An experiment has revealed that pain is contagious among mice.

Science Advances revealed that when mice are exposed to others that are distressed, they can smell pain and experience it as well even in the absence of illness or injury.

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Andrey Ryabinin and his research team did not originally plan to study pain transmission among mice. Their experiment was initially focused on understanding alcohol withdrawal effects on mice and how it can help people get over addiction. Alcohol withdrawal causes generalized and severe pain which pushes people to go back to their addiction.

However, they noticed that mice who were undergoing morphine or alcohol withdrawal and those given inflaming injections develop high sensitivity on their foot when poked.

To the surprise of the researchers, healthy mice also manifest pain sensitivity when exposed to distressed mice. Healthy mice will quickly pull its tails away from hot water and lick its paw after being injected with an irritating substance. In addition, mice placed on beddings used by distressed mice also show heightened sensitivity.

The study hypothesized that pain seemed to be transmitted through olfaction. Loren Martin of University of Toronto said that it is the first time research has shown that distress in one group of mice can be sensed and felt by another group.

The behavioral neuroscientists said that the implications for humans are not yet established since our olfactory skills are weaker compared to other animals.

It is also possible that the sense of hearing and sight may also affect mice's sensitivity to their fellows' pain. This supports existing statements that "rodents exchange information about their states in many exciting and complex ways."