Using Mice Facial Expressions to Help Detect Chronic Pain

Karen Lee Richards Health Guide
  • Did you know that mice show pain through facial expressions in the same way humans do?  While that's interesting, you're probably wondering how that knowledge could possibly help your pain.  Actually this new-found information could not only lead to better pain treatments for humans, but could improve veterinary care for your pets and improve conditions for lab animals as well.

    A new study, lead by McGill University Psychology Professor Dr. Jeffrey S. Mogil, discovered that when subjected to moderate pain stimuli, mice showed discomfort through facial expressions in the same way humans do.  The study, published in the journal Nature Methods, also details the development of a Mouse Grimace Scale that could help with better treatments for humans and improve conditions for lab animals.

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    According to Dr. Mogil, because pain research relies heavily on rodent models, an accurate measurement of pain is paramount in understanding the most pervasive and important symptom of chronic pain, namely spontaneous pain. 

    "The Mouse Grimace Scale provides a measurement system that will both accelerate the development of new analgesics for humans, but also eliminate unnecessary suffering of laboratory mice in biomedical research," says Mogil. "There are also serious implications for the improvement of veterinary care more generally."

    Developing the Mouse Grimace Scale

    This is the first time researchers have successfully developed a scale to measure spontaneous responses in animals that resemble human responses to those same painful states.

    Dr. Mogil and his associates analyzed images of mice before and during moderate pain stimuli - for example, the injection of dilute inflammatory substances, as are commonly used around the world for testing pain sensitivity in rodents. The level of pain studied could be comparable, researchers said, to a headache or the pain associated with an inflamed and swollen finger easily treated by common analgesics like Aspirin or Tylenol.

    The images were then sent to the lab of University of British Columbia Psycholgoy Professor Kenneth Craig where facial pain coding experts used them to develop the scale. They proposed that five facial features be scored according to the severity of the stimulus:

    • Orbital tightening (eye closing)
    • Nose bulge
    • Cheek bulges
    • Ear position
    • Whisker changes

    Craig's laboratory is a leader in studying facial expression as the standard for assessing pain in human infants and others with verbal communication limitations.

    Continuing experiments in the lab will investigate whether the scale works equally well in other species, whether analgesic drugs given to mice after surgical procedures work well at their commonly prescribed doses, and whether mice can respond to the facial pain cues of other mice.

    In My Opinion...

    I think this new study is fascinating.  I'm always happy to see any research that could help speed up the development of new effective ways to treat pain.  But as an animal lover, I'm particularly pleased that this new understanding can also lead to reducing pain for my pets and laboratory animals in general.

  • This study is just the latest of many important pain-related advances made by McGill University in Montreal, renowned for its historic contributions to pain research, including the internationally recognized McGill Pain Questionnaire, developed in 1975 and still the standard today, and the McGill Pain Scale, which identifies the pain levels of various chronic pain conditions.  Kudos to McGill and their researchers for their continuing work on our behalf! 

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    Langford DJ, et al. Coding of facial expressions of pain in the laboratory mouse. Nat Methods. 2010 May 9.
    How the Mouse Grimace Scale will help us cope with pain.  McGill University News Release. May 9, 2010.


Published On: May 12, 2010