How Long Can a Dog Pick Up a Scent?

Smell is a dog’s most prominent sense. It’s estimated that a dog’s sense of smell is 40 times greater than a human being’s! With that in mind, you may now be wondering to yourself, ‘how long can a dog pick up a scent?’

How long can a dog pick up a scent? Some dogs can detect and follow a scent months after the original trail. Other dogs may not be able to pick up a scent trail after 24 hours. There are 3 factors that influence the power of scent in a dog. The first factor is the breed of dog (genetic make-up and the number of scent receptors). Second, the environmental conditions around the scent. The last factor is type or amount of training the dog receives.

In this article, we will discuss which breeds can pick up scents over the longest time. We will also explore how police dogs and k9’s pick up scents, and what factors affect a dog’s sense of smell.

So, if you’re ready to learn more about the fascinating factors that determine how long a dog can pick up a scent, then let’s get to it!

How Long Can a Bloodhound Pick Up a Scent?

Bloodhounds can follow a trail for more than 130 miles! That’s because they have 300 million scent receptors! That’s the highest number of scent receptors amongst all dog breeds.

With their large nose, open nostrils, and long ears, they are genetically predisposed to be the ultimate tracking dog. Why? Their long ears sweep up a scent from the ground. And then their loose skin around their head traps and retains the smell for up to 300 hours!

Amazing, isn’t it? This is why bloodhounds rank number one for dog breeds with the best sense of smell.

Their stamina and determination, in addition to their unique sense of smell, makes them an exceptional trailing dog.

How Long Can a Basset Hound Pick Up a Scent?

The Basset Hound is second only to the Bloodhound in its scenting ability.

This breed was born to follow a scent trail. Its body is low to the ground. In fact, the name Basset Hound comes from the French word ‘bas,’ meaning ‘low’. Their long and droopy ears sweep smells up off the ground into its powerful ‘sniffer.’ The loose skin around its chin (known as the ‘dewlap’) helps to trap and retain the scent for days.

This breed has over 220 million scent receptors, which is significantly higher than a human’s. They can even isolate a single smell out of hundreds and follow it precisely.

About the Basset Hound

How Long Can a Beagle Pick Up a Scent?

Don’t let the size of this little dog fool you.

The smallest of the hound breeds, Beagles have just as many scent receptors as a German Shepherd (between 220 and 225 million).

Its wet nose helps attract and hold scent molecules for days. It can follow a smell for miles, in the air, and on the ground.

The Beagle is also able to pick-up more than 50 distinct smells, differentiate between them, and then remember the scents for future use.

This breed is especially good at detecting bed bugs. The parasites emit a sweet, yet musty smell that the dog can pick up on almost immediately.

It’s no wonder the small but mighty Beagle ranks third amongst its peers for the best sense of smell.

How Long Can a German Shepherd Pick Up a Scent?

This breed of dog has up to 225 million scent receptors.

German Shepherds have an incredible ability to air-scent. It lifts its head high in the air (rather than keeping it low to the ground) while casting about to catch a scent. This means it can track a human scent carried by the wind for hours, even days. It can also pick up a scent that is up to 40 feet underground or in 80 feet of water!

The German Shepherd’s outstanding sniffer is why it ties for third with the Beagle when it comes to dogs with the best sense of smell.

An excellent tracker, the German Shepherd is highly versatile and very obedient. This makes it an ideal breed for a service dog for police, the military, and search/rescue teams.

How Long Does a Dog’s Scent Last?

Opinions are mixed on this.

Some experts believe that scents can last up to 14 days, whereby they can be picked up by a trailing dog.

Other experts believe most smells dissipate within 5 days.

At the extreme, there are experts that say odors remain detectable for years.

There is truth to all these perspectives. Why? A viable scent is different from breed to breed and dependent upon various environmental conditions.

How Far Away Can a Dog Pick Up a Scent?

It’s no secret that dogs have a fantastic sense of smell.

