior to recovery from anesthesia following procedures that are expected to cause more than momentary pain or distress. This requires consideration of the pharmacokinetic onset of action of the selected analgesic or analgesics, defined as the interval between administration and establishment of blood concentrations associated with analgesic efficacy. 

For example, in most species, buprenorphine requires approximately 30 minutes following administration to reach therapeutic blood concentrations. Therefore, buprenorphine should be administered at least 30 minutes prior to recovery from anesthesia. In many cases, this is accomplished by administering the analgesic prior to or at the beginning of the painful procedure. 

In some situations, administration of certain analgesics prior to anesthetic recovery may complicate recovery by potentiating respiratory depression associated with the primary anesthetic. In these cases, immediate short-term analgesia may be provided through administration of a local anesthetic at the incision site and or administration of a nonsteroidal anti-inflammatory drug prior to surgery. 

Administration of analgesics should follow a multi-modal approach whenever possible. Local anesthetics such as lidocaine and bupivacaine are commonly used and generally have minimal side effects. In addition to local anesthetics, opioids and nonsteroidal anti-inflammatory drugs may be used in combination for procedures expected to result in severe pain, or individually for less painful procedures. All potentially painful procedures must include post-procedural monitoring within the approved protocol to assess evidence of pain that is not adequately controlled by the approved analgesic regimen. In all cases, analgesics must be administered if signs of pain are observed.

 V. References

Guide for the Care and Use of Laboratory Animals (8th Ed.) (PDF), published 2011. 

NIH, 2020 . Guidelines for Pain and Distress in Laboratory Animals: Responsibilities, Recognition and Intervention.. Animal Research Advisory Committee, Office of Animal Care and Use, NIH. Available at Guidelines for Pain and Distress in Laboratory Animals: Responsibilities, Recognition, and Intervention (PDF) 

USDA, 1997b. APHIS Policy #3, “Veterinary Care” (July 17). Available at Animal Welfare Act (PDF);  

 

 

IACUC Approval Date: 1/21/2026

Review Date: 1/21/2026

Issue Date: 1/26/2026