That is wonderful about your dog and the castor oil. My Mother also told me the same thing about castor oil and having to take it as a child. She said they were hesitant to tell their parents they had a stomach ache, because a spoonful of castor oil was always the remedy. :)
I saw a very interesting post awhile back regarding castor oil and a woman flattening her belly with it. Not sure if this would work on every bloated belly, but it was a very interesting post. Here it is: