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Guidelines for Reporting “Significant Changes” to Proposals for Vertebrate Animal Use


To clarify when it is necessary to report a change to an animal care and use protocol.


NIH guidelines and USDA regulations require that any significant change in a protocol that has previously been approved by the Institutional Animal Care and Use Committee (IACUC), be reported to and reviewed by the IACUC. This list is not exhaustive but is intended as a guide to the type of changes that the IACUC might regard as “significant changes” requiring IACUC approval.


Changes may be significant if they effect the animals used in the project in a positive or negative way. This may include but is not limited to changes in personnel, housing, numbers of animals, substitution of a different species, use of analgesics and anesthetics, surgical procedures, endpoints, etc. Examples are listed below.


Proposed significant changes to approved procedures should be submitted to the IACUC before they are instituted. If in doubt whether a proposed change is “significant” from the point of view of animal welfare, please call the one of the University lab animal veterinarians or the Chair of the IACUC.


The following are examples of changes in animal use procedures that could affect animal welfare and should be reviewed by the IACUC:

  • Change in procedures that will result in more than momentary or slight pain or distress.
  • Change in method of anesthesia, sedation or analgesia.
  • Change in protocol that would require animals to be fed, housed or cared for in a way that is not standard for that species, or does not meet that species’ minimum requirements.
  • Change in experimental protocol that would require more than momentary physical restraint of the conscious animal, e.g., chairing of primates, or use of other devices to physically restrain the subject while the
    experiment is in progress.
  • Change in protocol where death becomes the experimental end point. For purposes of this criterion, death is defined as natural death resulting from experimental conditions (rather than euthanasia at a time when a set of criteria recognized as the end point is met).
  • Change in protocol that would require an animal to undergo more than one survival surgery. Any addition of surgery to a protocol that did not previously including surgery.
  • Changes in method of euthanasia: e.g.,
    • from a chemical or inhalant method to a physical method
    • from any method to decapitation without anesthesia
    • from an AVMA recommended method to a method not specifically recommended.
  • Change of species.
  • Significant increase in number of animals used over that projected.