Approved 07-17-14

Federal Animal Welfare Regulations (CFR Ch.1, 2.36(b) (5-7) require that USDA registered research facilities report an annual census of regulated animals used in research and teaching, the species used, and the number of animals placed in each of the four “Categories of Pain and Distress” (B,C, D and E). As a means of meeting this requirement and providing consistency of IACUC review, the NCSU IACUC requires that pain and distress category information be provided by investigators when they submit an application. The intent of this page is to provide general recommendations and guidance on how to assign animals to the different categories of potential pain and/or distress.

When completing the protocol form, assign each animal species listed to one of the following categories: B, C, D or E. List each animal under the highest pain/distress category that will apply to the animal at any time while on the protocol. You are not required to include non-research related veterinary care in determining the category of use. Please note that the severity or duration of the pain or distress, or the use of anesthesia or analgesia to alleviate pain or distress may result in animals being placed in different categories.


Pain and Distress Categories (B, C, D and E) with possible examples

Category B

Animals being bred, conditioned, or held for use in teaching, testing, experiments, research, or surgery but not yet used for such purposes.

Category C

Animal use activities that involve no more than momentary or slight pain or distress (no greater than an injection) where there is no need for use of pain-relieving drugs.

Category D

Animal use activities that involve accompanying pain or distress to the animals and for which appropriate anesthetics, analgesics, tranquilizing drugs, and/or humane endpoints are used to avoid pain, distress, or discomfort.

Category E

Animal use activities that involve accompanying pain or distress to the animals and for which appropriate anesthetic, analgesic, tranquilizing drugs; or other methods for relieving pain or distress are NOT used. Category E research, testing, or procedures will require strong scientific justification as to why pain-relieving drugs or other methods for relieving pain cannot be used on animals. This includes citation(s) to published studies if applicable, describing what alternatives were considered and how alternatives will be used whenever possible, clarifying whether animals will be euthanized when moribund, and if not, what information is to be gained in the interval between moribundity and death.

Guidelines for determining USDA classification in protocols involving antibody production

Neither the use of adjuvants (such as Freund’s) nor creation of ascites is automatically classified as Category E. This is dependent on the specific methods and agents used and, in the case of ascites production, the condition of the animal at first collection, and the number and frequency of collections.