As if dog noses weren’t already amazing as it were, scientists have recently discovered what they’re describing as an entirely “new sense” in dogs. In a double blind behavioral experiment, three dogs could detect stimuli of weak thermal radiation – check the scientific report abstract published February 28, 2020 here: https://www.nature.com/articles/s41598-020-60439-y.
So dogs can sense weak thermal radiation?
In the experiment, Swedish and Hungarian scientists trained three dogs to distinguish two objects based on the heat that the objects radiated. There was a neutral object with approximately ambient temperature, and a warm object which had roughly the same temperature as a furry mammal. Additionally, the scientists used magnetic resonance imaging to scan the brains of 13 dogs to compare their neural responses to similar heat stimuli.
All three dogs were able to successfully detect stimuli of weak thermal radiation in the experiments – in other words, they were able to identify the warm object from a distance.
The ability to sense this kind of radiation is known among insects like the black fire beetle and reptiles such as the Crotalinae and Boidae snake species. One other mammal, the common vampire bat, can also detect the same, using their ability to find skin areas that are rich in blood in order to maximize their yield when they bite after landing on a host animal. A smooth skinned area around dogs’ noses, known as the rhinarium, is uniquely moist, cold and packed with sensitive nerves, and scientists believed this was the most likely spot to receive temperature changes along with odors.
The area used for heat detection was determined to be the dog’s nose and the region of the dog’s nose that is able to detect this heat is only a few millimeters in size. Scientists determined that the location of the detected activation is clearly distinguishable from their hearing and smelling sense areas.
Facts about dog noses
Dogs have up to 300 million olfactory receptors (smelling receptors, or proteins that can bind odor molecules which has a central role in the sense of smell or olfaction) in their noses. Humans only have about 6 million.
A dog’s “smelling” system in their brain is about 40x larger than a humans.
A dog’s sense of smell is 10,000 to 100,000 better than a human’s. Analogies provided are that a dog can detect a teaspoon of sugar in a million gallons of water (two Olympic-sized pools worth), or they can smell one rotten apple in two million barrels of apples.
Dogs can easily wiggle each of their nostrils separately. They can smell separately with each nostril. Combined with their brain center, a dog can use these different odor profiles and put them together to determine exactly where the object they are smelling is located. This is similar to a human’s ability to see an object with each eye which aids in depth perception.
A dog can take in and breathe out air at the same time! Their cute wet noses are designed so that there is a continuous circulation of air, unlike humans who have to either breathe in or breathe out at any given moment.
Dogs have a special detection organ called the vomeronasal organ, which helps them sniff pheromones (chemicals that animals release with an important role in reproduction). You can read more about it here in this scientific abstract: https://www.researchgate.net/publication/325381241_The_dog_vomeronasal_organ_A_review
Image credit, dog’s nose Jade87