I watched a show about this not too long ago. This guy lived in an apartment and apparently his dog whined and barked from the minute he left for work in the morning until he arrived home at night....neighbors were complaining and he was frustrated because when he opened the front door he was literally attacked by this 95 pound lab...lol. So, the dog trainer, asked him to set up video camera's in the apartment just see what happens....the guy goes about his business, getting ready for work, and the dog follows him from room to room desperately wanting his attention, which he never really gets. When he's ready to leave he kneels on the floor by the front door and pets him, plays with him for a few seconds and then gets up and practically squeezes his way out the door....of course the dog then cries, missing him terrbly.
He was then asked to try something different. He was asked to take a few minutes when he got up to give his dog some positive attention, and then just before he leaves for work, to bring the dog into another room and either offer him a bone or a treat of some sort. Apparently when your pet doesn't see you leave, hes fine while you're gone. Later that evenng when he checked the tape, the dog finished his treat, walked around the house for a bit and then just sprawled out on the floor and went to sleep. He didn't bark or cry all day and when his owner arrives home at the end of the day, he opens the door and has to call for his dog to come....hes playful but nowhere near as hyper and upset as he was before....so everybody is happy.
I do this with my Lucy and it works......I dont have cameras hidden around but I've been told that she doesn't cry when I leave, she just lays on the sofa and goes to sleep.
She looks so cute laying there...lol