A dog may greet a person by bringing its nose close to clothing, shoes or parts of the body that carry a stronger scent. People can find the behavior awkward, particularly when a dog approaches a visitor at waist height. For the dog, sniffing is a routine way of collecting information about a new person or an unfamiliar environment. A greeting can be motivated by curiosity without carrying a special message about the person being sniffed.
The American Kennel Club explains that areas with more scent-producing glands attract a dog’s attention. A dog may also be drawn to an odor left on fabric. Where the dog can comfortably reach matters. A short dog and a large dog have different approaches to the same person, and the place where a nose lands can reflect simple differences in height as much as differences in scent.
Dogs also encounter scent in patterns. They sniff the sidewalk, investigate a bag brought into the house and revisit places that smell different from the last time they passed. A visitor brings a combination of smells the dog may not recognize. That is one reason an arrival can attract more interest than the same person receives after sitting in the room for a while.
A household can teach a greeting that gives visitors more space. Asking a dog to sit or wait on a mat creates a clear action it can perform. Rewarding that action when it happens gives the dog a reason to repeat it. A family can practice the routine with people the dog already knows before expecting the behavior around a new visitor. The consistency of the greeting helps the dog understand what to do when the door opens.
Owners can also decide how the greeting will begin. A person can offer the back of a hand for the dog to investigate if both are comfortable. A dog can be called away and given a toy or another activity if it becomes too persistent. It is easier to redirect the behavior early than to wait until a visitor has to push the dog away. A predictable response can make the exchange more comfortable for both the visitor and the dog.
Claims that an ordinary pet greeting reveals a medical condition go further than this behavior can establish. Research or work involving trained scent detection involves a task, training and controlled conditions. The behavior of a pet meeting someone in a hallway is a different setting. People with symptoms or a concern about their health can describe the symptoms themselves to a clinician. The greeting is best understood first as a common behavior in an animal that relies heavily on smell.
The practical question for most families is how to allow a dog to explore while giving people room. The usual answer involves a cue the dog knows, a reward for following it and an opportunity to greet the visitor once things are calm.
For a visitor who would rather skip the greeting, giving the dog a familiar task also lets the person enter and get settled at a comfortable distance.