Dog freaked out, now terrified at sporadic times

Question
I searched through your database of questions so as not to ask the same one, but couldn't find a similar situation. My Irish wolfhound/standard poodle mix is 6 years old, and a sweet gentle boy (leash aggressive but we've been training and he's getting better). He has always disliked being along (whimpering when I come home, chewing the occasional shoe) but nothing that was horrible. Sunday two weeks ago we went to a Superbowl party for about five hours. Came home to a very calm dog and an irony smell in the house. Turned on the lights and he had destroyed one corner of my home (exterior wall of guest bathroom, guest closet and guest bedroom) Pulled everything out, chewed the boxes holding things but not what was in it, ripped the dress bags holding formal wear but didn't damage the clothes themselves), tore blinds and broke a picture frame, resulting in stitches and a ton of blood lost. Climbed into the bathtub (I think to get at the skylight judging by the bloody paw prints), the windows, the exterior wall of the closet. Didn't go near the front door, back door or other windows. The vet said separation anxiety, and gave me anti-anxiety meds. Tried to leave him once and he started trembling so hard he could barely walk. Yesterday afternoon, as I'm standing doing dishes and my boyfriend is reading the paper, he starts shaking again, though not as badly. My shoes weren't even on! He's had a couple of weird moods, where he stays very close to my boyfriend, won't listen (to me or him), hovers at his feet, etc. My boyfriend likes him but by no means is he best buddies with him, they tolerate each other. It's weird clinging on to him. I haven't left him alone in two weeks. I'm lucky in that I work from home, so he runs errands with me. Obviously not a long term solution. Up until two years ago, he was always living with another dog, and while I know he dislikes being alone, he visits on the weekends with my mom and her dog, goes to the dog park and on walks, etc.

So I've probably explained way too much, but is it possible something just scared him? I've really been wanting to get another dog (my boyfriend doesn't). Would this be a good time to try and see if that improves him or is that not a real fix? I just can't tell what's triggering him...we have squirrels and (I think) raccoons on our roofs occasionally, but he's never seemed to care.
Thanks for taking the time to read this...any ideas are appreciated.

Answer
Your dog really requires a hands-on, in person evaluation by a credentialed behaviorist.  His destruction and attempt to claw through walls/skylight is classic barrier frustration, but his other behaviors suggest a strong conditioned response to something that occurred when you weren't at home.  Scent (not just sound alone) can trigger this response and your dog might be scenting AND hearing something going on in your home (or on your roof or in your attic) that you can't smell or hear.  Your veterinarian was far too quick to give meds to this dog, I'm hoping s/he did a full neurological checkup first.  The classic treatment for serious separation anxiety involves a beta blocker (propanolol) which should never be given without serum (blood) checks and careful physical followup (beta blockers affect heart and blood pressure).  I suggest you do two things: one, find another veterinarian for a second opinion; and two, try to locate a credentialed behaviorist (NOT a dog trainer with make believe credentials) to "interview" your dog and ascertain temperament while attempting to determine what, in his environment, might have precipitated this crisis.  Until then, try not to leave this dog alone without serious confinement (bathroom or kitchen with strong gate) for too long and DO NOT get another dog!! Introducing another dog is not wise for many reasons, not the least of which is that dogs will sink to the lowest common denominator in behavior (meaning BOTH dogs can end up with this problem!)  Also, every person in the home really needs to want an animal companion and your boyfriend clearly does not.  I have an extensive and complex behavior modification program for separation anxiety but I'm not 100% convinced this is a classic case.  Do what I suggested and re-post if you can't find an expert.