Nutritional yeast is an inactive form of yeast that's also a complete protein - containing the 10 amino acids that dogs need.
Nutritional yeast is also packed with B-vitamins, including B12 (typically only found in meat), has an abundance of trace minerals and the powerful antioxidants glutathione and selenomethionine.
It also contains the carbs beta-glucan and alpha-mannan, that boost the immune system.
B vitamins have been shown to lift mood and appetite in people. They’re also water soluble so need replenishing every day.