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IACUC Considerations


Animal models are crucial to preclinical respiratory research as they help in improving the understanding of disease pathways and assessing potential therapies. Any activities that involve animals in research must first be approved by the International Animal Care and Use Committee (IACUC), who play a key role in ensuring the humane use and care of these animals.

The Principle Investigator (PI) and their staff are responsible for following the IACUC rules and regulations during experimentation.

preclinical COPD research

Main functions of IACUC include

  • Reviewing and approving protocols that will involve animals
  • Ensure that alternatives to potentially painful procedures were actively considered and a veterinarian was consulted in the study design process
  • Inspect the facilities and study areas every 6 months
  • Monitor the institutions program for humane care and use of animals
  • Investigate any concerns or complaints received
  • Suspend any activity involving animals that is not being conducted in accordance to the protocol approved by IACUC


There are federal policies and regulations that have specific requirements regarding review of proposed animal activities. This includes:

  • Public Health Service (PHS) Policy on Humane Care and Use of Laboratory Animals
  • US Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research and Training
  • US Animal Welfare Act and Animal Welfare Act Regulations (AWRs)

Note that the AAALAC accreditation has no regulatory authority but institutions can assure the PHS that they are complaint with the PHS policy.

What is IACUC looking for?

  • The objectives and potential value of the study
  • Reasoning for the selection of the animal model and the search for alternatives
  • Justification and minimization of animal usage
  • Description of experimental procedures
  • Pain and Distress, alternatives and refinement of protocol to reduce pain
  • Restraints
  • Estimation of post-operational pain and post-operational care
  • Endpoints and euthanasia
  • Training and qualifications of the PI and their staff
Animal Models for COPD
The objectives and potential value of the study

Provide a basic overview of the proposed study so that everyone on the committee can understand it, regardless of their level of scientific knowledge. This overview should also help them understand the societal implications of the proposed study. When writing the IACUC submission, it’s important to note that this section cannot be a summary of the aims listed in the grant application.

Researchers must also consider the potential value of the study and how it will contribute to the enhancement of human or animal health and the good of society. The potential benefits of the study should outweigh any pain, discomfort, or distress experienced by the animals.


Selection of an animal model and the search for alternatives

The PI must provide the reasoning behind their selected animal model. It is their responsibility to select the optimal species for the project with consideration of financial and housing restraints. Generally, monetary costs are not an adequate justification and should not be a significant factor in choosing an animal model. The rationale used should be scientifically based and relate back to the goal of the study. Essentially, the PI must prove to the reviewers that the animal model selected will address the hypothesis and research questions proposed. The PI should also explain why they didn’t choose an animal lower on the phylogenetic scale.

In this section of the IACUC submission, PIs should consider the three Rs: Replacement, reduction, and refinement.

  • Replacement: Scientific research on animals should only be carried out when all the nonanimal alternatives have been ruled out as an option. Researchers have an ethical obligation to explore options where animals can be partially or completely replaced (PHS Policy: U.S. Interagency Research Animal Committee Principle III). The four broad categories of alternatives include modification of existing use of animals, use of animal-derived material in place of whole animals, replacement of living systems with non-living ones, and use of mathematical or computer models.
  • Reduction: PIs should keep the number of animals required to a minimum while being consistent with sound scientific and statistical principles.
  • Refinement: PIs should refine their protocol to reduce the amount of pain, distress, or discomfort caused to the animal.
Minimization of animal usage and justification of animal numbers

This section is heavily scrutinized by IACUC as there is an ethical requirement to use the least number of animals possible. The experiment should be designed so that the most amount of info can come from the least number of animals while considering attrition. Additionally, the AWRs require proof that the new project is not duplicating previous studies to prevent unnecessary use of animals.

IACUC Considerations

A flow chart helps to explain the animal numbers. This is especially true if the study has a complicated breeding scheme or is a combination of several studies in one. The IACUC will specifically look for how the group sizes were determined, what statistical parameters and power calculations were used to achieve statistically valid results. If statistical analysis is not possible, the AWRs allow other methods such as published literature that used the same or similar animal models. For in vitro studies using animal tissue, the justification can be based on the amount of tissue or cells needed.

Breeding colonies should be the right size to provide enough animals for the experiment without producing too many extras that will be needlessly euthanized. Further, IACUC will want an explanation for any unwanted phenotypes created. The PI should include any other potential uses for unwanted genotypes, for example, they can be used for training staff or in a pilot study.

Researchers should investigate the possibility of sharing individual experimental animals or animal tissues between compatible research groups as long as the experiments are not inhumane or scientifically conflicting. Additionally, it may be useful to consult with experts regarding the statistical analysis required for animal numbers or any database searches to identify potential alternatives. This can be beneficial as it provides the IACUC with information they want from the start, saving time in the long run.

