OATMEAL SHAMPOO: 1 cup of old-fashioned oats; 4 cups of purified water; cook the oats in the water until they are gooey. It used to be that you could soak the oats for 3-4 hours or overnight and the water would be gooey; however, I have noticed now that oats aren't the "old-fashion" ones they were years ago. I have found that I now need to cook the oats until gooey; let them cool and just use the whole gooey mess, oats and all. I haven't seen a problem with the oats going down the drain just fine.
Wet your animal down just as if you were going to give him/her a bath; then apply the gooey oats all over, especially in all the irritated areas; gently massage him/her for 5 minutes or more...or as long as s/he is enjoying it. Then rinse thoroughly; then rinse again. Towel dry. Do not use a dryer.
You will be able to tell how soothing it is to your animal by the softness of your own hands after giving him/her the bath. You will have to make this up each time because it will sour and spoil. So if 4 cups is more than you need, then cut the recipe in half, or if you have a large dog, you may have to prepare even more.