Hey,
Cat!
I don't have any experience with a dehydrator, but if I had one, the very first thing I'd make are dried
unsweetened cranberries!!!

I cannot find them anywhere!!! I tried making them in a low oven, but they came out pretty crunchy.

They'd be fine in baked goods, but you can't really throw them in salads and such as they don't have the right texture.
I think I'd be really tempted to dehydrate lots of fruit without sugar---oooh, like cherries!

Crispy veggies do sound yummy...I tried making zucchini chips in the oven, but they turned out soggy.
As for your poor puppers, I'm no expert (by far!), but have you taken a look at Dr. Pitcairn's book,
New Complete Guide to Natural Health for Dogs and Cats? The dog we had when I was a child had terrible allergies. My mom ended up having to make all her food. At one point, she lost all her fur (and she was a shih-tzu!), but with the home diet, she got much, much better. Dr. Pitcairn has several wonderful recipes for diets for those with allergies and explains how to reintroduce things to isolate what, exactly, they are allergic to. It's fabulous. Just a thought...
I know it must be really hard to do all the extra work and just as tough to see your pup suffer.

I hope it all works out and soon!
Loriann, rawhides can be dangerous if a dog gets a small piece lodged in his/her throat. However, we feel that as long as we're in the room with the dog, we can do something about that, should it ever happen.

The books I've read say that the very best thing for a dog to chew on is actual bones (sturdy ones, not things like poultry where they can splinter). In lieu of that, you can use Nylabones (they're great and last forever...plus they're safe enough to leave with the dog all the time), consumable chews (like Nylabone's "Healthy Edibles" or "Velvet" Booda bones), or rapidly consumable things like Greenies (which have been reformulated and now are very digestable).