Although they have been our domestic companions for thousands of years and have been the subject of numerous studies, dogs continue to surprise scientists. This is particularly the case with their sense of smell, whose sophistication and efficiency are no longer to be demonstrated today. And recently, researchers have discovered that dogs’ noses are able to detect weak thermal radiation. A capacity shared by very rare animals.
The dogs’s noses continue to amaze scientists. Not only is it up to 100 million times more sensitive than ours, but it can also detect weak thermal radiation (body heat from mammalian prey), new study published in journal says. Scientific Reports. The discovery helps explain how dogs with vision, hearing and smell problems can still successfully hunt.
” It’s a fascinating discovery. It opens a new window on the sensory world of the highly evolved nose of dogs “Said Marc Bekoff, ethologist and expert in canine sniffing and professor emeritus at the University of Colorado. The ability to detect low, radiant heat is only known in a handful of animals (all of which they use to hunt prey): black beetles, some snakes, and one species of mammal, the common vampire bat .
Dogs: their rhinarium is able to detect heat
Most mammals have bare, smooth skin around the tips of their nostrils around their nostrils, an area called the rhinarium. But the dogs’ rhinarium is humid, colder than room temperature, and has many nerves, which suggests an ability to detect not only smell, but also heat.
Thermography of a dog, carried out at an ambient temperature of 27 ° C. The image shows a much colder nose than the rest of the body. Credits: Anna Bálint et al. 2020
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To test this idea, researchers from Lund University and Eötvös Loránd University trained three companion dogs to choose between a hot object (31 ° C) and an object at room temperature, each placed within 1.6 meters. The dogs were not able to see or feel a difference between these objects. (The researchers could only detect the difference by touching the surfaces).
After training, the dogs were tested for competence in double-blind experiments; all three successfully detected objects emitting weak thermal radiation.
A brain area dedicated to thermal detection
Next, the researchers scanned the brains of 13 companion dogs of different breeds using functional magnetic resonance imaging, while presenting the dogs with objects emitting neutral or weak thermal radiation. The left somatosensory cortex in the brain of dogs, which analyzes nasal signals, was more sensitive to hot thermal stimulus than neutral.
CT scan obtained from a dog’s fMRI showing activity in the left somatosensory cortex when thermal radiation is detected. Credits: Anna Bálint et al. 2020
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On the same subject : The strong smell of dogs helps them to perceive the world around them
The researchers identified a group of 14 voxels (3D pixels) in this region of the dog’s left hemisphere, but found none of these groups in the right, and none in response to the neutral stimulus. Together, the two experiments show that dogs, like vampire bats, can detect weak spots and that a specific region of their brain is activated by this infrared radiation.
The authors suspect that dogs inherited the ability of their ancestor, the gray wolf, who can use it to sniff out hot bodies while hunting. ” The study is consistent with other research that describes the dog’s combined nose and brain as a sophisticated platform for processing a wide range of signals “Says Gary Settles, professor at Pennsylvania State University. He doubts, however, that the canine rhinarium can distinguish models of hot and cold objects from a distance, suggesting that the thermal sensing skills of dogs may not be useful for long-distance hunting.
Sources: Scientific Reports
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