homemade oatmeal shampoo for dogs...1 cup oatmeal, 1/2 cup baking soda. 1 quart warm water In a food processor or coffee grinder, grind oatmeal until it’s a flour. Pour it into a bowl, and stir in the baking soda. Add the warm water and stir until well incorporated. When you’re ready to use it, get your dog wet. Lather her (or him) up with the oatmeal shampoo and allow it to sit for 5 minutes if possible. Rinse off, dry, and give your doggy some snuggles!