Once you are your rescue dog's accepted Pack member (not necessarily accepted Pack leader), your dog may more readily feel Separation Anxiety upon your leaving than a non-rescue dog would normally feel.
Understandably: After feeling lonely if not left behind for some time, the dog finally found you or was found by you, grew attached, is now left alone again and so the dog must feel that (s)he may have been left behind again. Your dog can't know that this time it is different: You're simply off to work, or grocery shopping or whatever.
Be aware that Separation Anxiety has dog behavior, dog health, and dog care implications:
- Dog behavior: For example, having a panic attack means your rescue dog may destroy house inventory without even wanting to! Thus scolding would be detrimental: your dog wants to behave well (if trained well) but a panic attack changes dog behavior as much as people behavior!
- Dog health: For example, having a panic attack means your rescue dog feels enormously stressed, and if that's repetitive then the frequent stress will drastically impair your dog's health (at first the immune system and the integumentary system: more sick in general and skin issues in particular).
- Dog care: For example, having panic attacks means that you will have to make your house extra dog-proof. Otherwise you would have to lock your dog away which never is a genuine solution - and here, it will worsen the Separation Anxiety!
So you see there is ample reason to avoid Separation Anxiety issues with your rescue dog from the outset. But what if this feeling of urgency comes too late and you are already facing a Separation Anxiety problem with your rescue dog?
With a rescue dog it is more important to steadily build up time of separation, progressively longer periods. Also, your dog will feel calmer (because less bored) when you provide his/her favorite SAFE toy before you leave. For this however you MUST first have checked your dog's play behavior with that toy and in general, because a dog with a panic attack (that's what Separation Anxiety is) might show his/her worst play behavior with his/her most favorite toy.
Similarly, even dogs that behave very well in the house while we are there, may become destructive when we are gone and they get a panic attack. It makes that a big difference, yes! Hence why Separation Anxiety has its own chapter in House Training Dogs To Behave Well, and why there is a long list of points to consider before you leave your dog alone for more than a few minutes - too much for a succinct "decision tree" like this here.
You may also want to take a look at our relevant dog care remedies here (scroll down to "Separation Anxiety / Relaxation").
Note that every key point raised above you can find more comprehensively explained in other places on this website. The menu is your friend. Here, links have been omitted only to keep this decision tree straightforward.
PLEASE NOTE: Posting a fragment of your overall dog problem in the comments below is not going to help. Provide complete details if you really seek the right solution. Of course we have a page for that as well: Dog Problem Consultation.