What is Scent Detection?

From the first domesticated dog, humans and dogs have evolved together. Originally, dogs helped humans in tracking and hunting game. Group hunting conferred a selective advantage: finding food increased the chances of survival.

Scent detection canines identify a target scent against a complex, shifting background of odors (1).  Canine olfaction surpasses human: dogs can detect parts per trillion. Even with our limited sense of olfaction, humans can detect scents at a distance, such as smoke of a fire burning in a room down the hall, breakfast from another floor, or cinnamon buns in a mall food court. Dogs smell much farther away. The main advantage with trained sniffer dogs is that they generally search larger areas faster, safer and cheaper than inspections by humans or chemical detecting robots.

Since the last century, public knowledge of the science of canine olfaction has increased dramatically, encompassing a wide variety of disciplines (2). Dogs can be trained to detect target odors including:

  • Medical – detecting cancer, infections, diabetic alert dogs (a subset of service dogs)
  • Tracking – tracking escaped convicts, patients with dementia who go missing, other pets that go missing, and dangerous predators that are a risk to public safety
  • Search and rescue  – Finding live humans after disasters, searching for recent human remains, and historic human remains, detecting graves hundreds of years old through changes in the surrounding environment
  • Pests – Detecting bed bugs, rodents
  • Hunting – birds, foxes
  • Wildlife Preservation – finding endangered species, counting populations of animals
  • Legal – detecting illegal substances such as narcotics, explosives, currency, electronics smuggling
  • Pets – pet dogs compete in
    • Nosework aka sporting detection, finding essential oils (see below)
    • Tracking*
    • Mantrailing*
    • Obedience
    • Scent hurdle racing, dog finds handler scented dumbbell
    • Barn hunts
    • Antler hunts
    • Field tests, and many more.

*Curran et al. (2005) explain: “There is a difference between canines that are used to track human scent, trail human scent, and identify scent. Tracking canines are trained to use human scent and environmental disturbances to locate the track of a person but are not given an initial scent to follow. Trailing canines are scented on an object and then asked to determine if the scent of the person can be detected in an area (uncontrolled environmental conditions) and followed to the source or until the trail ends. Human-scent-identification canines are presented with a person’s scent collected from a crime scene and then asked to match the odor from a selection of scents under semicontrolled environmental conditions”(3).

The ways we relate to dogs continues to evolve over time, and we still have much to learn about canine olfactory science. For a short lesson on how canine olfaction works, watch Ted-Ed’s “How do dogs “see” with their noses?” at https://www.facebook.com/TEDEducation/videos/2734615186551670/

This video shows an experienced bed bug detection dog searching a lineup of objects as part of maintenance training. He communicates the position of the bed bugs with an indication (aka trained formal response): by freezing like a statue, staring with his nose as close to the bugs as possible.

We start training scent detection to puppies as young as 5 weeks of age. This video shows the first training session with Lula, a Brittany puppy. Note that the searches are easy, short and rewarding to build drive for searching for target odor. Do not frustrate your green dog by presenting many equally attractive options! The first box they see should be the hot box. Setting the dog up for success reduces confusion, frustration and errors by making the right choice obvious. It should be easy to succeed and difficult to fail. Note that puppies and dogs need hundreds of repetitions before making it harder.


Nosework (aka scent work, sporting detection, nosework, scent detection) is a new and growing dog sport that uses training techniques similar to those employed to teach law enforcement dogs to detect narcotics and explosives, to search for legal substances. Dogs who enjoy sniffing are easily trained using positive, rewards based training to love searching for scent. Scent dog training is a great way to share mental and physical exercise with your dog. Once you’ve learned how to do nosework, you can enjoy doing it every day, with minimal supplies. All ages, sizes, breeds, reactive dogs and dogs with mobility challenges are welcome.

Nosework is all about having fun with your dog. Scent detection is a great way to enjoy mental and physical exercise together. We use scent dog training techniques similar to those employed to teach law enforcement dogs to detect narcotics and explosives, to teach pet dogs to search for legal substances. We follow scent detection protocols designed to train reliable, sniffer dogs, using high value rewards. Any dog that likes to sniff and is interested in food or toy rewards can learn nosework.

There are many flavors of nosework competition. Nosework competitions test teams abilities to searches in varied environments, including containers, interior, exterior and vehicle searches. At the highest levels, dogs must ignore food and toy distractions, and search thousands of feet, to find all the hidden odors, given limited time.

Sporting Detection organizations that hold competitions include:

Whatever your eventual goals, scent dog training is a fun and fascinating challenge that builds a stronger bond with your dog. We’ll show you how to train your scent dog so that he loves to search, find, and show you the location of the target odor.

If you’re in the Calgary area, join us for weekly nosework classes at Kayenna Kennels. Or learn nosework online.


  1. Nathaniel J. Hall,Clive D. L. Wynne. Odor mixture training enhances dogs’ olfactory detection of Home-Made Explosive Precursors.Heliyon 4 (2018) e00947. Retrieved at: https://reader.elsevier.com/reader/sd/pii/S2405844018314890?token=7BF0930EE542C417939ACE255C8C10FC6296170968DBC63BF232C6C305DB6A640E3AB4EAF06E3717D2C41F80B7FDF97D
  2.  Canine Olfaction Science & Law (Advances in Forensic Science, Medicine, Conservation, and Environmental Remediation) Ed. Tadeusz Jezierski. 2016.
  3. Curran, Allison & Rabin, Scott & Furton, Kenneth. (2005). Analysis of the Uniqueness and Persistence of Human Scent. Forensic Sci Commun. 7.


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