1) A dog is not allowed to learn “alone time.” This is usually the result of a member of the family constantly being with the dog or taking the dog with them whenever they leave. Dogs need to learn how to be alone. This alone time training should begin immediately when you get your dog or puppy. Most people get a new dog or puppy and plan to spend an entire weekend or a week’s vacation consumed with making the dog feel “part of the family”. This is all well and good, but you must allow the dog to be alone. Start out by crating the dog and leaving the room for 5 minutes. Do not return unless the dog/puppy is quiet. If you return when the dog or puppy is barking, whining or crying you have just told the dog that behavior works – it gets you back in its sight. The dog is now controlling your goings and comings.
Begin extending his alone time, incorporating actually leaving the house for extended periods of time. Do NOT make a big fuss when you either exit the house or return home. Departures and arrivals needs to be low key so you dog does not attach any “special” meaning to them.
2) Another factor in dogs having separation anxiety is lack of structure in the home. Dogs are very much like children, they do very well when they know what is expected of them, the rules never change and they need to say “please” for the things they want that have high value. Basic obedience such as simple sits and downs can work wonders in adding structure and leadership role into your relationship with your dog.