They track smells not only on land but in the air and under water as well. In fact, their olfactory system works so well that they can detect scents that are diluted 1 to 2 parts per trillion!

How do dogs “see” with their noses

How Do Police Dogs Pick Up a Scent?

The Belgian Malinois is currently the most common breed used in police work.

They track a scent by putting their nose close to the earth to detect human skin particles that have fallen to the ground or onto shrubbery.

These dogs are often cross-trained, which means they can track drugs as well as humans.

The Belgian Malinois can also detect substances such as explosives, currency, blood, and contraband electronics, such as illicit mobile devices.

How Far Can a K9 Smell?

The German Shepherd is the breed that often comes to mind when we hear the term ‘K9’ or ‘K-9‘ dog.

Their outstanding ability to track a scent, not only on the ground but in the air and under the water as well, makes them a top choice for a service dog. They will pursue a scent trail anywhere from 5 days to 2 weeks, depending on the circumstances.

how far can a dog pick up a scent
You can train the German Shepherd as a K9 for police work

A K9 police dog is so well-trained with a super-sensitive nose that can smell a single marijuana seed up to 15 feet away! It can also detect marijuana residue on human clothing that smoked 2 nights before!

K9’s can even smell fear, not the emotion itself, but the physical manifestation of fear. This includes an increase in sweat or body odor emitted when a person is feeling nervous, anxious, or afraid.

Can A Dog Smell Its Way Home?

Recent studies have shown that a dog relies on familiar smells to find its way home.

It is not uncommon for specific breeds to follow a scent trail (particularly that of its owner) to its home at a distance of 10 miles away. This feat is dependent on the right wind conditions and little precipitation in the air.

I have a personal story to share. I lost my Poodle Lucy in the park twice. Both times, she beat me home and was waiting at the front door. Amazing!

What Factors Affect How Long a Dog Can Pick Up a Scent?

The main factors that affect how long a dog can pick up a scent include the following.


Genetics influence the number of scent receptors (which vary from breed to breed). This directly affects a dog’s ability to track a smell. The more receptors, the better!

Dogs also have a “second nose” or their Jacobson’s organ. This is located inside the nasal cavity. It opens into the upper area of the mouth. Their second nose detects not only odors but also pheromones and other chemical substances.

Environmental factors

These weather conditions can often affect a dog’s ability to track a scent:

  • Air temperature;
  • Precipitation (rain and snow);
  • Humidity; and
  • Wind conditions.

Precipitation is the most significant factor. This is because smells in the air and on land get diluted with increasing air moisture, making them more difficult for dogs to track.


The type and amount of training a dog receives to scent track is another determining factor.

Various methods can be used, such as associating a favorite toy with the smell of drugs. This can be something as simple as a towel, which is used for a fun game of tug-of-war with the handler, containing a bag of marijuana rolled up inside of it! This method is just one example of ‘tricks’ used to sharpen a dog’s already amazing sense of smell.

Can Dogs Sense As Well As Smell?

As you’ve read in this article, dogs are gifted to smell many things.

Did you know that dogs can also sense a change in the weather like a storm coming? Sometimes it can be precise as 15-20 minutes away. If you want to know more, have a read of this article on our blog.


In conclusion, some dogs can detect and follow a smell months after the original trail was laid. Others, however, may not be able to pick up a scent trail after 24 hours.

How long a dog can pick up a scent is dependent upon the genetic make-up of the breed, the environmental factors involved as well as the type and amount of training it receives.
It’s no wonder that ‘while we hear or see something in a single moment, a dog smells an entire story from start to finish.’ – TED-Ed (


Michelle loves enjoying the outdoors with her dogs. She grew in a big house near the beach with German Shepherds. Nowadays, Michelle has down-sized her dogs to poodles, proving small dogs can enjoy the outdoors too! Her dogs enjoy playing fetch, swimming, and long walks. Michelle and her dogs enjoy escaping the city limits to hike, camp, and swim.

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