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How Far Underground Can a Dog Smell? Vet-Verified Facts & FAQ

Written by: Nicole Cosgrove

Last Updated on May 6, 2024 by Dogster Team

A dog sniffing a scent

How Far Underground Can a Dog Smell? Vet-Verified Facts & FAQ

VET APPROVED

Dr. Paola Cuevas Photo

REVIEWED & FACT-CHECKED BY

Dr. Paola Cuevas

Veterinarian, MVZ

The information is current and up-to-date in accordance with the latest veterinarian research.

Learn more »

A dog’s nose is more impressive than we may realize. They use their noses to navigate and determine so much about their surroundings. Humans have relied on the incredible scent-detecting abilities of a dog’s nose for centuries for tracking, patrolling, and identifying. Furthermore, dogs have an incredible smell memory, and they use this to recognize people. A dog’s ability to pick up the scent is a true superpower.

Surely with that kind of superpower, nothing buried can go unnoticed. So how deep underground can their powerful noses pick up smell? Dogs can pick up a scent from 40 feet below the ground, but some factors influence how far they can smell.

Let’s have a look at the incredible power of a dog’s nose.

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How Good Is a Dog’s Sense of Smell?

Dogs’ noses are so impressive that they can smell separately through each nostril and will use the odor detected from each nostril to determine exactly where the smell is located.

A dog’s nose has the unique ability to separate air from the smell, while a human’s nose smells and breathes at the same time. This makes distinguishing scents for dogs much easier.

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A dog’s sense of smell is far superior to ours. Dogs’ olfactory bulb is approximately 0.31% of their brain volume1, whereas humans’ olfactory bulb is only 0.01% of their brain volume. Their sense of smell is about 100,000 times better than humans.

A dog’s olfactory epithelium contains about 225 to 300 million olfactory receptor cells. These highly specific cells are responsible for detecting odors. Each one of these cells has hundreds of cilia. In comparison, us humans have about 5 million receptor cells in our noses, with only about 25 cilia in each cell.

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Besides an amazing sense of smell, dogs also have a special organ known as the vomeronasal organ, which provides them with what some refer to as a second sense of smell. This organ is designed for chemical communication. The nerves from the vomeronasal organ connect directly to the brain and do not respond to usual smells.

In fact, these nerve cells respond to pheromones, many of which are odorless. The function of pheromones is to change and influence an animal’s behavior; for example, for breeding purposes or to help puppies feel calm and at ease with their mother.

How Far Can Dogs Smell?

We now know how incredible a dog’s sense of smell is, but how far can they smell?

Dogs can detect minute changes in odor molecule densities over brief periods. By sniffing the ground, tracking dogs can quickly identify which direction a person or animal has gone. Dogs can even detect human fingerprints that are a week old!

Dogs can detect a scent trail that is 5 to 14 days old2, and some bloodhounds can follow a scent trail for up to 130 miles. Environmental factors influence the distance at which a dog can pick up a scent, and some dogs, such as Bloodhounds, are more advanced in tracking scent as they are trained to do so.

The wind speed and direction, temperature, and weather influence how far a dog can smell. When the temperature is hot and dry, dogs can find it difficult to track scents, but when the ground is cooler than the air, or there is moisture in the environment, they can track scents easier. Light rain can enhance a dog’s scent, while heavy rain can make scent tracking more difficult. Naturally, the wind will carry scents, so wind direction will also affect how easily a dog can pick up the scent.

A trained dog can detect a scent from 20 kilometers or 12 miles away, depending on the weather. However, a hundred yards may even be too far if the weather is unfavorable. On a windy day, a dog can probably smell a person upwind from 20 kilometers away.

How Far Can a Dog Smell Something That Is Buried?

A dog’s nose can detect scents as far as 40 feet underground and as much as 80 feet underwater. There are reports of dogs detecting humans under 70 feet of mudslide in Oso. A well-trained dog can detect odors even through several inches of concrete.

A cadaver dog or Human Remains Detection (HRD) dog can detect the scent of remains deep underground depending on the type of soil, its aeration, and the presence of tree roots in the ground. HRD dogs can detect the scent not only in bodies but also in bone, blood spatter,  and cremated remains. They can even detect the smell of a body after it has been removed from a casket.

Dogs can detect a scent within a few minutes of death or several years later. There are reports of HRD dogs discovering 30-year-old remains buried in a 300 by 150-foot area3.

 Can I Deter a Dog’s Sense of Smell?

If you have reason to bury something in the ground, perhaps bones from a meal the night before, a dead hamster or farm animal, or anything that will emit an odor, your dog will smell it and will likely dig it up. They can also smell pests such as moles and rodents, which will encourage them to dig up your garden.

Unfortunately for your dog, their keen sense of smell is both a blessing and a curse. There are smells that dogs hate, which may help deter your dog, but this is no surefire way to keep them from digging up old chicken bones.

While most of us enjoy the smell of fresh herbs like rosemary and mint, your dog may find them offensive. Planting herbs in the area you don’t want them to dig may deter your dog.

Apple cider vinegar and white vinegar are both non-toxic and widely used in many households. Because most dogs dislike the strong acidic odor, spraying some around the area may help deter them.

Citrus scents are at the top of the list of smells that your dog dislikes. Lemons, limes, oranges, and grapefruits smell unpleasant to dogs because the potency of the citrus may irritate their nose.

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Summing Up

It’s clear that if dogs were superheroes, it would be because of the incredible ability of their noses to pick up scents. It seems there is no material that dogs can’t smell through; they can smell through water, soil, and even cement! Their noses can smell things buried at least 40 feet deep and pick up scents that are weeks old. While there are smells that dogs dislike, one smell is unlikely to mask another one, as they can perceive them differently.


Featured Image Credit: Pawtraits, Shutterstock

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