February 10, 2025, 4:20 pm | Read time: 5 minutes
It is nothing new that dogs have a much better nose than humans. A dog’s nose has around 300 million olfactory cells, making it 40 times more powerful than that of a human. This is why their special talent has been used for centuries in a wide variety of areas. But how far can a “normal” dog smell its owner?
Dogs are true masters of olfactory perception. The dog’s nose is a very fine organ, and so the four-legged friends can perceive things that are almost inexplicable to us humans. The term “sniffer dog” is, therefore, no coincidence. This impressive characteristic has been used for decades when hunting games, searching for people in disaster areas, or searching for drugs, weapons, and explosives at airports. Even diseases such as COVID-19, malaria, or certain types of cancer can be smelled by trained sniffer noses,1 But how far can “normal” dogs smell their owner?
Why Dogs Can Smell Better Than Humans
Perhaps we should first examine – in a very simplified manner – the major differences between a dog’s nose and a human’s nose. As in humans, various odor particles enter the nasal cavity through the nostrils in dogs. Glands in the nasal cavity moisten the ingested air so that the odor molecules come into contact with the olfactory mucosa. This mucosa covers the nasal turbinates, providing a surface area of about 200 square centimeters.
The up to 300 million olfactory cells in a dog’s olfactory mucosa transmit the odor particles to the brain. A special area of the brain is exclusively responsible for processing odor signals. This is where all incoming odors are processed and evaluated.2 With their nose, dogs can perceive odors at a concentration of one in a trillion – making their sense of smell around 10,000 times more accurate than that of humans. A dog’s nose can even detect complex variations in scents.
The Thing About Pizza and Its Individual Ingredients
While the human nose can detect the smell of a pizza, for example, a dog’s nose is much finer. It could theoretically distinguish not only every single topping on the pizza but also every single spice and the components of the sauce and dough. Dogs can also detect temperature differences in objects from a distance of about five feet. We humans would have to touch the objects in question to do this.
In short, the sense of smell is the main sense of dogs, says veterinarian Dr. Meaghan Thomas from East Ridge Animal Hospital in Chattanooga, USA. “This sense enables them to process real-time information from their immediate surroundings as well as past events.” For example, dogs can recognize by smell whether there is a predator or food nearby. This evolutionary trait has enabled dogs to survive and adapt.3
How Far Can Dogs Smell?
But back to the initial question: how far can dogs actually smell? “According to a study by the University of Leipzig, well-trained search dogs can follow scent trails over several kilometers, even if the trail is several days old,” explains dog trainer Katharina Marioth. Some reports from the field – for example, from rescue dogs or man trailers – show that dogs can follow tracks over more than ten kilometers. However, this depends on various factors such as weather, training conditions, or dog breeds.
“Some studies indicate that environmental factors such as rain, wind, and temperature have a strong influence on the durability of a track,” explains Maritoth in the PETBOOK interview. For example, the odor can spread further in favorable wind conditions, while rain and fog bind the odor molecules more quickly. “Wet weather improves odor binding on the ground. Strong winds can spread odors widely and make tracking more difficult,” says the expert.
These Dog Breeds Can Smell Particularly Well
“A study conducted by the University of Hanover in 2015 found a ratio of 60 to 40, even if the track was older than four weeks,” says Katharina Marioth. Another factor is the temperature. A dog cannot work at exactly 0 degrees. At -0.5 °C or +0.5 °C, however, this is not a problem. “This is because water ‘exists’ in three states of aggregation simultaneously at exactly 0 °C”.
But which dog breeds have the best sniffer noses? “Bloodhounds are known for their ability to follow tracks over longer distances and periods of time than other breeds,” summarizes the dog expert. “There are also many ‘nose specialists’ among the service and hunting dog breeds. Spaniels, Malinois, and German Pointers, to name just a few.
How the Sense of Smell of Certain Breeds Could Be Improved
Little research has been done into the factors that influence the different abilities of dogs to recognize smell. It is assumed that the genes for the olfactory receptors in some dogs can be altered and refined to a certain degree. “In combination with selective breeding aimed at improving the sense of smell in certain breeds, we can observe significant differences in the olfactory abilities of different dog breeds,” explains Dr. Meaghan Thomas.
The distance from which dogs can smell their owners cannot, therefore, be said across the board but depends on various factors. In addition to breed, weather, and environmental influences, the training level of the individual dog also plays a role. Through targeted scent training, owners can not only enhance their four-legged friends’ abilities in this area but also provide mental stimulation for their pets. But only on one condition, says Katharina Marioth. “It must be enjoyable for both parties, and then it’s all about practice, practice, practice.”
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How Owners Can Train Their Dog’s Nose
With nose work training such as mantrailing, it’s important to keep getting involved in new places and situations, says the dog expert. This gradually increases the dog’s confidence and sovereignty to trust its own “sense of smell.” “So slowly but surely increase the distraction, build in differentiation, increase duration and distance.” And very importantly: “We ALWAYS work with a reward at the end.”
But there is another important thing to bear in mind, warns the dog trainer. “Be careful with search games, e.g., with food in the household: never teach your dog to hide things in cabinets, for example. This can end in a lot of chaos”, explains Katharina Marioth with a laugh.