Jenn, From what I've read on different forums is that Solid Gold and Natural Balance have their own processing equipment. So there shouldn't be any cross contamination to worry about.
Here's the list I have of what's made where...
Blue Buffalo: Canned foods made by American > > Nutrition in Utah. Dry foods made at CJ Foods in Kansas.
Breeder's Choice: Canned diets made at Menu Foods, but have not been recalled.
Canidae: Canned food packed by Evangers. Kibble made at Pied Piper in Texas.
Canine Caviar: Canned food made by American Nutrition in Utah. Kibble made by Pied Piper in Texas. Canned diets are 100% meat, contain no grains.
Castor & Pollux: Canned diets made by Menu Foods but have not been recalled.
Eagle Pack: Canned diets made at Menu Foods but have not been recalled and do not contain Wheat Gluten. Dry diets made at their own plant in Mishawaka, IN.
Evangers: They have their own cannery.
Go! Natural (Petcurean): Canned diets made at Menu Foods in Canada but have not been recalled.
Merrick: Has their own plant for all products.
Natura (Healthwise, California Naturals, Innova): Canned diets made at the South Dakota Menu Foods Plant but have not been recalled. Dry diets are made at their own plant.
Natural Balance: Canned diets made at American Nutrition in Utah. Dry diets are made in Diamond Plant in Sacramento, CA.
Nature's Variety: Canned diets made at Menu Foods but have not been recalled. The canned diets contain not grains. Kibble is made at Pied Piper in Texas. Raw diets are made in an in house plant in Lincoln, Ne.
Pet Promise: Purina Brand ... canned and kibble made in their plants.
Solid Gold: It is unknown where canned diets were made. Kibble is made in the Diamond Plant in Sacramento, CA.
Timberwolf Organics: Just released one canned diet and working on additions, it is unsure where this is made, but due to the size of Menu Foods I highly doubt it is being done there. Kibble was at one point being co-packed somewhere in PA but I've heard rumors that it is now being made out of the Diamond Plant. I cannot confirm this and the company will not give out information.
Wellness/Old Mother Hubbard: Canned diets made at Menu Foods but have not been recalled.
Wysong: Canned diets made at Menu Foods but have not been recalled. Most of their line of cans are grain free.
Edited to add this list was put together after the first recall from the tainted wheat. But I kept it because it showed where the foods were made.