Mice display human-like expressions in pain--study

Researchers from McGill University, Montreal, Canada, found that during pain, mice show facial expressions like eyes squeezing or inflating nose.

The Age quoted lead researcher, Dr. Jeffrey Mogil, McGill University as saying, “Considering the pain field’s heavy and continuing dependence on rodent models and the paucity of usable measures of spontaneous pain in animals, the ability to reliably and accurately detect pain, in real time, using facial expression, might offer a unique and powerful scientific tool in addition to having obvious benefits for veterinary medicine.”

Study details
Researchers conducted study on laboratory mice to determine if their facial expressions changed with pain.

For the experiment, certain pain-inducing substances like acetic acid, mustard oil and capsaicin (an active component of chili peppers) were injected in mice’s stomach and paws.

Then researchers used an intensity-scale called ‘mouse grimace scale’ (MGS) to measure facial expressions of mice.

Analysis revealed that mice showed discomfort through facial expressions similar to humans. Researchers found five prominent facial expressions the mice showed during intense pain, eye squeezing, nose bulging, cheek bulging, ears drawn apart and whiskers standing on end.

Furthermore, photographs helped assess mice’s pain with 80 percent precision, which went up to 97 percent in high-resolution visuals.

Scientific American quoted study-collaborator and psychologist Kenneth Craig, University of British Columbia in Vancouver, as saying, “This is the first study that has examined facial expressions of pain in non-human animals.”

Another experiment
Researchers, in another study, genetically altered a species of mice by mutation, which resulted in migraines in humans.

When mice were injected with inflammatory-substance, they displayed facial expressions akin to humans that normalized with pain-relieving drugs.

This gave more evidence that mice showed human-like expressions in pain.

Argument
Veterinary adviser, Dr. Ned Buyukmihci, British Union for the Abolition of Vivisection (BUAV) expressed his disbelief regarding the nature of experiment and was quoted by Times Online as saying, “These mice were subjected to atrociously painful situations without the benefit of any pain relief.”

“This study was not intended to improve or positively impact on the welfare of mice...rather just to find a new way of determining if a mouse is showing pain,” added Buyukmihci.

Lars Arendt-Nielsen, pain expert, Aalborg University, Denmark, dissuaded the findings by saying that they missed emotions like fear and questioned if the scale will apply to other animals.

The study appears in the journal ‘Nature Methods.’