Canned sounds like a wonderful idea! Others here have had success with cream cheese, liverwurst, hot dogs and my personal favorite is Pill Pockets. I read somewhere, and Dallas' actions confirm, that the odor of the meds is what turns the houndies' stomachs off. So if you can handle the pills with tweezers and not your hands, you can form a meatball out of the canned or "whatever works", punch a hole, drop the pills in with the tweezers, seal it and go for it.
Good luck! IMHO: I would be skeptical about the dx................do you have a copy of the bloodwork? Are there plans to repeat? I can see where a vet would make an observation like "This condition is similar to what has been seen in cases where dogs have been exposed to .................", but with your squeaky clean house and yard, I would be demanding another explanation.