Y: Hey, Don! I didn’t expect to see you at the park. Taking a walk?
D: Hey, Yaël. Yes—I thought Fido and I could use the fresh air. Oh, look! He’s so happy to see you that he’s wagging his tail. I wonder if he smelled your scent from far away. Did you know that dog’s noses can be tens of thousands of times more sensitive than ours?
Y: That’s not all Fido’s snout can do! A recent study suggests that dog’s noses can actually sense heat.
D: Uh, that doesn’t sound very surprising. Most mammals have furless, moist skin around their nostrils, called the rhinarium. This skin is sensitive, and filled with nerves. Though it’s worth noting that a dog’s rhinarium is colder than the rest of its body.
Y: As you say, a dog’s nose is special. Fido’s rhinarium can sense weak thermal radiation from a significant distance. In the study, researchers trained three pet dogs to choose between two covered, identical objects placed five feet away. The only difference between the objects was their temperature: one was room temp, and one was about eighty degrees. The researchers themselves had to touch the objects to know which was which. Most of the time, the dogs chose the warm object.
D: Eighty degrees? That’s not too far away from body temperature. Perhaps the heat sensitivity helped dogs’ ancestors hunt down prey.
Y: That’s the researchers’ hunch. They also took MRIs of thirteen dogs who were given warm or room temperature objects. With the warm objects, a specific region of the dogs’ brains was activated. But how does Fido’s brain make sense of thermal information? For now, only the nose knows.