Where can I find psychological testing center for dogs in the northern virginia area?

Check with your local animal hospital for clinics. Also try your county animal shelter as they often test for these things before adopting them out. It could be that she has loss of hearing, or an eye disorder. If she tries to bite when taking a pig ear, or a good bone away then she really ought to be put down. If you got her from a shelter, take her back. Not all dogs can be saved. If she does lose it and bites someone she will be put into quarantine, during which time you will be forced to pay boarding costs until the judge gives his decision whether to put her down or not.