Have you ever noticed that the tip of a dog’s snout is usually cold? This furless skin surface surrounding the nostrils is called the rhinarium. In land-living mammalian carnivores, the temperatures of the rhinaria tend to be cooler than those of other mammalian groups. This low-temperature, small surface area is typically highly sensitive to thermal radiation, or heat, and may be related to predation. Since domestic dogs have been living with humans for the past 15 centuries and don’t need to hunt anymore, can they still detect thermal radiation using the tips of their snouts? 

Professor Kröger and his team at Lund University set out to answer this question using a pair of complementary experiments. In a behavioral experiment, three dogs – Kevin, Delfi, and Charlie – were able to detect weak thermal stimulus 5 feet away that resembled the body temperature of potential prey, about 92℉. A fan blowing from the position of the dogs to the stimuli ruled out the possibility that they were reacting to the scent rather than the heat. Additionally, the team used magnetic resonance imaging (MRI) to study the brain activity of 13 pet dogs. Upon thermal stimulation, the dogs’ left somatosensory association cortex became active. This part of the brain co-registers different sensory information and plays an important role in planning goal-directed actions, including predating. This is further evidence of how sensing distant heat signals may play a role in dogs’ responses to their surroundings.

The sample sizes of these experiments were relatively small, but the coherency in findings suggests that domestic dogs may have the ability to sense weak thermal radiation using their nose-tips. Further studies are required to shed light on how rhinaria pass thermal radiation signals to the brain, and how this ability affects our furry friends’ day-to-day function. While many questions remain to be answered, next time when you get to ‘boop the snoot’ of a dog, you can tell your friends that the dog has likely received the warmth of your love.

Dr. Anna Bálint is a post-doctoral associate in the Department of Biology at Lund University. Dr. Ronald H.H. Kröger is a Professor in the Department of Biology at Lund University.

Managing Correspondent: Yuli Lily Hsieh

Press Article: Why do dogs have cold noses? Live Science. 

Original Journal Article: Dogs can sense weak thermal radiation. Scientific Reports. 

Image Credit: Creative Commons

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