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How Far Can a Dog Smell? Everything You Need To Know About The Canine Nose - PawSafe

How Far Can a Dog Smell? Everything You Need To Know About The Canine Nose

Photo of Tamsin De La Harpe

Written by Tamsin De La Harpe

how far can a dog smell

Canines experience the world wildly differently than we do, primarily through. So you may want to know how far a dog can smell? The Truth is, you wouldn’t be reaching if you said that noses “talk” in the canine world. Well, not sense,  but the smell is essential for canine communication and survival. 

Knowing how far away a dog can smell their owner, or how far away they can smell another dog in heat may even  be vital to keeping your dog safe in cases where they may run off or be lost. Don’t forget to spray your dog down in safe canine perfume if their smell is bothering you. 

Dogs dedicate tremendous mental effort to decoding olfactory signals from the environment. Canine olfaction is like our dependence on visual sense to navigate the world. To really answer the questions over how far a dog can smell, we are going to refer to Alexandra Horowitz’s book, Being A Dog. 

Canines are renowned for their keen senses, but their sense of smell is the most phenomenal. To put how powerful a dog’s smell is into perspective, they can detect a single drop of liquid in 20 Olympic-sized pools. That’s detecting chemicals at about one part per trillion. Few things are more impressive than that. 

But how far a dog can smell largely depends on several external factors, including:

Wind Speed and Direction 

A dog is “downwind” when the wind is blowing away from the person or object of interest towards them. Here, the wind direction is on the dog’s side, so they’ll catch the scent much faster. The opposite is true, whereby dogs detect scent molecules a bit slower if the wind is blowing away from them.

Wind speed influences how scent molecules spread out in the air. When there’s a gentle breeze, more odor molecules fan out in the air, so the dog’s moist, leathery nose captures them better. In contrast, smells move way too quickly when the wind is fast and strong, reducing a dog’s olfactory efficacy. 

Humidity and Rain

Increased humidity in the surroundings can positively influence a dog’s odor detection. Humid air holds more scent molecules than dry air, explaining increased odorant trapping and detection. 

While light rain provides this good humidity, heavy rain is damaging as it forces the scents to lower to the ground. Humidity due to foggy weather interrupts canine olfaction as it causes scents to linger excessively, increasing the time to decode smells.

Temperature

High temperatures cause a dog’s body to involuntarily switch from sniffing to panting to regulate temperature. Dogs also get dehydrated in high temperatures, leading to a dry nose that’s less effective at trapping scent molecules. Additionally, a dog’s ability to work significantly reduces on a hot day. 

Freezing temperatures also interfere with canine olfaction since scent molecules are trapped in the frozen air moisture. 

Health 

Certain health conditions like nasal tumors, injuries, and infections cause improper air flow, consequently impeding olfactory sense. These cause a runny nose and breathing difficulties, directly affecting a dog’s sense of smell. 

Why Do Dogs Smell Better Than Humans?

Dogs are nosy animals, and we have their 100 to 300 million scent receptors to thank for that. Humans only have about 6 million smell receptor sites, meaning dogs have 50 for every one of our olfactory receptors. This effectively places their smell 10,000 to 100,000 more powerful than humans.

As if that’s not enough smell power, the area of a dog’s brain dedicated to processing scents is 40 times larger than ours. They also have a vomeronasal region located right above the roof of their mouths to process organic scents like hormones for communication.  This is called their Jacobson’s organ.

Finally, inhaled air during sniffing separates into two distinct pathways, so their breathing and smelling occur completely separately. About 12 to 13% of each of your dog’s breath heads straight to their olfactory region, where they accumulate and avoid being exhaled.

What all these factors mean for your dog is that their smelling capability is on steroids. They just can’t get enough sniff: your dirty socks, your neighbor’s dog’s butt, crotches, everything. Be certain that your dog will poke their nose into your business to gather as much information about the world as possible.

Why Dogs Have Such a Strong Sense of Smell 

Dogs perceive the world around them with their nose, as we do with sight. The primary reason is that humans rely on sight and color perception to see predators and find colorful fruit. Dogs needed a scent to smell food from as far away as possible.  They create a three-dimensional image of surroundings across time because they can detect specific signals in real time and from the past.

So let’s look at how their sense of smell became so acute:

1. Hunting for Food

Dogs use their smell to track the odor of dynamic food sources. Even if most dogs don’t hunt their food, they still maintain this survival mechanism.

2. Communicating 

Dogs use the vomeronasal region of their brains to detect pheromones from another dog. They can tell another dog’s sex, reproductive and health status, what they’ve eaten, and even where they’ve been. A male dog is believed to smell a female in heat about three miles away. This is because of the pheromones released in the urine by the female in estrus. 

3. Detecting Danger 

Dogs can receive historical information about their environment through their nose. They can tell when there’s potential danger close and take precautions like rolling in stinky stuff to conceal their scent.

