How good is a dog’s sense of smell?

Not long ago, the media reported a “dog jump bridge” in Milton, Scotland. This is not the first time the bridge has been reported. Hundreds of dogs are said to have jumped off the bridge and committed suicide. Animal psychologist Dr. David Sands’s research suggests that these dogs are attracted by the smell of minks under bridges and jump down. Does a scent have such a deadly temptation for dogs?

There is no doubt that dogs are a kind of olfactory sensory animals. It has been concluded that if a dog’s sense of smell is defined as 100%, its sense of hearing is 70%, its sense of vision is 50%, its sense of taste is 20%, and its sense of touch is 10%. Unlike our ancestors, who gradually abandoned olfactory perception after gaining powerful vision, dogs pushed their sense of smell to the extreme of evolution. Compared with the only 5 million olfactory cells in our tiny nose, dogs have many more, at least tens of times as many as we do. For example, blood hounds have 125 million olfactory cells, fox hounds have 147 million olfactory cells, and German shepherds have 220 million olfactory cells. The area of nasal mucosa which distributes olfactory cells is not in the same grade as that of human and dog. Human only has about 5 square centimeters. Dogs not only have large nasal cavity, but also have many folds. For example, German shepherds have an area of 150 square centimeters. And the olfactory bulbs in the dog’s brain, which are used to analyze odors, account for a large proportion, accounting for one eighth of the brain weight, much more than the olfactory bulbs in our brain. What’s more, they have evolved a special “sniffing breath”, which is short-term, rapid breathing, up to 300 times a minute. This allows the nasal olfactory mucosa to filter out its interesting odor from a large amount of gas. Therefore, it has been inferred that dogs have at least 100 times the olfactory capacity of humans, and even Naubaus has raised the data to more than 1 million times. Of course, this data is exaggerated to make people feel a little unacceptable. Anyway, the world they perceive is totally different from what we perceive, beyond your imagination.

Strong sense of smell enables them to get more information through the smell. For example, when two dogs meet, they sniff each other’s buttocks, where they have anal glands, which, like business cards, can read each other’s information. They can even sniff out the health of their targets. As early as 1989, the famous medical magazine Lancet reported an example of a dog sniffing the canceration of its owner’s tissues. Later, many scientists wanted to use dogs to detect the occurrence of cancer, especially some Japanese scientists. The principle is not difficult, that the cancerous tissue may be able to release some abnormal substances, these trace substances scattered out can be captured by the dog’s nose or electronic instruments, so that people can be warned. The main problem now is to determine the chemical nature of those special substances, and then to train dogs or develop “electronic noses”, which, for the time being, may be more reliable.

How good is a dog’s sense of smell?

In addition, it should be pointed out that there are also great differences in olfaction among dogs. For example, Wang Liguang et al. tested with acetic anhydride in 2003, different dogs were able to react to acetic anhydride at 10-3 to 10-10 ppm (1 ppm = one millionth of gas content). The results of good and bad dogs were 107 times worse than those of bad dogs. Environmental temperature, humidity, time and other factors also affect the development of the dog’s nose. Er… Want to know people’s grades? 102ppm… Maybe even if Wang Xing’s performance is poor, he can throw out Blue Star’s n streets. Generally speaking, the longer a dog’s nasal cavity is, the more olfactory cells it contains and the more sensitive it is to smell. That’s why most of the dogs jumping off a Scottish bridge have long noses. In addition, dogs trained from an early age have a greater degree of olfactory development and can play a better role.

However, even if the odor is very stimulating to dogs, they usually do not lose their sense, that is to say, the odor of otters can not attract dogs to “suicide”. Dr. David Sands explained that it was also related to the bridge. The height of the bridge railings just blocked the dog’s view. The dog mistakenly thought that after jumping over the railings of the bridge, it would still be on the ground. Then he could happily go to the otter to play. As a result, only after jumping up can we know that the bottom, the face, is the pit!