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Most of us know that dogs have cold noses. Raise your hand if you haven't ever startled by your dog's cold impertinent nose contacting your skin when you least expected it!

While cold noses go hand-in-hand with dogs, we are missing important information such as why those doggy noses are cold in the first place. 

Recent research has revealed some interesting findings regarding a dog's cold and wet nose. Let's take a closer look at what science has to say!

Carnivores and Cold Noses 

According to research published in the Journal of Thermal Biology, noses are considerably cold in carnivores compared to the herbivorous counterparts. 

The study revealed that the skin on the noses of adult dogs, who were alert and comfortable, were colder than the surrounding temperature, measuring from 30°C (approximately 5°C colder) down to at about 15°C. 

It can therefore be said, that, the temperature on a dog's nose is normally a few degrees lower that the actual surrounding temperature, and we can say the same for other carnivores.  

This is in great contrast with the warmer noses of herbivores, which likely suggests that a carnivore's cold nose must have played some important adaptive role considering its functional, operating state. 

Did you know? The technical term for the hairless patch of skin surrounding the dog's nostrils, that we commonly refer to as "the nose," is rhinarium. 

A dog's rhinarium, with all its small domes and ridges, is unique in each dog, just as a human fingerprint. 

dog nose

A dog's rhinarium, with all its small domes and ridges, is unique in each dog, just as a human fingerprint.

Detection of Heat

A recent study has revealed that a dog's nose is sensitive to radiating heat. Through training, researchers found out that dogs can detect a warm object from a distance of approximately 1.6 meters.

This difference in temperature is so small that humans cannot detect it without touching it.

Even magnetic resonance scans revealed increased activity in the dog's left somatosensory association cortex, upon being presented with stimuli that were about  10.7 °C warmer than the surrounding ambient temperature at a distance of 240 mm. 

Closer scrutiny revealed how a dog's nose is blessed with a thin layer of stratum corneum skin allowing for closer, more direct contact with nerve receptors in the tissue so to ameloriate detection of temperature with no direct contact.

According to the research paper: "It is also of interest that the stratum corneum in dog rhinarium is thinner than one would expect. The thin stratum corneum layer might be advantageous when detecting stimuli not in direct physical contact with the skin, such as infrared radiation."

Courtesy of the dog's cold nose, such detection of heat must have played an important evolutionary role allowing dogs to detect infrared radiation from prey that are warm-blooded.

Did you know? While a dog's nose remains cooler than the surrounding temperature, if the outdoor temperature happens to freezing, that is–32°Fahrenheit or 0°Celsius,  – a dog's nose will remain around 46°F. 

Present From Birth

A dog's ability to detect heat is really nothing new, but no research has gone so much into detail. 

We already knew for some time that, not only can puppies smell at birth, but their noses also come equipped with special heat sensors.

Ever wondered how a newborn puppy can crawl back to mom? Momma's smell may play a role, but Yngve Zotterman, of the Swedish Research Council, actually discovered this fascinating perk.

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Where is the Stop on a Dog's Head?

If you're looking for the stop on a dog's head, you'll need to look at the head correctly and have a dog breed blessed with this feature.

Basically, these special heat sensors are located around those nostril slits and the opening to their nasal passages.

It has been found that these sensors are capable of detecting infrared energy that's radiated from warm objects.

Stanley Coren also talks about this in his book: "Why Does My Dog Act That Way?: A Complete Guide to Your Dog's Personality."

He claims: "Evolution has provided an additional source of sensory information to help the puppy at this critical time in the form of special heat sensors in his nose." 

Help Mother Dog Produce More Milk

Special heat sensors in a puppy's nose draw them to their mothers 

The Power of Wet Noses 

On top of being cold, another characteristic of a dog's nose is that it is often wet. Even such wetness is there for a purpose. 

Wet dog noses help dogs smell better because they secrete a thin layer of mucus and this moisture allows them to absorb scent chemicals from the air.

Researchers believe that a wet nose therefore is better capable of trapping scent molecules that drift inward, making them easier for dogs to analyze.

On top of this, consider that scent is water soluble. Dogs with cool, wet noses will do a better job of working with scent than those with dry noses, explains Vickie Lamb in the book: "The Ultimate Hunting Dog Reference Book."

Scent detecting conditions therefore tend to worsen when the air is hot and dry compared to when the air is damp and humid. 

Did you know? We are often led to believe that a wet nose is a sign of health and therefore assume that the presence of a dry nose in dogs means something is terribly wrong with our companions.

The truth is, the level of moisture of a dog's nose is not a reliable sign of health, just as our lips, dog noses tend to be more humid or less based on several factors such as how dry or humid the air is.

If your dog's nose, is excessively dry or crusty, this warrants a vet visit so to rule out several potential causes of a crusty nose in dogs.

The Power of Nose Licking 

Interestingly, when dogs lick their nose, it may just look to us as if they are just wiping it, but in reality there's likely more to it!

When your dog licks his nose, scent chemicals are being wiped off and when the tongue returns to the mouth, these scent chemicals are sent up the dog's incisive papilla which is located on the roof of the mouth.

This allows dogs to analyze the scent better as it reaches the Jacobson organ.

Also, now that the dog has wiped away the old scent, he is now ready for capturing fresher scent! How fascinating is that?

Discover More Interesting Facts About Dog Noses

References:

  • Kröger RHH, Goiricelaya AB. Rhinarium temperature dynamics in domestic dogs. J Therm Biol. 2017 Dec;7
  • Tuminaite, Inga & Kröger, Ronald. (2020). Rhinarium skin structure and epidermal innervation in selected mammals. Journal of Morphology. 282. 10.1002/jmor.21313. 
  • Bálint, A., Andics, A., Gácsi, M., Gábor, A., Czeibert, K., Luce, C. M., Miklósi, Á., & Kröger, R. H. H. (2020). Dogs can sense weak thermal radiation. Scientific Reports, 10(1), 1-9.  
  • Anna Bálint et al. Dogs can sense weak thermal radiation, Scientific Reports (2020).
  • Rhinarium skin structure and epidermal innervation in selected mammals
  • December 2020Journal of Morphology 282(2)
  • Why Does My Dog Act That Way?: A Complete Guide to Your Dog's Personality, By Stanley Coren Free Press; 1 Reprint edition (December 4, 2007)

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