References

USDA AWA Regulations And Standards, Section 2.36 (B)7: Reporting Category E Animals

USDA AWA Regulations and Standards, Section 2.36 (b)7: 
“The annual report shall:…

State the common names and the numbers of animals upon which teaching, experiments, research, surgery, or tests were conducted involving accompanying pain or distress to the animals and for which the use of appropriate anesthetic, analgesic, or tranquilizing drugs would have adversely affected the procedures, results, or interpretation of the teaching, research, experiments, surgery, or tests. An explanation of the procedures producing pain or distress in these animals and the reasons such drugs were not used shall be attached to the annual report;“

http://www.access.gpo.gov/nara/cfr/waisidx/9cfr2.html