4. Homing Instinct

Dogs have an impressively strong homing instinct only contested by their feline counterparts. Homing instincts mean an ability to find the way back after traveling a long way far from home. An impressive example is Bobby the Wonder Dog, who covered 2,551 miles (4,105 km) to return home to Oregon from Indiana. 

5. Understanding the World

Dogs scan their surroundings with their nose like you’d check your environment to know where you are. Their noses help them judge their environment and can tell how friendly people are just by smelling them.

Dog Breeds with The Best Sense of Smell

Dog Breeds with The Best Sense of Smell

Dogs were bred for various purposes, so their sense of smell varies. Hunting dogs like Beagles and Bloodhounds have a much keener smell and more olfactory receptors than others. Don’t get us wrong, though, because dogs with an average canine smell will absolutely crush many species’ olfactory senses.

  • Bloodhound (300 million) –bloodhounds have the strongest smell in the species. They’ve been used as search and cadaver dogs since the middle ages. A bloodhound is called a scenthound, which refers to a group of dogs that rely primarily on their nose. In general, scent hounds likely have the strongest sense of smell. Other scent hounds include the Dachshund and Blue Tick Coonhound.
  • German Shepherds (225 million)— GSDs are valuable drug sniffers and military dogs. They may not be scenthounds, but as herding dogs, they are far more easily trained for elite detection work. 
  • Beagles (225 million)—These dogs are popular in narcotic control for customs and border control. These are perhaps the most popular of the scent hound breeds.
  • Belgian Malinois (225 million)—This is currently the most popular dog in the military for their extreme drive. 
  • Basset Hounds (220 million)—Coming close to Bloodhounds, Bassets are scent hounds for a reason.
  • Fox Terrier (147 million) – These dogs were initially bred to chase small game from their dens for their owners.
  • Dachshund (125 million) – The small but mighty Dachshund is a pro-sniffer able to detect scents below ground. This means they love to dig up gardens as they can smell any moles or critters in the earth you may not be able to see.
  • Labs and Golden Retrievers—We can see many of these two breeds working as service dogs able to detect seizures and breakdowns before they happen. Any breed with a hunting and retrieving background typically has a very developed sense of smell.

Brachycephalic (with a shortened muzzle) dogs have the worst senses of smell. These include French Bulldogs, Pugs, and Shih Tzus.

How Humans Have Revolutionized a Dog’s Smell

Humans also benefit massively from a dog’s impeccable olfaction. Dogs can detect scents far better than any man-made machine, with little room for error. 

Searching for Missing Persons

Search-and-rescue dogs are almost always on the front line of search parties looking for a missing person. They do this using air scenting, tracking, and trailing. Here is an amazing story of a Bloodhound using his amazing sense of smell to save a little girl:

Disease Detection 

Dogs can catch diseases early on by smelling them before any visible signs. They detect volcanic organic compounds (VOCs) in a person’s skin, sweat, urine, poop, or breath that indicate disease. A study found that trained dogs could detect lung cancer in people with striking accuracy.

 They can also detect insulin levels and seizures in diabetic and epileptic people as service dogs, potentially saving their lives.

Disaster Rescues

Dogs can sniff survivors beneath rubble after disasters like earthquakes and fires. Frida, the Mexican Labrador, rescued over 12 people and recovered 50 dead in the course of her rescue career.

Drug Sniffing 

Dogs can detect drugs almost effortlessly, making them valuable in airports and border patrols to spot smugglers.

Bombs and Fires

Dogs can detect the compounds in bombs, allowing law enforcers to act swiftly before damage occurs. Your pup can also sniff fires before you can, saving you and your family.

As you can see, man’s best friend is indispensable and 100% the best doggo. All we can tell our canine pals is thank you because they put their lives on the line countless times to save humanity.

Anti-Poaching Dogs

Perhaps one of the most beautiful ways we rely on a dog’s superior sense of smell is to use them to track down and apprehend poachers. Here is a video of the remarkable work these dogs dog:

What Can Cause Diminished Smell in Dogs?

Sometimes, dogs aren’t in their prime regarding their smell, and certain factors are responsible for this situation: 

  • Age: Just as human eyesight deteriorates with age, so does a canine’s smell
  • Dry nose: A dog’s wet nose traps scent molecules for processing, so dryness impedes their ability
  • Allergies and infections: Allergens and infections irritate the nasal lining, reducing olfactory capacity
  • Fatigue and heat: These cause excessive panting, reducing their ability to smell tremendously.

Final Thoughts

Dogs have a potent olfactory sense that enables them to navigate the world around them. Humans have harnessed a dog’s impeccable smelling capacity in rescues, disease detection, and drug sniffing. Age, medical issues, and infections can affect a dog’s ability to smell.

Meet Your Experts

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Tamsin De La Harpe

Author

Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.

Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.