Here's one that friends of mine have changed many times over the years. I've been making it for about 25 years now, and everyone loves it!! (well, the dogs, that is!!)
1 3/4 cups whole wheat flour
1/2 cup cornmeal ( that's for our southern friends)
1/2 cup uncooked oatmeal
1/4 cup rye kernels
1/2 tsp garlic powder ( or just chop some raw0
1/2 tsp salt
3 Tbsp dessicated liver powder ( this is gross stuff I get at the health food store, I usually add a bit more)
1/2 cup meat drippings ( bacon etc) or shortening
1/2 cup of your best stock ( don't scrimp just because it's for the dogs)
Combine flours, etc and seasonings. Add meat drippings. Blend until mixture resembles oatmeal. Add egg, and enough stock to form a ball. Knead dough for a few minutes. Roll out 1/2 inch thick. Cut, using your dog bone cutter. Place on oiled backing sheet, or just parchment paper. Prick with fork. Bake at 350 for 25 to 30 minutes. Cool on rack.
Throw one to the dogs as a treat,then store in airtight container.
When I made them on a regular basis, even buying the liver stuff etc, it was waaay cheaper than buying them. And it was fun.