Because separation anxiety deals with a mental disease rather than a physical disease and has many varied manifestations ( as discussed in the last article) it is often a lot harder to tie down the specific causes of it.
It is a form of mental illness and is higher in dogs gained from shelters. It is believed that dramatic changes in the dogs life, instability and lack of security can be major causes.
Changes that cause dog separation anxiety
Change of schedule ; Dogs like humans are creatures of habit, they crave routine and get to know the world well in a controlled environment where things are safe. In a wolf pack, wolves run and rely on each other, nothing unpredictable happens as they are the apex predator. You take a wolf, and evolve it down into a dog, and give it random events that it has to fit in, this is very often going to give you behaviour issues if not separation anxiety, where they don’t trust you to be home at a given time anymore. They don’t trust you to feed them etc
of house ; Like humans changing house or city is a big deal, For a dog it is much more so as it often means leaving their dog friends behind, familiar sights and sounds and all that made them comfortable in knowing that they could get around or that they were going to something familiar.
A well balanced social dog loves surprise walks in parks, but for a rescue dog that has never has stability, changing house and city can be traumatic and result in separation anxiety.
Change of members of the family
While dogs may not interact with every member of the family the same, they are a pack animal and know their place in the pack. some dogs seem to like all humans, but they need to evaluate if the human is a threat and where they sit in the pack.
If the dog loses its owner, it has lost its alpha and may take a long time to readjust. The smarter the dog, often the more sensitive they will be to this kind of dramatic change.