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Addressing Inadequate Pain Relief for Animals Used in Laboratories

Written by Kati Bertrand
September 2023

A white rat with staples in their head

Untreated or mistreated pain in laboratory animals raises significant scientific and ethical concerns in biomedical research. International animal welfare laws and guidelines have been established to minimize pain in animals, but adequate pain relief is often withheld from laboratory animals or, if it’s provided, it’s often poorly reported, which results in compromised welfare, lower-quality data, and reduced reproducibility.

There are several reasons why pain in laboratory animals is often left untreated or poorly managed. One common concern is that analgesics may interfere with experimental results. Researchers worry that pain relief could mask potential physiological or behavioral responses that are relevant to their studies. Improper post-procedural monitoring and care by laboratory staff also contribute to inadequate pain relief, which can cause suffering and compromise the well-being of exploited animals.

Studies and reports have shed light on the inadequate pain relief provided to laboratory animals. For example, a study by Herrmann and Flecknell in 2018 found that out of 684 proposed experimental surgeries, 30% didn’t require post-operative analgesia and an additional 10% provided analgesia only if deemed necessary, which indicates an extremely concerning failure to provide pain relief for laboratory animals.

Furthermore, as reported by Roe, Taylor, and Chandna in 2021, mismanaged pain relief and monitoring constitute a concerning percentage (> 50%) of welfare violations in a representative sample of laboratories in the U.S. These findings underscore the urgent need for improvement in pain-management practices.

Providing comprehensive pain relief for laboratory animals is challenging. Current pain-assessment tools are often indirect, unidimensional, and subjective. They require significant time and extensive training to apply accurately. Moreover, these tools often fail to address context-specific effects, pain masking in animals, species-specific needs, individual variations, and pain sensitization. Meeting these challenges requires the development of improved pain-assessment methods that offer a more holistic approach to the issue.

Pain-management procedures also often go unpublished. In a 2022 review of over 200 in vivo experiments, researchers found the following:

  • 87% didn’t mention pain monitoring
  • 68% didn’t report pre-surgical analgesia
  • 94% didn’t detail intraoperative analgesics
  • 64% didn’t report post-operative pain medication

Failure to report pain-relief methods and their effectiveness not only raises ethical concerns but also masks potential confounds in the data that can limit reproducibility. A study published in Comparative Medicine highlighted this issue.

The current state of pain relief provided to laboratory animals is far from satisfactory, because it raises serious ethical issues and hinders the reproducibility of studies. As Hanno Würbel, a professor of animal welfare at the University of Bern, emphasized in 2018, “there is huge scope for improvement”—including a pressing need to address the problem of sloppily conducted animal research whose results fail to hold up in studies of humans.

Inadequate pain relief in laboratory animals remains a significant concern, affecting both animal welfare and the reliability of scientific research. Addressing this issue requires a comprehensive approach that prioritizes the ethical treatment of animals.