After spending several hours in front of computer and looking in the holistic pet care books that I have, I make the decision to do what other lab owners have done and try a limited ingredient petfood. I chose Wellness and went to petstore to get some. Oh my. Sassy will need 5 cans of moist food a day! And these aren't small cans. Make decision to buy Wellness limited ingredient kibble also. I'll transition her over the next few days, as well as making sure she can't get to any of the cat food (which I'm sure is one of her allergy triggers, but she's a sneaky dog when it comes to eating catfood and the occasional kitty crunchy).
And after we got home, I realized I hadn't gotten any more moist catfood! At least we have several days left of that, so I've got some time to figure out exactly which one they're getting until I get my act together enough to cook for the critters.