For mild separation anxiety, leave an item of clothing containing the owner's scent, downplay departures and arrivals, or use an over-the-counter remedy. Try a safety cue, which is a word or phrase that reassures the dog of the owner's plan to return, says the Humane Society of the United States.
For severe anxiety, the Humane Society recommends using desensitization training. Train the dog to sit and stay, which reassures her even when you are in another room. Contain the dog's anxious behaviors in a safe space, such as a spare room; a room with enough space to move around, a window, a few pieces of laundry with the owner's scent on them, and a couple of toys is ideal. A veterinarian can also prescribe calming medication, states the Humane Society.