Why Does My Dog Constantly Smell My Other Dog?

Have you ever noticed your dog getting up close and personal with another dog’s rear end upon meeting them? This behavior may seem odd or impolite to us humans, but it’s perfectly natural for dogs. Sniffing and investigating each other’s scents provides dogs with a wealth of information and is an important part of their communication and socialization.

When dogs come nose-to-nose, they’re not just saying hello – they’re gathering intel. A dog’s powerful sense of smell allows them to pick up clues about another dog’s identity, sex, reproductive status, diet, territory, mood, and more. While the behavior may seem intrusive or unsettling to us, it’s simply how dogs get acquainted in their canine world. Understanding why dogs smell each other can provide insight into the unique ways our furry companions interact.

Scent as Communication

Dogs have a highly developed sense of smell that gives them a wealth of information about their surroundings. A dog’s sense of smell is many times greater than that of humans. The olfactory center in a dog’s brain, which is devoted to analyzing smells, is about 40 times larger than in humans (1). Dogs have up to 300 million olfactory receptors in their noses, compared to only about 6 million in us. Their powerful sniffers have played an indispensable role in human endeavors such as law enforcement, search and rescue, and more.

For dogs, smells give information about identity, emotional states, and health. A dog can identify its owner or other familiar people by their scent alone. A dog can also detect subtle changes in their humans’ scent and mood (1). Smells allow dogs to gather a great deal of information critical for communication and social interaction with other dogs and animals. Their incredible sense of smell allows dogs to pick up on invisible “messages” and signals from other dogs and animals using pheromones and other chemical cues.

(1) https://vcahospitals.com/know-your-pet/how-dogs-use-smell-to-perceive-the-world

Natural Dog Behavior

Sniffing and smelling are innate behaviors for dogs. A dog’s sense of smell is much stronger than that of humans, with as many as 300 million scent receptors in their noses compared to only 6 million in people. This allows dogs to gather far more information about their surroundings and other animals through their sense of smell.

According to research, the olfactory system likely plays a key role in social functioning for dogs. Smelling other dogs provides them with chemical information related to identity, sex, and health/reproductive status. Dogs also leave scent marks for other dogs to detect. So sniffing is a major component of canine communication and social interaction.

When a dog persistently smells another dog in their home, it’s their natural way of gathering information. They are likely looking to identify the other dog and gain insight into their health, stress levels, diet and more through chemical signals in their body odor and secretions. It helps establish social connection and relationships within a pack. So frequent sniffing between household dogs is normal canine behavior.


[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8388720/

[2] https://www.thesprucepets.com/why-dogs-like-to-sniff-4687196

Social Hierarchy

When dogs meet each other, they initially use their sense of smell to determine one another’s social status and roles. Dogs have complex social structures, and smelling allows them to establish a hierarchy between dominant and submissive roles (source). Dominant dogs will sniff the rear and genital areas of submissive dogs to reinforce their higher ranking. Submissive dogs may role on their backs and expose their bellies to show the dominant dog that they accept their lower status. This sniffing behavior allows dogs to avoid conflicts and establish peaceful relationships.

Dogs can also smell hormonal changes related to stress and anxiety that indicate whether a dog views itself as dominant or submissive. The smells provide social cues for appropriate behavior during interactions. While sniffing may seem invasive to humans, for dogs it is simply a normal communication mechanism to determine where each dog fits in the social order.


Dogs have a powerful sense of smell that gives them a wealth of information about potential mates.

When dogs sniff the anal and genital areas of other dogs, they are detecting pheromones and other scents that provide details about reproductive status and health. Intact male dogs can detect when females are in heat through changes in their odor and will frequently attempt to mate with females who are in estrus.

According to research, a dog’s vomeronasal organ contains sensory receptors that detect pheromones and transmit information about reproductive status to the limbic system of their brain, which regulates mating behaviors (Source).

By constantly sniffing each other in these areas, male and female dogs are communicating about readiness and willingness to mate. These sniffing behaviors support mating between dogs by providing critical information about fertility status.

