Your dog's cold wet nose may help it 'see' in infrared

Researchers have discovered that the cold, wet skin at the tip of a dog's nose works as an infrared sensor which can detect weak thermal radiation.

"Something that you just know and accept, like the wet cold nose of the dog, you never actually think of what it could be used for," lead author Anna Bálint told Quirks & Quarks host Bob McDonald. "When you see it, it's pretty amazing."

The idea came from her colleague Ronald Kröger, professor at the Mammalian Rhinarium Research Group at Lund University. In a previous study, he had shown that carnivore noses tended to be colder than the noses of other mammals. That led the team to wonder if that served any actual purpose when it came to hunting prey.

"Usually the low tissue temperature impairs sensory activity, but there is one known exception and that is thermal reception," said Bálint, now a postdoctoral researcher at Eötvös Loránd University in Hungary. "In some species such as pit vipers this lower temperature may actually improve their their ability to strike accurately. And so this gave the idea that this cold nose may be actually used in dogs for something."

Getting insight from the dog's brains

First, the team did behavioural tests at Lund University. They trained three dogs to choose the warmer of two objects that were otherwise identical in size and scent. Sure enough, all three dogs were able to pick out the object that was 10 degrees warmer than the other, from a distance of 1.6 metres.

Then, in Hungary, Bálint worked with the Family Dog Project, which had already trained dogs to lie still in fMRI machines.

"They had dogs who were trained to lie motionless but were awake inside the scanner, and this was crucial for us. If you want to test some kind of sensory ability, you have to have animals that are awake inside the scanner," said Bálint.

With each of the 13 dogs, the team again had them looking at objects that looked the same and smelled the same, but with one slightly warmer than the other. This time, they looked at areas of the brain that responded to this stimuli.

"We found that there was a cortical region in the left hemisphere — but only in the left hemisphere — that actually showed higher activation when when this warm object was it was in front of them," said Bálint. "In many species it has been shown that the left hemisphere is related to predatory activity like food related actions. So that's why this was really interesting."

Infrared sensors with cold, wet nose technology

This is just the beginning of the research for Bálint, who still has many more questions she'd like to answer. "The whole purpose of this study as a first approach was to just establish some the existence of the sense," she said. 

Considering that other carnivores have cold, wet noses as well, next she wants to see if they, too, can detect thermal radiation. She also wants to understand more about how this sense works in the nose, to maybe help create better bio-inspired infrared detectors.

"It would be really important to figure out how this works, because if we figure out how it works, as in many many cases biology gives ideas to engineering," she said. "Biologically inspired technical innovations are so widespread then, why not? Why not here?"

The research was published in the journal Scientific Reports.

Produced and written by Amanda Buckiewicz