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Many dogs sniff the ground, and when they do so, they appear to be very concentrated. This is not surprising considering that dogs use a good percentage of brain power for the amazing task of interpreting smells. 

Watching dogs sniff the ground can be fascinating. Whether your dog sniffs the ground on walks, before peeing or pooping or when he sees another dog, discovering what's behind this behavior can be surely fascinating. 

Why Do Dogs Sniff the Ground on Walks?

Dogs sniff the ground on walks for the simple fact that the environment around them provides a great stimulus package containing oodles and oodles of information. 

With a powerful nose blessed with up to 300 million olfactory receptors, and a sophisticated brain devoted to analyzing smells, it's no wonder why dogs spend so much time on sniffing.

It can be sometimes difficult for us humans to comprehend why dogs are so interested in sniffing. As humans with a history as hunter-gatherers, our sense of sight was far more important than our sense of smell when it came to gathering edible fruits and plants in our evolutionary past.

When our ancestors went on to develop three-color vision along with a substantial enlargement of the visual cortex, there was a simultaneous shrinkage of the areas meant to process olfactory information, explains John Bradshaw in the book "Dog Sense, How the New Science of Dog Behavior Can Make You a Better ."

Dogs, on the other hand, evolved to have poor color vision, (albeit better night vision compared to us humans) but a superior sense of smell. And when we talk about superior, we're talking about significantly superior! 

For sake of comparison dogs have an epithelium (the surface which traps odor molecules) that is 30 times larger than a humans' and boasts hundreds of millions of more neurons responsible for binding to odor molecules and sending signals to the brain where they are interpreted.

With a sense of smell so advanced compared to ours, it may take a considerable amount of imagination to envision how the world may appear from a dog's perspective. While for us humans a walk often means window shopping or admiring gardens of roses, for dogs it means exploring a world of scents wafting through the air. 

 "A dog uses his nose, the way you use your eyes. To ask him to enter a new area and then tell him 'no sniff' is like putting a blindfold on you before you enter a new place. "~Sheila Booth,  Purely Positive Training: Companion to Competition

Dogs sniff the ground on walks for the simple fact that the environment around them provides a great stimulus package

Dogs sniff the ground on walks for the simple fact that the environment around them provides a great stimulus package

Why Do Dogs Sniff the Ground Before Peeing or Pooping?

Many dogs sniff the ground in quite a meticulous way before peeing or pooping, why is that? From a human perspective watching dogs spend so much time searching for the perfect spot to just expel a pile of stinky waste, may not make sense. And the issue becomes even irritating when you're at the other end of the leash, swearing in silence as you shiver from the cold!

However, at a closer insight, you might not be too far apart from Rover. If you are an avid reader and have magazines and newspapers handily stacked nearby the toilet, you may be sharing the same hobby with your dog. Welcome to the official Bathroom Reading Club!

Yes, because peeing and pooping in dogs has much more functionality than just eliminating earlier drinks and meals. Every time a dog pees or poops, he is leaving behind important information that will be "read" by other dogs or animals frequenting the area.

With such powerful noses, it's no surprise that dogs can deduce so much information about waste. Just as you use social networks to inform others about what's going on your life, in the doggy world eliminating is a way to communicate. 

Dogs therefore use pee and poop to leave behind interesting information (such as gender, reproductive status, what the dog ate for lunch and dinner etc.) for other dogs to "read.

 So if your dog tends to sniff a lot before peeing and pooping, chances are, he may be just "reading the headlines" and is looking for the perfect spot where his pee or poop can be noticed. 

Male dogs will lift their legs on vertical surfaces so that their pee is strategically deposited at a dog's nose-level. Other dogs may even go as far as to kicking dirt after pooping or peeing just for the sake of leaving visual and olfactory marks informing other dogs or animals that "Rover was here."

Introducing the "Olfactory Micturition Reflex"

But wait, there's more!  While it's true that dogs are attracted to leaving their information around for other dogs to gather, at a closer insight, the behavior is likely quite reflexive, so to say. So let's take a closer look at what may be going on "under the hood."

Introducing the dog's "olfactory micturition reflex." According to a study by Shafik (1994) dogs are equipped with a special reflex between the dog's nasal mucosa and its urethral sphincters.

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In the study, electrostimulation of the nasal mucosa induced a dog's urethral sphincter muscles to relax. Based on these results, Shafik therefore concluded that this reflex must play a role for inducing dogs to eliminate in the absence of a full bladder and in presence of specific odorants. 

