My dogs are rarely left alone...I leave to drive my youngin to school (gone 5 min) and my dogs holler and cry until I come in and take my shoes off. They do this every single day, mon-fri....whether someone else is at home or not. Its only when I leave--nobody else.
Of course its come in handy when I've had unwanted house guests..and I'll stay gone for 10-15 minutes instead of 5. Heck-I'll sit in the driveway and enjoy a cup of coffee before coming back in