Your Dog’s Nose Knows The Amazing Things : The Science behind The Dog’s Amazing Nose!
The canine nose does more than smell the roses. While humans primarily depend on their vision, dogs use both sight and smell to assess their surroundings and communicate. People spend more time interpreting visual data than olfactory information. Dogs are just the opposite.
Dogs devote lots of brain power to interpreting smells. They have more than 100 million sensory receptor sites in the nasal cavity compared to 6 million in people, and the area of the canine brain devoted to analyzing odors is about 40 times larger than the comparable part of the human brain. In fact, it has been estimated that dogs can smell anywhere from 1,000 to 10,000 times better than people.
Why do dogs “smell better” than humans?
Unlike humans, dogs have an additional olfactory tool that increases their ability to smell. Jacobsen’s organ (or the vomeronasal organ) is a special part of the dog’s olfactory apparatus located inside the nasal cavity and opens into the roof of the mouth behind the upper incisors. This amazing organ serves as a secondary olfactory system designed specifically for chemical communication. The nerves from Jacobsen’s organ lead directly to the brain and are different from the other nerves in the nose in that they do not respond to ordinary smells. In fact, these nerve cells respond to a range of substances that often have no odor at all. In other words, they work to detect “undetectable” odors.
Jacobsen’s organ communicates with the part of the brain that deals with mating. By identifying pheromones, it provides male and female dogs with the information they need to determine if a member of the opposite sex is available for breeding. It also enhances a newborn pup’s sense of smell so he can find his mother’s milk source, and allows a pup to distinguish his mother from other nursing dogs. With a quick sniff, a pup placed between two females will migrate to the mother that gave birth to him. Pups also have heat sensors in their noses that help them locate their mothers if they wander away.
The two separate parts of the dog’s odor detection system, the nose and Jacobsen’s organ, work together to provide delicate sensibilities that neither system could achieve alone. When the dog curls his lips and flares his nostrils, he opens up Jacobsen’s organ, increases the exposure of the nasal cavity to aromatic molecules and essentially becomes a remarkably efficient smelling machine.
Why do dogs have wet noses?
The canine nose works best when it is damp. The wet outer nose and mucus-covered nasal canal efficiently capture scent particles. Moisture is so important to the canine sense of smell, that dogs will lick their noses when they become dry. Smart canines do not want to miss out on important information due to a dry nose!
Within the last hundred years or so they’ve been trained to use that nose to help in a variety of other ways:
- Dogs can smell minute amounts of accelerants like gasoline, which is an aid to arson investigators. Researchers have not yet come up with a detection method as sensitive as a dog’s nose, which can sniff out around one-billionth of a teaspoon.
- They’ve been used by police and the military to detect drugs, bombs, and other explosives
- Dogs are often essential in search and rescue operations, able to track someone by scent.
- Dogs have been uniquely useful to archeologists with their ability to detect human remains.
- The medical world has recently discovered that dogs can be trained to detect certain types of cancer, including ovarian and prostate cancer, melanoma, and lung cancer as well as to sniff out malaria and Parkinson’s disease. According to research by Medical Detection Dogs, dogs can be trained to detect disease odor equivalent to a teaspoon of sugar diluted by the water in two Olympic-size swimming pools.
- Studies are being done to see if dogs can detect the coronavirus, as well.
The Olfactory Bulb is a bulb of neural tissue within the dog’s brain. It is located in the fore-brain and is responsible for processing scents detected by cells in the nasal cavity. It is approximately 40 times larger in dogs than in humans, relative to total brain size. A humans brain is dominated by a large visual cortex whilst a dog’s brain is dominated by the olfactory cortex. The Olfactory bulb accounts for one eighth of the dog’s brain.
The Olfactory bulb is extremely important to the dog due to its function of processing scent. Scent information travels from the Olfactory bulb to the limbic system which is the most primitive part of the brain (dealing with emotions, memory and behaviour). It also travels to the cortex (The cortex is the outer part of the brain that has to do with conscious thought). In addition to these two areas, information also travels to the taste sensory cortex to create the sense of flavour. Because olfactory information goes to both the primitive and complex part of the brain it effects the dog’s actions in more ways than we may think.
