You might have already done this - so please disregard if you have - but...
Have you tried him with a kong when you go out? I noticed that the small puppy kong wasn't big enough to keep harvey occcupied whilst I was out - so I got a standard sized kong. First step is to "plug" the little hole in the end (I use peanut butter or cream cheese) then I put the kong, small hole down into a mug. I then fill with chopped up carrots and hotdogs - then pour in some chicken bouilion (sp) - the kong in cup then goes in to the freezer. Then, about 3 or 4 mins before I go out I put the kong into the pen (Harvey outside the pen) - Harvey goes nuts to get in to his pen to eat the kong. (he really picked up on the Kong = yummy very quickly.) I then put him in his pen and leave the house without saying a word to him.
This started the process of him becoming really happy to be in the pen while I was out - he had something to occupy his mind - and, as it's a big kong, and he has to wait for the melting process, it takes him an AGE to get through it! By the time I'm back home, he's worn out trying to figure out how to get the frozen treats out the kong and is fast asleep (kong completely empty!!), and it seems he now doesn't even notice I'm not here (except for a few barks). I have to say, this took about 5 days or so to get him used to it. But, following the same routine every day, he really picked up on it. I also have the DAP diffuser diffusing all the time and a little radio in the backgound.
What I have now are a number of kongs and I do the filling and freezing in one go!!
If you haven't tried this - please do - it might just work!
If the SA is really deeper set - Odie might need to have some help from a behaviourist, as I understand if SA is a major prob, food aversion techniques might not help. But...give it a go...please let us know how you get on. Will be thinking of you.

p.s - when putting the frozen kong in the pen -try a splodge of peanut butter or cream cheese over the larger hole - it gets that licking process started, so the melting starts too!

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