Dogs always want to follow their owners and once they realize that their humans are going out without them, they will almost always look glum and even heartbroken. Do dogs miss their owners when they leave? This video by Brain Craft offers some interesting answers.
Dogs use the smells, sounds and other sensations provided by humans to distinguish one person from the other. When a dog smells a familiar human, there is a specific area of its brain that is being triggered, which is associated with positive expectation and rewards. So when that familiar person leaves, all the good things are also gone. A lengthy separation is a great loss for dogs and this could lead to serious anxiety problems.
It is still unclear if dogs are able to determine the length of time they are left alone though. According to the video, a study found out that after 2 hours, dogs greeted their owners with more intensity than after 30 minutes of being left alone. However, there was no difference between 2 to 4 hours. This means that dogs can tell the difference between 30 minutes to 2 hours but beyond that is still unclear. Further studies about this are still ongoing.