Study: Mice Can Sense, Feel Each Other’s Pains with a Whiff

What hurts a single mouse can hurt every mouse in the immediate vicinity. That's the conclusion of a latest study that examined the social transfer of pain in mice, carried out by scientists at Oregon Health & Sciences University in Portland. The experiment, published on Science Advances, show that pain can move from one animal to the other without any illness or injury required. When a particular group of mice was given a painful stimulus, another group that was completely unaffected exhibited the same kind of increased sensitivity at first.

Andrey Ryabinin, neuroscientist at Oregon Health & Sciences University in Portland, and his team didn't initially set out to examine the transfer of pain. However, they noticed something interesting while conducting experiments on mice that were made to undergo the process of alcohol withdrawal. During this procedure, mice have an increased sensitivity to pokes on their foot. Surprisingly, this was also apparent in their ideally healthy cage mates. There was some transfer of pain from the injured mouse to the bystanders, according to Raybinin.

When mice undergo morphine withdrawal and alcohol withdrawal or suffer from an inflaming injection, they get additionally sensitive to a poke in their paw. In this case, the bystander mice that were present in the same cage displayed other signs of increased pain sensitivity like licking a paw following an irritating shot or pulling out their tails from hot water.

The scientists then decided to cage the mice in a different room and repeat the original experiment. It was found that mice caged in the same room had approximately 68 percent increased pain sensitivity compared with those caged in a different room.

Further experiments revealed that the contagion of pain seems to spread through the nose. The team is now trying to find out compounds that carry this pain from one mouse to the other. These findings are not necessarily applicable in the case of human beings, but there is a growing body of evidence that indicates that people also feel the pain of others.