Barking at nothing

Dogs have highly developed senses. So, even though it seems like they are barking at nothing, there probably has been a disturbance in their environment to trigger such behavior. 

A dog barking at nothing may be because they perceive sounds and movements far away or too subtle for humans to notice. Their instinct is to alert and protect their pack, so they will try to communicate with you if they notice anything. 

Of course, sometimes they are just bored, anxious, or in discomfort, so evaluating their overall behavior is essential. Barking at nothing may also be a common behavior in older dogs and doesn’t indicate anything serious.