Hi and welcome to YT
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I volunteer 3x a week a a large no-kill SPCA shelter here in Phoenix. Personally, I think the way some dogs act in the shelter does not determine how they may act in a home where it's secure, quiet, loving, peaceful. For some dogs, the shelter environment is EXTREMELY stressful and it activates the heck out of them.
If this particular behavior did continue at home, I'd try something like the bark genie which is totally non-harmful but can startle them enough out of their bark trance.
At our shelter, we do allow "slumber parties" in certain cases so that someone can see how it go at home, prior to actually adopting. Is that an option for you...?