Running reindeer are able to cool their brains

A Norwegian study that had reindeer running on treadmills has shown that the Arctic animals are able to selectively cool their brains.

The thick-coated mammals, which are heavily insulated against freezing temperatures, were found to use varying methods when they begin to overheat.

The scientists from the Universities of Tromso and Oslo measured the physiological responses of the creatures after teaching them to run on treadmills in cold temperatures.”Reindeer are the best animals to work with; once they trust the trainer they will do anything for you,” Prof Arnoldus Blix told the journal of Experimental Biology.

The researchers found that in the first stages of exercise, the reindeer simply heightened their breathing rate, causing an increase of blood flow to the nose. The hard-working animals, which are unable to sweat like humans, then moved on to panting, exposing their large wet tongues to the cool air to release their heat through evaporation.

“They do not have sweat glands like us humans which would ruin the [insulating] properties of their fur, but make use of the same principle – heat dissipation through evaporation of water – when they pant,” Prof Lars Folklow from the University of Tromso told BBC Nature.

Finally, the clever creatures used “selective brain cooling”, diverting the cold blood from their noses to their brains when they reached a critical temperature of 39°C.

“This high-arctic [animal] which tolerates cold very well, also has an immense capacity to tolerate heat stress due to the high efficiency of the panting mechanism and the habit of resorting to brain cooling when the heat load gets really high,” said Prof Folklow.