Description of experimental procedures

The description of experimental procedures must include all procedures that will be done. The layout of this section will vary depending on the IACUC, but it can include a flow chart or checklist of procedures.

The key here is to include the right amount of information. Too little information means that a proper review cannot be conducted. Too much information leaves little room for minor adjustments throughout the experiment and can result in a noncompliant event. Information on surgical or invasive procedures anesthetics and nonsurgical procedures should be included in this section.

A veterinarian must be consulted in the planning process of any procedures that could cause pain to the subjects such as surgeries. Surgical or invasive procedures should be described and defined as major or minor and survival or non-survival. Any pre-operative procedures and acclimation to devices used in or after surgery should be included as well.

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The name, class, and schedules of administration of any anesthetics, analgesics, sedatives, or tranquillizers used should be described. It is a good idea to include a range of dosage to allow for flexibility during the procedure. Note that many institutions may already have a preferred formulary of recommended anesthetics and analgesics developed by an attending veterinarian. If a PI prefers to use an anesthetic that is not on that list, it’s best to meet with the attending veterinarian to find an option that meets both the scientific needs and clinical recommendations.

A detailed sequential description of the surgical procedures is required. Any pre and post-surgical care must be in line with the established veterinarian and medical procedures. This includes information on the administration of substances, imaging procedures, behavioral tests, and prolonged physical restraints. For the administration of substances, the route, frequency, volume, and known toxicity of the substance should be included.

Pain and distress

A painful procedure is described as one that would result in animal pain if the analgesic drug was withheld. Many IACUCs use the USDAs pain and distress classification, which is used for USDA regulated species. It is imperative that the pain is eliminated or maximally reduced for all procedures. The AWRs also require the measures used during the literature search for alternatives to painful and distressful procedures. This includes the search strings used, date of the search, and time period covered.

Pain alleviation and reduction applies through the duration of the procedure and after the procedure until the pain is reduced to an acceptable tolerance level. Further, IACUC will expect PIs to use the most effective drug available. In the IACUC submission, researchers should include how their study design limits the pain, discomfort, and distress of any animals involved.



The use of physical restraints should be limited to awake animals and only be used after alternative procedures have been considered and found inadequate. If prolonged physical restraints are required, IACUC will want to know what the minimum duration necessary to achieve the research objectives. Additionally, the PI should describe the restraint, and measures such as acclimation used to reduce distress. Any time a restraint needs to be used; the animal should be acclimatized to the restraining device before the start of the experiment. The restraint should not be used on animals that show any behavioral or physiological stress.


Endpoints and euthanasia

If a PI feels that death is a required endpoint, it must be strongly justified in the submission. PIs should establish humane endpoint criteria for when euthanasia should be performed. The most desirable method for euthanasia is one that causes rapid unconsciousness, followed by cardiac or respiratory arrest. The method selected will depend on the species and weight of the animal involved. Generally, the method selection will follow these criteria:

  • Ability to cause death without causing pain
  • Time required to produce loss of consciousness
  • The time required to produce death
  • Reliability
  • Minimization of psychological distress
  • Compatibility with research requirements and purpose
  • Compatibility with histopathologic evaluation
  • Any hazard to personnel
Training and qualifications of the PI and their staff

IACUC will ask for the qualifications, experience, and training of everyone performing any of the protocols. The PI is responsible for the use of animals on the protocol and implementation of compliance with institutional rules, federal laws, and regulations.


Other relevant information to include
  • Non-standard housing and husbandry
  • Movement of animals into and out of housing facility
  • Species specific enrichment
  • Use of non-pharmaceutical grade substances
  • Hazardous agents
  • Biological materials

The submission process varies with the institution. The actual submission can be done online through a portal or a text document. After submission, there could be a pre-review process to ensure that all sections are completed, and all documents required are included. Many IACUCs will have a Veterinarian do the prereview to be sure that the procedures are properly described, appropriate drugs are being used, and intervention plans are addressed.

After the pre-review, the submission moves to the review process. The outcome of the review can include approval, requirement of modifications to secure approval, and approval withheld. In some cases, the IACUC will approve a submission as a pilot study. This happens when there are new procedures proposed. The approval is for a limited time on a small number of animals. Once the pilot study is reviewed, the PI can submit a protocol for the full study.

IACUC Considerations


  1. National Association for Biomedical Research (NABR) IACUC Functions
  2. Everything You Need to Know About Satisfying IACUC Protocol Requirements Swapna Mohan and Patricia L. Fole ßCan we have a link for this?
  3. University of Nebraska specific IACUC guidelines
  4. United States Department of Agriculture (USDA) IACUC protocol review resources
  5. American Association for Laboratory Animal Science (AALAS) IACUC Central