Dr. Raj Subaraman, a noted neurophysiologist, recently moved his lab to Great Eastern University and submitted a protocol using the spared nerve injury model to the Great Eastern IACUC. Subaraman proposed to anesthetize his rats and then expose the sciatic nerve at the point where it trifurcated into the tibial, common peroneal and caudal sural nerves. The first two nerves were transected but the sural nerve was left intact. Subaraman's research team had done the procedure many hundreds of times previously, and he was able to assure the IACUC that there would be no motor dysfunction in the operated limb. By that he meant that the rat would be able to walk and groom normally and also gain weight normally. In fact, during the first postoperative week, abnormalities (such as increased sensitivity to heat or cold) were found only when specific neurological tests were carried out.

Based on his past experience, Subaraman knew that about one week after surgery, some animals would begin to show clinical signs of neuropathy (nerve degeneration, often with associated pain), and so he routinely began his experimental treatments—the crux of his research—four days after surgery. When the treatments were successful, neuropathy and pain were quite minimal and transient. However, when the Great Eastern IACUC finally approved Subaraman's protocol, it was with the condition that all of the operated animals would be placed in USDA pain or distress category E (unalleviated pain or distress). Great Eastern University, like many other schools, used the USDA's pain and distress categories even though it was not required to do so. At Subaraman's former institution, rats that had undergone surgery but had no (or very minimal) motor dysfunction at any time were placed in category D (alleviated pain or distress) as a consequence of the required surgical intervention. Only those animals that developed clinically apparent neuropathy were retroactively placed in category E. Subaraman thought that was fair, but the Great Eastern IACUC said that because the specific neurological tests were able to detect hypersensitivity to heat or cold during the first few postoperative days, there was a reasonable potential for pain or distress to be present on a continuous or near continuous basis. Although Subaraman argued, it was to no avail. The IACUC would not budge.

What is your opinion? Should all of Subaraman's rats be placed in category E, even though increased pain sensitivity is recognized only when the condition is artificially provoked by cold or heat, or is it more appropriate to have clinically normal animals in category D and only those with clinical neuropathy in category E?

Response to Protocol Review Scenario: Much ado about nothing!

Response to Protocol Review Scenario: Oversensitive IACUC

Response to Protocol Review Scenario: Actual pain vs. potential for pain