Occasionally I would let my dog sniff ad nauseam. But most of the time, I would tug him and force him to march along with me. It was my “exercise” after all. Plus, he’s benefiting from the walk, not the sniffing.

Wrong. Science shows their mental wellbeing depends strongly on sniff time. I should have separated my exercise time with his much needed “sniff walk.” For dogs, this is basically their version of reading a newspaper, social media feed, and group chat all at once. Let them have their “sniff fest” while you wait around like a good shepherd. If you must combine your exercise with their walk, some trainers recommend keeping the walk moving for 70% of the time and letting the dog take the lead to sniff for the other 30%. Buy a 10 to 15 foot leash to give them more flexibility and space. And dedicate one walk a day or week as a dedicated “sniffari” where you don’t worry about distance or pace. Let the dog decide the route and the stops.

Dogs have a massively enlarged olfactory system compared to humans. They have roughly 10,000 to 100,000 times more sensitivity to odors depending on the compound. A huge portion of their brain is devoted to smell processing, especially the olfactory bulb, which is proportionally about 40 times larger than ours relative to brain size. When a dog sniffs, they’re not just detecting “a smell”: they’re parsing layers of information: who was here, how long ago, stress hormones, sex, diet, health status, and even emotional state.^[1]

They also use a special structure humans barely use called the “vomeronasal organ, “which helps detect pheromones which are chemical social signals. So when a dog stops at a fire hydrant for 30 seconds, it’s basically “reading” a complex chemical story left by other dogs.^[2]

On top of that, sniffing actually changes their brain state. Studies show sniffing activates reward pathways and increases engagement and focus. It’s not just passive sensing: it’s mentally enriching and calming at the same time. This is why preventing dogs from sniffing can actually make walks more stressful or unsatisfying for them.^[3]

The closet parallel to human behavior is  

• Reading text messages, social media, and emails (information about people you know)
• Hearing gossip or updates about friends (“who did what, when”)
• Quickly scanning a busy environment like a party or airport and picking up social cues
• Browsing photos or posts that give context about people’s lives over time

So if a dog sniffing a tree is “reading a detailed social timeline of every dog that passed by,” then a human equivalent might be scrolling through messages, updates, and background context about your social world all in one feed.

There’s also an emotional component. Just like humans feel curiosity or satisfaction from social information, dogs get dopamine release from exploring scent trails. 

So a slow sniff-walk is not “wasting time” to a dog: it’s mentally fulfilling, like letting a person catch up on everything they’ve missed socially in one sitting.

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^[1] Päivi Berg, Tapio Mappes, and Miiamaaria V. Kujala, “Olfaction in the Canine Cognitive and Emotional Processes: From Behavioral and Neural Viewpoints to Measurement Possibilities,” Neuroscience & Biobehavioral Reviews 157 (2024): 105527, https://doi.org/10.1016/j.neubiorev.2023.105527.

^[2] Erica F. Andrews et al., “Extensive Connections of the Canine Olfactory Pathway Revealed by Tractography and Dissection,” Journal of Neuroscience 42, no. 33 (2022): 6392–6407, https://doi.org/10.1523/JNEUROSCI.2355-21.2022.

^[3] Laetitia Maidodou et al., “Unraveling the Potential of Breath and Sweat VOC Capture Devices for Human Disease Detection: A Systematic-Like Review of Canine Olfaction,” Frontiers in Chemistry 11 (2023): 1282450, https://doi.org/10.3389/fchem.2023.1282450.