You simply need flour, baking soda, peanut butter, oats and carrots. I'll add the recipe down below.
Some people say, dogs shouldn't have peanut butter. I use unsalted peanut butter, and my dog goes crazy when I have one of those dog cookies in my hand. I mean, I am not a vet, but that little dog treat made of simple ingredients can't be unhealthier than what is mixed into regular dog food (gelatin, artificial flavors, thickeners, ...).
As I said, our dog gets a vegan dog food, the brand is Natural Balance. I add a link if you are interested. In my opinion, dogs can digest everything, and I'm sure that they get all the nutrients from that vegan formula - that we usually feed with rice and veggies. In fact, her breath smells way better since she is on the vegan formula, than when she was fed the non vegan dog food with turkey and beef. Just logically I would not feed a cow to my dog, because she wouldn't be able to hunt and kill a cow. I think the cow would be able to protect herself and kill the dog if she had to.
In my opinion, a cat can't be fed vegan (just as a side note) - some people do it and they say it works. Thankfully I don't need to think about that.
Also, as the dog is still hunting rats every once in a while, I wouldn't call her a "vegan" dog. She is plantbased, everything else is up to her. If she catches a rat, she can eat the rat. But most of the time she doesn't even want to eat the rat after catching it.
Here the recipe, try it out, no matter if you have a vegan dog or not. It's a simple and delicious cheap homemade snack that helps you get your dog's attention during a walk or a hike. 

Ingredients:
1 cup flour
1/4 cup oat flour (simply blend oats until they are flour-like)
1/2 tsp baking powder
pinch salt
1/3 cup peanut butter unsalted
1/2 cup grated carrots
Instructions:
Preheat the oven to 350°F. Prepare a cooking sheet with parchment paper.
Simply mix everything together in a big bowl. It needs to become a slightly sticky dough and hold together. If it doesn't hold together, add a little bit more peanut butter (or water) and it its too sticky, add a little bit flour or oat flour.
Form little bits your hands and place them on the cooking sheet. Depending on the size of your dog they can be smaller or bigger.
Bake for 10 minutes (depending how small they are, they will be cooked faster). If the bottom of the cookies gets brownish, they are done.
Let them cool down completely before giving them to your doggie.