Preheat your oven to 350 degrees.
Prepare cookie sheet lined with parchment/baking paper

Mix first 4 ingredients. Add approximately 3 cups water, 1 cup at a time until dough pulls together. Place on a lightly floured surface and knead into a pliable dough.  Roll out to 1/4" thickness. Cut into desired shapes and place on cookie sheets lined with parchment paper. Alternately you can grease the sheets if you wish.

Bake for 15 to 20 minutes until firm and browned. Leave in oven to cool overnight or for at least 8 hours so the treats become hard and crunchy.

Storing Dog Treats
In general you should store dog treats the same way you would homemade people cookies.  That being said, there are two main variables that determine storage time - the amount and type of fat in the recipe and your local weather conditions.  If your recipe uses fats such as butter, or meat bits or juices then it will be more prone to rancidity than a recipe that uses some vegetable oil or shortening.  Your treats may mold or spoil much faster in humid or very hot climates. 

Refrigeration and Freezing -  Refrigeration will prolong the life of more fragile dog treats. Make sure to store in a tightly sealed container or zip lock bag.  You can also freeze most treats in zip lock freezer bags.  Allow to thaw completely before use.