A dog’s sense of smell is probably more important to it than any other sense with the possible exception of touch (in a well-adjusted dog), the sense of smell and the sense of touch are the predominant senses for a dog and they are in place and fully functioning at birth, unlike hearing and sight, which develop later, and taste which although present at birth and connected to smell takes a back seat.
A dog has around 220 million scent receptors in his nose – that’s 44 times the number of receptors in our own human nose. The bloodhound exceeds this standard with nearly 300 million scent receptors!
The dog’s amazing scenting ability enables him to detect prey and helps him discern a females place in her sexual cycle. Each dog emits a personal olfactory profile that imparts a wealth of information to other dogs. The act of marking deposits information about the dog including age, sex, mood, health status, diet, size of pack and rank. A well socialised dog will engage in mutual sniffing with another dog as a polite greeting. A dog can smell adrenaline and pheromones that we cannot; they can therefore anticipate a fight or flight response from a person or animal before we have a clue. Although it should be noted – a dog cannot rationalise and distinguish why a person is kicking out great clouds of adrenaline in their presence. It may be that the human is scared stiff of dogs, but the dog won’t know this, only that this person is gearing up to fight or flee and should be carefully watched for any sign of an attack. So the Olfactory bulb is indispensable to a dog, it informs and it forewarns. It also allows the dog to assist us with specific jobs; the dog’s olfactory system is more sensitive than anything we can replicate with modern technology.
Dogs have been found to have high success rates at detecting cancer in humans through smell, they can sniff out drugs and explosives in busy airports for us – even if the object in question has been over-scented with something strong smelling they can separate the different scents, they can discern the direction of a target by sniffing and noting where the scent is marginally stronger in order to establish the ‘way the scent went’ for tracking purposes. They have mobile noses that can distinguish scent direction on the wind, moisture on the nose helps with this function.
They are truly brilliant where scent is concerned and the Olfactory bulb is the centre of this skill.
It is common knowledge that short snouted breeds of dog often show an impaired sense of smell and that all the dogs commonly used for scenting purposes are of the long snouted variety. Recently a study conducted by Michael Valenzuela of the University of New South Wales in Australia investigated the position of the brain within the skull to determine whether selectively breeding for differences in skull length between dog breeds has also reorganized the canine brain. The dogs with the shortest skulls—such as the pit bull and Akita showed significant brain reorganization. It was found that when selective breeding by humans shortened the snouts of certain dog breeds, it also morphed their brains to compensate. The whole brain was shown to have rotated thus relocating the olfactory lobe towards the bottom of the skull. This has sacrificed the sensitivity of some breeds sense of smell somewhat and it is for this reason that bulldogs are no good at tracking!
A simple scent can have a host of complex meanings, memories and emotional ties for our dogs as scent is directly linked to both memory and emotion via the limbic system, smell memories last for life and we can use scent to elicit as positive emotion to assist in cases of fear and phobia.
What do dog noses have that humans don’t?
They possess up to 300 million olfactory receptors in their noses, compared to about six million in us. And the part of a dog’s brain that is devoted to analyzing smells is about 40 times greater than ours. Dogs also have something called neophilia, which means they are attracted to new and interesting odors.
Dogs possess a sense of smell many times more sensitive than even the most advanced man-made instrument. Powerful enough to detect substances at concentrations of one part per trillion—a single drop of liquid in 20 Olympic-size swimming pools. With training, dogs can sniff out bombs and drugs, pursue suspects, and find dead bodies. And more and more, they’re being used experimentally to detect human disease—cancer, diabetes, tuberculosis, and now, malaria—from smell alone.
Dogs’ noses also function quite differently than our own. When we inhale, we smell and breathe through the same airways within our nose. When dogs inhale, a fold of tissue just inside their nostril helps to separate these two functions.
When we exhale through our nose, we send the spent air out the way it came in, forcing out any incoming odors. When dogs exhale, the spent air exits through the slits in the sides of their noses. The manner in which the exhaled air swirls out actually helps usher new odors into the dog’s nose. More importantly, it allows dogs to sniff more or less continuously.
Facts About Your Dog’s Nose and Amazing Sense of Smell
Here are eight more interesting facts about your dog’s sense of smell that prove that canines have superior noses.
