How Your Dog Creates Mental Pictures Through Scent

Analysis by Dr. Karen Shaw Becker

dogs smell dogs

Story at-a-glance -

  • If you’ve ever wondered if your dog can smell other dogs on you when you come home, the answer is a most definite yes
  • There’s no need to worry that your dog gets upset when she picks up the odor of another pet on your clothes or skin — she’s mostly just curious
  • When it comes to exploring their environment with their sniffers, research suggests dogs create mental pictures of the scents they pick up
  • Because dogs learn about the world by following their noses, it’s very important to allow your canine companion to spend some time sniffing outdoors each day
  • You might also consider K9 nose work, which is an activity you can do with your dog that can be both fun and beneficial

If you share your life with a canine companion or spend much time around dogs, you may have noticed that whenever you have an outside-the-house encounter with another dog, when you arrive home, your own dog goes beyond his usual ecstatic greeting to sniff you from head to toe.

“He knows,” you think to yourself. “He knows I left him home by himself and while I was out, I fooled around with another dog!” If you’re like many dog parents, you might even feel a flash of guilt!

The fact is, our dogs, with their keen sense of smell, really can pick up the odor of other dogs on us. But assuming they’re jealous or mad or sad when they do is pure projection on our part. Another word for it is anthropomorphizing — attributing human characteristics to a nonhuman species.

Simply put, your dog goes through life nose-first. His sense of smell is almost incomprehensibly acute when compared to yours. Dogs can pick up odors at around one part per trillion, which for humans would be the equivalent of smelling a teaspoon of sugar in 2 Olympic sized swimming pools!1

Dogs of Veterinarians Enjoy a Daily Smellapalooza

As you can probably imagine, veterinarians with dogs at home get a lot of sniffing attention at the end of a long day at the “office.”

“There’s no way to know exactly what’s going on in a dog’s mind, of course, but based on my pups’ reactions after I come home from work, I’d have to say that dogs are more curious than upset by these types of odors,” writes veterinarian Dr. Jennifer Coates in a post for PetMD.2

Coates points out that whenever we come in contact with an animal, we walk away with some of that pet’s odor-producing fur, skin cells, and/or saliva on us. When we arrive home, our pups can not only tell whether we’ve been around dogs or “non-dogs,” they can also pick up details about other dogs, including their sex, age, diet, and health status. (This is also what is happening when your furry BFF picks up his pee-mail on walks outdoors.)

“All of these details may not be evident to your canine companion after you have had a brief encounter with another dog,” writes Coates, “but rest assured, your dog has a general idea of what you’ve been up to.”

You can also rest assured your pup loves you just as fiercely as he did when you left home this morning. His nosey attention is just his doggy way of asking you how your day went.

Did You Know Your Dog Creates Mental Pictures as She Sniffs Her Way Through Life?

A 2018 study by German researchers provides evidence that dogs create mental pictures of what they’re searching for when they track a scent trail.3 In other words, they expect to find a certain thing when they’re sent sniffing.

The researchers tested a total of 48 dogs, 25 of which had either police K9 or search and rescue training. The remaining 23 were family dogs with no special training.

In the pre-test, two favorite toys (toys they liked to retrieve) were identified for each dog. Then in the actual test, the dogs were put through four trials in which they followed the scent trail of one of their two favorite toys. At the end of the trail, the dogs found either the toy they were expecting to find (the normal condition), or the other one (the surprise condition or a “violation-of-expectation paradigm” as described by the researchers).

Half the dogs were tested under the normal condition; the other half was were given the surprise condition, and their behavior was videotaped during each trial.

The researchers observed that in the first trial, the dogs who were given the surprise condition showed hesitation when they reached the unexpected toy, and continued to search with their noses, probably for the toy that had been used to lay the scent trail.

However, in subsequent trials, the dogs showed no hesitation, perhaps because they were rewarded no matter which toy they found, or because the test area still smelled like the toys from previous trials (even though it had been cleaned). According to study director Dr. Juliane Bräuer, the results of the first trial suggest that dogs hold a mental picture of their target when they track a scent, which means they have a solid expectation of what they will find.

Bräuer also found comparisons between the working and family dogs interesting. The K9s and search and rescue dogs retrieved the toys faster than the family dogs in the first trial, which was expected. But by the fourth trial, the two groups were retrieving the toys equally quickly.

Why It's so Important to Give Your Dog Lots of Sniff-Time

As we’ve established, dogs are brilliant sniffers by design, and I often wonder if pet parents truly understand their pet's need to explore the world with their nose. Some dog owners seem in such a hurry to get their walks over with, they don't give their pets a chance to satisfy their urge to sniff their environment.

Here's some excellent insight from animal behaviorist Marc Bekoff, Ph.D. on the potential for sensory deprivation and stress in dogs who aren't allowed adequate sniffing opportunities:

"Being smell-blind can be aversive to dogs. My recommendation is to let dogs sniff; let's not hijack one of their vital connections to the world. Let them sniff to their nose's content when they're tethered on a leash, or when they're walking and hanging out with friends and others and running freely.

As mentioned, not allowing dogs to exercise their nose and other senses could be a form of sensory deprivation that robs them of information they need to figure out what's happening in their world. Being smell-blind can indeed be stressful to dogs because they need odors and other information to assess what's happening around them.”4

Not every walk you take with your dog has to be a leisurely sniff-fest. But at least once a day, let your canine BFF sniff to her heart's content and feel good that you're letting your dog be a dog!

You Can Even Channel Your Dog’s Sniffing Aptitude into an Activity You Do Together

An excellent way to direct your dog's keen sense of smell and love of sniffing into an activity you can do together is K9 nose work, also called nose work and scent work.

Nose work is a sport for dogs and their owners that was created and sanctioned by the National Association of Canine Scent Work (NACSW). The activity is an offshoot of the training professional scent detection dogs ("sniffer dogs") receive. Elements of the training are used in K9 nose work, but for recreational purposes only.

Nose work encourages your dog to use her natural hunting drive and unique talent for picking up scents and locating the source. It isn't an obedience-based activity; instead, it works with your dog's natural instinct to hunt and track scents. There are few commands given during the activity, and no attention to the owner is required while the dog is working. Some of the benefits of K9 nose work include:5

Dogs easily burn lots of mental & physical energy doing searches

Searches can be done anywhere you can take your dog

No prior training is required, and no obedience is needed

In classes, dogs work one at a time and rest crated or safely in a vehicle between searches so reactive dogs can enjoy the activity, too

Shy or fearful dogs build confidence and overactive dogs put their energy into fun searches

Stronger bond between dog & handler as handler learns to observe, understand, and rely upon his dog

Best of all, any dog with a nose can participate in nose work, so you don't have to have a typical sniffer dog (e.g., a Retriever, German Shepherd, or Bloodhound) to get your pet involved in the sport.

Some dog parents have found nose work to be a great supplement to a behavior modification program. Focusing on scent detection can help reactive dogs learn to tolerate the presence of other dogs. It can help shy dogs grow more comfortable with their surroundings, and it encourages distracted dogs to stay on task.

Nose work is also beneficial for senior dogs, dogs recovering from surgery or an injury, dogs with hearing loss or eyesight problems, and retired service, working or competition dogs. It can also provide a great outlet for hyperactive dogs.

For more information, you can visit K9 Nose Work or the NACSW (National Association of Canine Scent Work). You can also search YouTube for K9 nose work videos and see lots of dogs and trainers/owners in action, plus a wide range of training techniques and uses for nose work.