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Weather dependent nasal erythema in rangifer tarandus

Three Part Question

[During inclement weather particularly low temperature and fog] is [nasal erythema in reindeer (mythical or otherwise)] a [good indicator of fitness for 24 hour transglobal navigation/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 a dozen reindeer as your means of propulsion. However it is a bit misty out and you feel this will make performing this task a little bit tricky and feel 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 may be the answer to your navigational problems.

Search Strategy

Medline 1950-09/2007 using the OVID interface.
Wikipedia: red-nosed reindeer
(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

Search Outcome

9 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.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Langman VA,
Reindeer exposed to variety of temperatures between -5.5 and 27.2CObservational StudyTemperature of exhaled air at an ambient temp<10C.

Metabolic rates
Exhaled air 21C less than body temperature.

At the lowest ambient temperature 75% of the heat added to the inspired air was recovered by the nasal counter-current heat exchange.
No evidence reindeer expected to eat approx 1 billion carrots in next 24 hours.
Johnsen and Folkow,
7 winter-insulated adult female reindeer. In vitro studies of angular oculi and facial veins of adult reindeer.Observational studies.Blood pressure in the angular oculi and facial veins.During severe heat stress dorsal nasal vein BP increased in response to clamping the angular oculi vein.
Pharmacological stimulation of sections of facial vein and angular oculi veins.Facial veins lack á-adrenergic receptors, angular oculi veins lack â-adrenergic receptors.
Blix AS, and Johnsen HK.
2 adult female reindeer in a climatic chamber exposed to ambient temperatures ranging from -50 to +30C in winter and summer fur.Observational studyExhaled air temperature, rectal temperature, minute ventilation, total respiratory heat loss (trhl).Exhaled air temperature 20-22C below body temperature at lowest ambient temperatures, exponential increase in minute ventilation with ambient temperature in winter, trhl was lowest at lowest ambient temperatures.
Johnsen et al,
Resin casts of reindeer nasal vascular architecture. 3 adult Norwegian reindeer trained to run on a treadmill in a climatic chamber.Observational studiesAnatomic and histological examination of the reindeer nose vasculature.Reindeer have a parallel arrangement of communicating arterial and venous rete in the turbinates, which would act as a heat exchange mechanism.
Nasal mucosa temperature and expired air temperature.Optimization of heat loss from mucosal surfaces during heat stress with cold venous effluent directed to the cavernous sinus for brain cooling.
Johnsen et al,
Cineangiography of venous return in 3 adult reindeer subjected to either local or whole body thermal stimulationObservational StudyBlood flowSuperficial veins of the nose constricted during cold stress.

During heat stress selective cooling of the brain by cold blood from the nasal mucosa.
Probably the same 3 reindeer used in their previous study. They may have started to get fed up with all this.


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.

Level of Evidence

Level 3 - Small numbers of small studies or great heterogeneity or very different population.


  1. Langman VA. Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus). Respiration Physiology 1985;59(3):279-87.
  2. Johnson HK, Folkow LP. Vascular control of brain cooling in reindeer. American Journal of Physiology 1988;254(5 Pt 2):R730-9.
  3. Blix AS, and Johnsen HK. Aspects of nasal heat exchange in resting reindeer. J. Physiol 1983;340:445-454.
  4. Johnsen HK, Blix AS, Jorgensen L, Mercer JB. Vascular basis for regulation of nasal heat exchange in reindeer. American Journal of Physiology 1985;249(5 Pt 2):R617-623.
  5. Johnsen HK, Blix AS, Mercer JB, Bolz K-D. Selective cooling of the brain in reindeer. American Journal of Physiology 1987;253(6 Pt 2):R848-853.