It is possible, that this tendency to smell and urine mark may be stronger in intact male dogs. Among studies on rats, testosterone has been proven to act as a hormonal enhancer of olfactory acuity (Pietras and Moulton, 1974). 

Indeed, in neutered male dogs, the sniffing and marking behaviors tend to decline as testosterone levels decrease, although there is likely a learned component at play too. This explains why some dogs still urine mark despite being neutered. 

Many dogs sniff the ground before urine marking. 

Many dogs sniff the ground before urine marking. 

Why Do Dogs Sniff the Ground and Then Roll in it?

Another common scene in the dog world is a dog who is sniffing intently a spot and then decides to roll in it. What is going on with these dogs? 

In this case, dogs are likely intrigued by a particular smell that they happen to find so appealing, they want to retain some of it. It's sort of like going to a fancy boutique and sampling appealing perfumes.

 Too bad that the scents dogs find appealing to roll in don't coincide with what is appealing to us. Cow pies, rotten fish and stinky carcasses are some examples of disgusting things dogs love to roll in. 

There are several other theories about why dogs like to sniff areas and then roll in them. One theory has it, that, by rolling in poop, dogs are trying to camouflage their own smell so that they are less likely to be detected by predators, making for an easier catch. Another hypothesis is that dogs just want to advertise to other dogs what they have just found. 

Until dogs can talk, we can only make assumptions as to why dogs do the things they do. Regardless, one thing is for sure: dogs certainly look happy and proud of themselves when they roll in something disgusting, and the stinkier the better! 

Sniffing the ground when another dog is around can be a calming signal. 

Sniffing the ground when another dog is around can be a calming signal. 

Another Reason Dogs Sniff The Ground 

Finally, worth mentioning, is that sometimes dog sniff the ground as a way of sending a calming signal. Turid Rugaas author of the popular book: On Talking Terms With Dogs: Calming Signals, lists sniffing as a calming signal. You may therefore happen to see this behavior when a dog notices a person or other dog approaching at a slight distance.

 I have often seen this happening with my own dogs when I had dogs coming over for boarding and training. I actually encouraged this behavior because it seemed to have a calming effect on our guest dogs.

The first time I noticed this behavior was when I was given a shy dog for board and training. I found that my female Rottweiler repeatedly sniffed a spot a few feet away from her. 

There was really nothing to sniff there so I interpreted it as a deliberate calming signal. You can see her performing the sniffing in the picture above. 

Once more comfortable, both dogs were happily playing together. This behavior was often seen in future encounters with shy dogs. 

 On walks, it helped a lot to allow my dogs to walk on loose leashes as I have noticed they had a natural tendency to to sniff when they saw a dog approaching at a distance. 

This has helped avoid conflict as opposed to insisting in letting them heel with their heads high and away from the ground which I found was more likely to trigger conflict.

Now That You Know...

Now that you know why dogs sniff the ground, hopefully you have gained a closer insight of how your dog perceives the world. Following are some tips for dogs who sniff the ground. 

  • Provide your dog with some opportunities to sniff on walks rather than constantly asking your dog to heel. You can put the action of sniffing on cue by loosening completely the leash as you say: "Go sniff!" 
  • On top of allowing dogs to do something that comes naturally to them, sniffing on walks is also quite a tiring activity to dogs. The walk in addition to the sniffing will help tire the dog out and make for a more productive, entertaining walk.
  • If your dog shows an intent to sniff the ground when he is in a new place, you may want to allow your dog to sniff rather than insist in making him pay attention to you. Once he has satisfied his curiosity and feels more comfortable and safe, he'll then be much more ready to perform, points out dog trainer Sheila Booth. 
  •  If you see a dog coming your way, set yourself aside to provide distance  (and avoid frontal approaches) while allowing your dog to sniff the ground if your dog is naturally drawn to doing this. Chances are, if the other dog is reactive, this may help calm him down. 


  • Washington University School of Medicine. "New details in how sense of smell develops: Findings could help determine how dogs evolved such good noses." ScienceDaily. ScienceDaily, 10 August 2018. 
  • John Bradshaw, Dog Sense, How the New Science of Dog Behavior Can Make You a Better."
  • Purely Positive Training: Companion to Competition by Sheila Booth
  • Shafik A (1994). Olfactory micturition reflex: Experimental study in dogs. Biol Signals, 3:307–311.

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