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Emerg Med J. 2007 December; 24(12): 848–850.
PMCID: PMC2658361

Best Evidence Topic Reports

Weather dependent nasal erythema in reindeer (Rangifer tarandus)

Report by Stewart Teece and Bernard A Foëx, Santa's little helpers

Checked by Kevin Mackway‐Jones, Professor of all things jolly

Emergency Department, Manchester Royal Infirmary, UK

A short cut review was carried out to establish whether nasal erythema in a reindeer might be a useful navigational aid on Christmas Eve. From a search of nine papers, five presented evidence relevant to the question. The author, date and country of publication, “subjects” studied, study type, relevant outcomes, results and study weaknesses of these papers are presented in table 33.. The clinical bottom line is that a reindeer with a red nose at rest at the North Pole would not inspire confidence.

Table thumbnail
Table 3

Three part question

[During inclement weather, especially low temperature and fog] is [nasal erythema in reindeer (mythical or otherwise)] a [good indicator of fitness for 24 h transglobal navigation and travel]?

Clinical scenario

On Christmas Eve you intend to circumnavigate the globe stopping at every household containing a child in the space of one night using reindeer as your means of propulsion. However, it is a bit misty out and you fear this will make the task a little bit tricky: some sort of navigational aid would be helpful. You notice one of the reindeer has a very shiny red nose (you might even say it glows). All of the other reindeer are laughing and calling it names but you wonder whether this might be the answer to your navigational problems.

Search strategy

Medline 1950‐September 2007 using the OVID interface.(exp Reindeer/or rangifer OR AND [(exp nose/or exp rhinophyma/or exp rhinitis/OR (nose or rhinophyma or rhinitis).af. OR (snout or snotter or conk or neb or schnoz or hooter).af.)] no LIMITs.

Wikipedia: red‐nosed reindeer.

Search outcome

Nine papers were found from Medline. Five helped answer the three part question; the others helped wrap presents. Wikipedia revealed Rudolph's story, but was a bit short on the science of his red nose.


There appears to be no evidence for a specific disease state in reindeer, therefore nasal erythema may be due to increased blood flow to the nose. The differences in exhaled air temperatures at different ambient temperatures and the variations in total respiratory heat loss suggested the action of a nasal heat exchange mechanism. The papers by Johnsen et al (1985 and 1987) demonstrated the anatomical basis for the heat exchange mechanism. The study by Johnsen and Folkow (1988) suggested that the control of brain cooling is mediated by efferent sympathetic activity to the angular oculi and facial veins. During increasing heat stress cold venous return from the nose is switched from the facial veins to the angular oculi to effect preferential brain rather than body cooling. The distribution of adrenergic receptors means that for any change in sympathetic activity there are opposite effects on the two veins, allowing blood flow to be switched from one to the other.

It has been suggested, by Blix and Johnsen (1983), that in winter the nasal heat exchange mechanism restricts heat loss at rest, but, “in reindeer chased by wolves or tourists it serves as an important avenue of heat loss”.

The evidence suggests that in winter resting reindeer will not have a red nose, but that when frantically circumnavigating the globe their noses will glow as they try to lose heat. A reindeer with a red nose at rest at the North Pole means either deranged temperature regulation, or the use of drugs. Neither of these conditions would inspire confidence for an arduous journey.

Clinical bottom line

A global positioning system is perhaps a more reliable navigational instrument than a reindeer with a brain at boiling point.


  • Blix A S, Johnsen H K. Aspects of nasal heat exchange in resting reindeer. J Physiol 1983;340:445-54. [PubMed]
  • Langman V A. Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus). Respir Physiol 1985;59:279-87. [PubMed]
  • Johnsen H K, Blix A S, Jorgensen L. et al. Vascular basis for regulation of nasal heat exchange in reindeer. Am J Physiol 1985;249(5 Pt 2):R617-23. [PubMed]
  • Johnsen H K, Blix A S, Mercer J B. et al. Selective cooling of the brain in reindeer. Am J Physiol 1987;253(6 Pt 2):R848-53. [PubMed]
  • Johnsen H K, Folkow L P. Vascular control of brain cooling in reindeer. Am J Physiol 1988;254(5 Pt 2):R730-9. [PubMed]

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