If your dog has always been, for lack of better words, a ‘licky dog’ then it may just be a normal behavior for your dog. If it is a new behaviour, there can be underlying medical or behavioural issues to address.
Some dogs just tend to lick more than others, and this usually includes licking the air, their lips, objects around the house and quite often your face! As with any behavior, if it is undesirable to you then remember the golden rule of ‘IGNORE unwanted behavior, REWARD wanted behavior’. You can find more info on training your dog here.
It is also worth mentioning that while behavioral causes are possible, one study found them to be a less likely cause than a GI abnormality. Anxiety can lead to obsessive compulsive disorders and air licking can be a symptom.
Abdominal or Gastro-intestinal pain
One possibility, is pain from a gastro-intestinal/abdominal abnormality. Such abnormalities can include pancreatitis, inflammatory bowel disease, gastric foreign body, ulcer, or other cause of abdominal or gastro-intestinal pain. If your dog also has diarrhea and/or is vomiting, this increases the likelihood of abdominal or gastro-intestinal pain being the cause.
Oral Issues can also lead to air licking, such as dental disease (usually severe) or something stuck in the mouth, for example a stick (check the roof of your dogs mouth if they are amenable to this as this is a common place of stick lodgement).
Air licking can also be part of a seizure complex and may indicate an underlying neurological problem, for example epilepsy, other disorders affecting the brain.
What should I do if it is a new behavior?
If you are noticing this new behavior and are unsure about the cause, it may warrant a trip to the vet. Before going to the vet, it is a good idea to take a video recording of the behavior and note down anything that might be causing the behavior. For example if it is right after the dog eats, and recording a short video of the behavior. This could be helpful to find the underlying cause and it is often difficult to show the behavior to the vet in the exam room.