How To Give A Dog A Oatmeal Bath. Slowly mix the oats into the water until the water has that milky, suspended appearance that you observed in your test glass. Use ½ cup for medium to large breeds.
Here's what you'll need to create a homemade oatmeal bath for your dog: Add one of these options to boost the moisturizing. After you have massaged the oatmeal into your dog’s skin and fur and let him soak for 10 minutes, rinse the mixture off with warm water.