For me however, I feel that while dogs ancestry goes back to wolves who do not eat much grain. Dogs have evolved over the centuries and changed. In owning a dog, my opinion is that dogs love their meat (well, and peanut butter) they will eat anything when they are hungry. And my guess, however uneducated it might be in the field of wolves, is that if they were hungry, they would eat whatever was available too.
In conclusion, it's totally up to you.
Just a little side note about the peanut butter. My kids and I did a little experiment one day. Mind you, it totally was in fun with a side of serious. We put a piece of meat on the floor and a few feet away we put a glop of peanut butter about the same size to see which one she would go to first. She smelled the meat first but did not eat it. Ate the peanut butter and quickly went back to the meat. What did we prove? Even dogs eat dessert first.
Unscientific but yet delicious
Printable recipe here.
1 1/2 cups unbleached flour
1/2 cup wheat germ
1/2 cup pork fat*
1/4 cup crunchy peanut butter
1/4 teaspoon garlic powder (yes, the verdict is out on that too)
1 large egg
1/2 cup cold water
Mix all the ingredients together. Shape into logs and press flat. Bake at 350F for 20 minutes. Remove from oven, flip the treats. Place back in oven. Turn oven off. Leave treats in oven until it cools. This will dry them out so they are crispy to eat.
Dog Food Advisor article: Are Dogs Carnivores or Omnivores?- by Mike Sagman
The Wild Side: Are Dogs Carnivores or Omnivores? by The Wild Side Blog
Are Dogs Carnivores or Omnivores by Marks Dog Blog