Two dogs sniffing butts and saying hello in the park

Why Dogs Don’t Mind Sniffing Butts to Say Hello

We have all seen it — the common greeting ritual of dogs sniffing butts to say hello! While we may hold our noses and wonder how they can possibly stand the smell, our dogs seem to take great delight in this sensory way of connecting and checking each other out.

Yuk, we might think! Since dogs noses are so sensitive, how can they possibly stand the smell?

The primary reason dogs don’t mind the smell of sniffing butts is due to a thing called Jacobson’s organ. This is a secondary olfactory organ that many mammals, particularly dogs, have in their nasal cavities. It provides dogs with another way to smell. But rather than send an odor to their brains, this organ sends signals regarding chemicals and hormones.

Jacobson’s Organ

According to, “An average dog has a sense of smell that is about 100,000 times more sensitive than his owner’s partly because dog noses contain 150 million olfactory receptors while human noses only have 5 million. And dogs devote about 30% of their brain mass to the detection and identification of odors, while humans use a mere 5% for olfactory purposes.”

Jacobson’s organ (also known as the vomeronasal organ) has secondary receptors that provide critical mating information. It also assists dogs to identify members of their own pack including their mother. This is particularly important for young nursing pups who need to find their mother. You can read an article from the to learn more about Jacobson’s organ.

Why the Butt?

Dogs don’t mind sniffing other dogs’ butts, since they are not focused on odors but important information about another dog’s status and mood.

As it turns out, a dog’s anus has two anal glands that secrete a lot of chemical information. And this is the primary way that dogs communicate and learn about each other.

Dogs don’t mind sniffing other dogs’ butts, since they are not focused on odors but important information about another dog’s status and mood. Anal glands of dogs release pheromones, a type of hormone that indicates an emotional or sexual status. Here are some of the things that dogs learn when they sniff “hello”:

  • Whether the dog is friend or foe
  • Sex of the other dog
  • Sexual arousal and mating signals
  • Current mood
  • Signals indicating alarm or fear
  • Signs of aggression
  • Feelings of bonding from mothers or pack members
  • Identity of another dog via their unique chemical scent (like a fingerprint or name)
  • What the dog has eaten and if it leads to a food trail
  • Whether or not they have met this dog before

Aggressive dogs may initiate the butt sniffing, while a more submissive dog may wait his turn. If one dog is being overly “investigative” a fight may ensue. Sometimes a dog will simply sit down on his tail to signal “enough, already”!

Additional Ways Dogs Say Hello

Dog’s may also use their sniffing abilities to determine where a dog has been and who he has been with. They will do this by smelling another dog’s coat, feet, and nose. This is another reason that dogs scratch the ground (see my post) as a way to leave their scent and mark their territory.

Dog’s will also pay attention to another dog’s eyes– a direct stare could mean aggression. Rigid tails can be a warning and wagging tails can be an invitation. And of course, a dog’s bark or growl can communicate aggression, whereas a higher yip or upbeat bark could be a happy greeting.

These are the secondary signals a dog will pay attention to, especially if he cannot get close enough to sniff. That is why dog’s on leashes have a hard time. They usually meet head-on since they are walking beside their owner. This can cause discomfort and lead to aggression since neither dog has had a chance to check each other out. See my article “Why Is My Normally Nice Dog So Reactive When on a Leash?

When dogs have a chance to check each other out, the ritual can become very calming as they slowly gather information. Just like with humans, information is power. We fear what we do not understand. So, it is important to allow your dog to greet other dogs in a way that is natural to them.

Canine Nose Power Can Go Beyond Sniffing Butts

The success of search and rescue dogs relies primarily on Jacobson’s organ to sniff out a variety of chemicals to assist humans. With adequate training dogs can learn to sense cancer in humans, locate people in a natural disaster, help soldiers in war zones, and provide support for police officers.

Black lab walking with a soldier

Military personnel often have trained military dogs living with them in their encampments. These special dogs can sniff out bombs and help warn of encroaching danger.

Dogs have provided an invaluable and critical service during natural disasters such as hurricanes, tornadoes, fires, bombings, and collapsed buildings. Their sensitive noses can detect living as well as dead humans in the wreckage.

Specially trained police dogs often ride along with their police partners to assist with abating criminal activity. These dogs can sniff out drugs, pursue suspects, smell gun powder, detect bombs, chase down a criminal and keep him cornered.

In the medical field, dogs are being used to detect human diseases—cancer, diabetes, tuberculosis, and even malaria—from smell alone. Much of this is still experimental, but the work is very promising.

Dog’s Don’t Really Mind Sniffing Butts and Many Other Things!

Since this is the primary way dogs communicate and get information about each other, they don’t mind the sniffing. Additionally, this secondary olfactory system is not about the smell, but the investigation of various chemicals and hormones.

Therefore, it is not a repulsive activity for dogs. And, thankfully, dogs love to have jobs. Not only do they want to sniff out and learn about their canine world, but dogs also love to work with their human handlers and put their noses to good use for the benefit of their human pals.

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