I came across a recommendation to add Dr. Pitcairn’s Healthy Powder to some vegan dog food recipes, so I thought I'd share it with you. Dr. Pitcairn wrote Complete Guide to Natural Health for Dogs & Cats.
Here's the page from the book that gives the instructions for making the Healthy Powder (click to enlarge)

The recipe isn't vegan, but here's a vegan version that I found on In the Dish.
- 2 cups nutritional yeast
- 1 cup (soy) lecithin granules
- 1/4 cup alfalfa powder
- 1oz flaxseed meal
