Controversy surrounds study where mice are made to suffer pain

Montreal - A lot of questions were raised after mice were purposely subjected to various methods of pain during a study at McGill University in Montreal. Researchers claim inducing pain on the animals is key to understanding pain responses.

The study was done to observe and photograph the expressions of mice in pain. “Researchers caused pain they characterized as "moderate" to "severe" to unanesthetized mice,” reported the Principal Investigators Association, a non-profit organization. “They observed and photographed the facial grimaces of the rodents as the animals responded to the pain. The aim was to develop a system for coding the severity of pain the mice felt through assessing the various facial grimaces the animals made in response to painful stimuli of varied intensity.” To cause pain the researchers immersed the animals’ tails in hot water, used radiant heat on them, attached a binder clip to their tails, injected irritants (mustard oil, formalin, zymosan) into their feet, induced bladder inflammation with a chemical that causes painful cystitis in humans, and injected acetic acid (causing the mice to develop abdominal constriction and writhe). They performed surgery on the mice, and left them without postoperative pain killers. During this, the mice were photographed. Criticism of the study was published in a U.S. newsletter called Laboratory Animal Welfare Compliance, which is published by the Principal Investigators Association. Leslie Norins, the publisher of the newsletter, questioned the research methods. "Mice were purposefully subjected to intense pain without anesthesia," CBC News quoted him as saying. "In our reading of the national guidelines, this came very close to a violation." The Canadian Council on Animal Care, which regulates the use of laboratory animals, investigated and made a ruling on July 22, that the study complied with Canadian ethical guidelines for animal research. Jeffrey Mogil, who led the study, told CBC that "To study pain, we need to produce pain — there's simply no way around it." Norins said he thinks the study deals with subject matter that is already well-understood, and that it seemed frivolous. The Principal Investigators Association web site explained that the “researchers concluded that a mouse grimace scale could be constructed from five facial grimaces characteristic of animals feeling moderate and severe pain. These were: orbital tightening, nose bulge, cheek bulge, ear position change, and whisker change.” The Canadian Council on Animal Care said that the results of the study might be useful as a tool to assess mouse welfare and make it easier to intervene early in cases where mice are put in situations where they could experience pain. They did not explain the ethics behind causing pain to animals in order to be able to intervene when pain was being caused to other animals.