- A dog’s nose has two functions—smelling and breathing.
According to Dr. Nappier, a canine’s nose has the ability to separate air. A portion goes directly to the olfactory sensing area (which distinguishes scents), while the other portion is dedicated to breathing.
- Dogs have the ability to breathe in and out at the same time.
“When sniffing, dogs’ noses are designed so that air can move in and out at the same time, creating a continuous circulation of air, unlike humans who have to either breathe in or out only,” says Dr. Nappier.
- Dogs have a special organ that gives them a “second” sense of smell.
According to Dr. Nappier, a dog’s vomeronasal organ helps them detect pheromones, which are chemicals that animals release that affect other members of the same species. This organ plays an important role in reproduction and other aspects of canine physiology and behavior.
- Dogs smell in 3-D.
Dogs can smell separately with each nostril. Just as our eyes compile two slightly different views of the world, and our brain combines them to form a 3-D picture, a dog’s brain uses the different odor profiles from each nostril to determine exactly where smelly objects are located.
- Dogs can smell the passage of time.
Dogs can detect the tiny reductions in the concentrations of odor molecules that occur over short periods of time. This allows tracking dogs to quickly determine which direction a person or animal has gone in by sniffing the ground.
- Dogs’ noses have evolved to help them survive.
According to Dr. David C. Dorman, DVM, PhD, DABVT, DABT, professor of toxicology at North Carolina State College of Veterinary Medicine, dogs have used their noses to assist with major life events since the beginning of time.
“Evolutionarily, a dog’s sense of smell helps them find a mate, offspring, and food, and avoid predators,” he says.
- Dogs can smell up to 100,000 times better than humans.
Dr. Nappier puts this tidbit into perspective with an awe-inspiring analogy. “A dog’s sense of smell is its most powerful sense,” he says. “It is so sensitive that [dogs can] detect the equivalent of a 1/2 a teaspoon of sugar in an Olympic-sized swimming pool.”
- Some breeds have a better sense of smell than others.
While all dogs have strong sniffers, Dr. Nappier says, “hound breed dogs have the best sense of smell.” Dr. Dorman points out that sturdy working dogs like German Shepherds and Labradors also rank high in their smelling abilities.
Can science build a dog’s “nose?”
Some of the most interesting work has been done at MIT, where physicist Andreas Mershin, in collaboration with his mentor, Shuguang Zhang, have tried to determine how a dog’s nose works and then create a robot that can replicate the process. The first difficulty is in figuring out exactly how smell works and then how the brain processes the information, since it’s been the least studied of our senses. Mershin set out to build an artificial nose, which would then lead us to understand how that nose works.
With a great deal of trial and error, Mershin and his team created the Nano-Nose, perhaps the first successful effort at artificial olfaction. It successfully passed rigorous testing by DARPA and, in the process, taught the scientific world a great deal about how dogs process scents. Still, the Nano-Nose is only a detector, the same way a carbon monoxide detector is. What Mershin is ultimately aiming for is the machine’s ability to interpret the data it receives and identifies. Wired did some excellent in-depth reporting on this, for those who want to dig into the science.
Currently, one start-up, Aromyx, is trying to harness artificial olfaction for commercial use. The company wants to put all 400 human olfactory receptors on to a chip, in contrast to the Nano-Nose, which uses only about 20 customized receptors, depending on its intended use. The ultimate goal, whether in the academic labs or the commercial world, is to build something that will react identically to scent as a dog’s nose does. And it may not be far off.
Your Dog’s Nose Is Definitely Their Superpower!
- Your dog’s sense of smell is their #1 method of gathering info
- Your dog’s canine olfactory system hub in the brain is 40x larger than yours (hear them gloating?)
- Your dog’s sense of smell is 1000–10,000x more sensitive than yours (more gloating)
- Dogs have 125,000,000–300,000,000 scent glands (varies by breed) compared to our measly 5,000,000 (gloating continues)
- Dogs can detect smells in parts per trillion, for example they could detect one rotten apple in two million barrels (which is about 752,000,000 apples)
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
APPLICATION OF DOG’S SMELL & PHEROMONES IN DETECTION & COMMUNICATIONS
