What are dog greetings? Greetings between dogs allow people to assess their own ability to handle stress, but that is of course not their primary purpose. Dog greetings serve a lot of functions in social species, from reducing uncertainty, fear and arousal to gathering information. They can be used to signal status and to increase tolerance for being in close proximity to one another, and may also be important in conflict resolution and reconciliation.
Source: A Guide to Dog-to-Dog Greetings