Health Checking

Dogs have an incredible sense of smell that allows them to detect illness and injuries in humans and other dogs. According to a study published in Nature, dogs can be trained to detect diseases like cancer or malaria through odor signatures in things like breath and skin cells1. This ability likely stems from their ancestral origins where dogs needed to be able to detect sick or injured pack members. By constantly sniffing each other, dogs are essentially performing health checks to ensure the pack remains healthy and strong.

When dogs smell cancer or other diseases, they are detecting the volatile organic compounds that are produced during cancerous metabolic processes. Their powerful noses can pick up on subtle changes in these odor signatures that may not be apparent to humans. Dogs can even be trained to detect COVID-19 through smelling skin swabs or breath samples2.

So when dogs are obsessively smelling another dog, they may be picking up on underlying health issues or changes in smell that humans can’t detect. It’s a natural pack behavior to ensure the health and safety of the group.


A dog’s sense of smell plays an important role in strengthening social bonds between canines.[1] When dogs sniff each other, they are gathering information about the other dog’s identity, sex, and health status. This allows dogs to recognize members of their social group or “pack.”

According to research, the act of sniffing triggers the release of oxytocin, also known as the “love hormone,” which helps facilitate bonding.[2] Oxytocin levels have been shown to increase after friendly dog-dog interactions, similar to the oxytocin surge that occurs between mothers and offspring. This suggests scenting behaviors help reinforce social attachments between dogs.

Within a household, dogs will frequently sniff each other and their owners. The familiar scents provide comfort and reinforce family membership. Dogs will often lick each other’s faces when greeting, providing additional olfactory information. These behaviors help strengthen bonds between cohabitating dogs.


Dogs are naturally curious creatures who experience the world primarily through their noses [1]. Smelling their environment and other animals allows dogs to gain information about their surroundings. When dogs encounter new smells, it can be interesting and exciting for them, providing mental stimulation and enrichment. A dog constantly sniffing another dog is likely just very curious about the other dog. They are investigating the new smells in order to gather details and learn more.


Allowing dogs to sniff and interact using their sense of smell is important for their well-being. Here are some recommendations for allowing natural sniffing behaviors:

Let dogs sniff each other politely during greetings. Sniffing helps them become acquainted and exchange information. Punishing or inhibiting this natural behavior can cause stress. As long as the greeting remains calm, allow the dogs a chance to sniff each other.

Do not punish or discourage smelling behaviors without cause. Sniffing the ground, other dogs, and people is normal canine behavior. Only redirect your dog’s attention if the sniffing becomes obsessive or inappropriate. Otherwise, let your dog explore the world through their nose.

Build in dedicated “sniff time” on walks. Rather than insisting on a brisk pace, let your dog meander and sniff. This provides mental stimulation and leaves them happier than just walking quickly from point A to B. Allow several minutes of sniffing per walk.

Try “nosework” games and training. These build confidence and strengthen the bond between you and your dog. Food puzzles, “find the treat” games, and scent training are great nosework activities.

Sniffing and scent communication is fulfilling and enriching for dogs. Understanding this natural behavior allows dogs and owners to enjoy its benefits.


In conclusion, constant sniffing between dogs is a natural behavior that serves several important purposes. Smelling each other helps dogs gather information, establish social connections, detect health issues, and reinforce bonds. A dog’s sense of smell is their primary way of experiencing the world and other dogs. While the habit may seem peculiar to humans, for dogs, sniffing is an essential form of canine communication and social interaction. Recapping the main reasons dogs smell each other:

– Sniffing allows dogs to pick up chemical signals that communicate identity, sex, health status, emotions, and more. It is a key way dogs get to know each other.
– Dogs use smell to establish social hierarchies within a group. Constant sniffing reinforces these relationships.
– Sniffing can indicate interest in mating, especially when a female dog is in heat.
– Dogs sniff to detect potential illnesses or issues. Their sense of smell is highly attuned to changes in scent that may reflect health problems.
– Frequent sniffing helps strengthen social bonds and relationships between dogs. It is a way for dogs to reconnect.

In summary, smelling is deeply ingrained natural dog behavior. While it may seem impolite to us, for dogs, sniffing is an essential part of their social interaction and understanding of the world around them.

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