Why Is Rudolph’s Nose So Bright?

Blood vessels explain why the most famous reindeer of all had a red nose

(RxWiki News) We sing about him at Christmas every year, but do you really know why Rudolph’s nose is so red? It turns out that reindeer have 25 percent more capillaries in their shnoz than humans.

A newly published observational study by Dutch and Norwegian scientists found that the nasal microcirculation of reindeer is richly vascularized—meaning, reindeer have a lot of red blood flowing through their noses.

"Keep your extremities protected to stay warm in cold weather."

Can Ince, PhD, at the Department of Intensive Care Medicine, Erasmus Medical Center, Erasmus University in Rotterdam, and his colleagues compared five healthy human volunteers, two adult reindeer, and a patient with advanced stage nasal polyps.

Using handheld video microscopes to examine the noses of all participants, scientists found that bloods vessel structures were denser in reindeer compared with humans. Investigators commented that these handheld microscopes “have also identified microcirculation as a key factor in a wide range of diseases, including diagnostic support and treatment responses in oncology.”

Thermal images also showed the reindeer nose to be red.

The researchers said that the increased blood flow in reindeer noses delivers more oxygen, controls temperature and helps against inflammation.

Superior microcirculation protects the animal from “freezing during sleigh rides and regulates the temperature of the reindeer’s brain, factors essential for flying reindeer pulling Santa Claus’s sleigh under extreme temperatures,” write the authors.

Investigators suspect that reindeer noses evolved to have more capillaries to keep their noses warm in frosty climates.

Reindeer participants also had a high density of mucous glands in their snouts, which “maintain an optimal nasal climate during changing weather conditions and extremes of temperature.”

John Cullen, PhD, research associate professor in the department of surgery at the University of Rochester Medical Center in New York, who was not an author of the study but reviewed the work, told dailyRx News, “The research shows the importance of having that surface blood flow to have that warm feeling.”

In an interesting side note, Professor Cullen said that the researchers applied a small amount of cocaine (100 mg) to the nasal membranes of one participant to evaluate vasoconstriction, or the narrowing of blood vessels. The drug is routinely used in ear, nose, and throat medicine as a local anesthetic and vasoconstrictor, according to the study.

“Scientists used the cocaine so they could see the reactivity of the human vessels,” said Professor Cullen. “They didn’t use it with the reindeer, thankfully, because we don’t want reindeer high on cocaine pulling Santa around in the sky—although the toys might get delivered a lot quicker.”

The study was published online in the December issue of the BMJ (British Medical Journal).

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Review Date: 
December 21, 2012