As for flour I was given advice on homemade dog treats. Using bleached white flour is not good. You can substitute white flour with potato flour or rice flour. That would be much better than the white. 
In my area I can find specialty flours of all kinds made by " Red Mill " ... just a brand ...
EDIT: Another maker of specialty flour - www.old-mill.com/ ..... not sure about corn meal?
I did find this of interest concerning the corn meal and dogs ...www.best-dog-treat-recipes.com/ ... and searched " cornmeal treats "
In my area I can find specialty flours of all kinds made by " Red Mill " ... just a brand ...
EDIT: Another maker of specialty flour - www.old-mill.com/ ..... not sure about corn meal?
I did find this of interest concerning the corn meal and dogs ...www.best-dog-treat-recipes.com/ ... and searched " cornmeal treats "