[header] How to make an oatmeal bath for a dog [title] Grind a cup of plain oatmeal into a fine powder. [step] Grab some plain, raw oatmeal without sugar, fruit, or other flavoring additives. Use a food processor or coffee grinder to blend a cup (240 ml) of it until you've created a fine powder. 
[substeps] The powder will dissolve in water better. [title] Place a non-slip mat in your tub.