Same with my dogs.
If the word "corn" appears in any form, it doesn't come here.
[soy, either]
One of my Ibizan Hounds was so sensitive to corn it actually made him manic.
Taste Of The Wild makes the best stuff.
Mine like the High Plains Bison/venison blend and the salmon/fish blend.
I don't think they should live completely on meat because dogs are truly omnivores so I mix it with a feed Tractor & Supply recently started selling called "4Life".
The chicken-based small bits formula is really good.
Is the food you use available online?
I can only get Purina special order, otherwise I'm stuck using some kind of rat Chow analogs available at the local pet stores.
[which still beats that corn junk food]