Dog suffering from separation anxiety?

Hi - I am a very experienced dog owner. I adopted a dog from a shelter a year and a half ago that suffers from separation anxiety. Before me, she was adopted for less than a day and returned because she was inexperienced and couldn't handle her. She is "unadoptable" for most families. Her tempermant is exceptional other than that - very sweet, mellow and she has become a great companion for my other dog. Her separation anxiety is so bad that she has eaten her way through a wire crate, plastic cargo crate, ripped the crate tray to shreds, moves herself across the room while in the crate and slobbers so much that her whole body is wet. I've tried every possible invention available to help her. I've taken her to a behaviorist that costs $250 an hour. She put her on Xanax and is now on Prozac. It helps but she still slobbers. Every day there is a pool of drool in the crate. Does anybody else have this issue? Have you ever been able to take the dog off of meds and what worked for you