bathing small dog in cs

My tibetan spaniel (looks like a pekingese) has had allergies since he was a puppy. He's now 11 yrs old. He chews his feet until they're raw and I know that's food allergies . I've changed his food many time to no avail. He also has mold, tree, grass, etc allergies I've tried many, many otc products, creams as well as vet pharmas but nothing helps. He gets shaved every summer (Texas heat). I feel sooo sorry for him, he's always scratching. I haven't given him cs yet, (I recently bought some Utopia) but how much should I put in his water? I have several water bowls around the house and he shares his water with a boxer and an akita (bigggg dogs) and three cats. These are all inside animals. What about bathing him in cs or dipping his feet in it or just pouring some over him like a rinse? Thanks in advance. Tweet