Cold Nose, Warm Sense

Cold Nose, Warm Sense

Did you know that your dog has something in common with vampire bats, pit vipers, and black fire beetles? What could that possibly be?

It all started when some scientists from Sweden and Hungary went into a bar…

Well, that might not be exactly true. I’m not sure where they were when they got together and asked the question: “Why is a dog’s nose moist and cold, when most other mammals’ noses are warm and dry?” No doubt this is a question that has also kept you awake many a night…

At first, they considered that the cold, wet canine nose might help with cooling in hot weather. But they discarded that idea because the surface area of the nose is just too small to make much of a difference.

They knew that under the skin of the dog’s rhinarium, the area of the nose surrounding the nostrils, there is a dense network of nerve fibers that connect to the trigeminal nerve, the largest nerve in the head. They wondered what information all those nerves under the skin of the nose might be sending to the brain.

At first, they considered that the cold, wet canine nose might help with cooling in hot weather. But they discarded that idea because the surface area of the nose is just too small to make much of a difference.

A Clue from Snakes

Being interested in all things animal, the scientists knew that pit vipers, such as rattlesnakes, have so-called pit organs on the sides of their faces that are wet and colder than the snake’s skin. They help the snake sense differences in temperature, just like a thermal imaging camera. They are so sensitive that they can detect differences of as little as 1/1000 of a degree. With the help of the pit organ, even in the dark, a snake can locate the warmth of a nearby rodent (Figure 1) so that it can strike its prey more accurately.

Dogs’ noses are wet and colder than the rest of their bodies, as seen by a heat-sensing camera (Figure 2). The scientists wondered whether those noses help dogs sense temperature differences just like in snakes.

The Experiments

To test this, the scientists in Sweden trained three dogs of a variety of sizes and breeds to obtain a food reward if they pushed a warm sliding panel. The dogs did not receive a reward if they pushed a neutral temperature panel. They then tested the dogs in a double-blind study (in which neither the dog nor the handler knew which panel was warm), and showed that the dogs were consistently able to detect the warmer panel with very high accuracy.

Next, the scientists in Hungary took over. They took 13 dogs that were trained to lie still in an fMRI unit and presented them with either a warm or a neutral temperature box. They then checked the fMRI images to see which part of the dogs’ brains were processing that information.

When the dogs were presented with a neutral temperature box, their brains showed no activity. However, when presented with a warm box, a discrete area on the left side of the brain lit up, indicating that warmth was being processed in that area. As it happens, that area of the brain is where many other kinds of sensory information are processed so that the animal can plan specific, targeted movements. The most likely reason for these movements is to capture prey.

These studies demonstrated for the first time that dogs really do have a sixth sense—that of being able to detect weak infrared radiation (heat). The only other species currently known to be able to sense infrared radiation are the black fire beetle, certain snake species, and one other species of mammal so far, the vampire bat.

The Take-Home Message

How might the ability to sense heat be important to us? This heat-sensing ability might just be what helps newborn puppies find mom’s warm nipples. It might also help bitches locate their puppies in low-lighting situations, and perhaps it also helps them realize when one of their puppies has passed away.

This sense is likely used by dogs participating in the sports of Barn Hunt and Earthdog in which dogs must search and find a living rat. Although the sense of smell will also be used, this ability to sense radiant heat might help dogs hone in on their prey faster, particularly terriers searching in dark, underground Earthdog tunnels.

It is likely that the sense is also used by hunting dogs, particularly the pointers, setters, and spaniels, which must locate and point out live, and therefore warm, gamebirds while hunting over large tracts of land.

With this new information, the amazing canine nose becomes the newest canine superpower.

These studies demonstrated for the first time that dogs really do have a sixth sense—that of being able to detect weak infrared radiation (heat). The only other species currently known to be able to sense infrared radiation are the black fire beetle, certain snake species, and one other species of mammal so far, the vampire bat.