Does anyone know of a tried and true way to stop a dog from eating it's feces?

Poor Sarah!  Most of you know we got her as a breeder re-home because she has a heart defect (Sub Aortic Stenosis) and that she was overly crated for the first 3.5 years of her life.  I know this is where the habit began.

While we have overcome much, bringing in the occasional foster dog (usually if it is an adult or pre-adult female) seems to have caused a certain regression/anxiety.  Because of it I have had to be firm with my group in telling them I can only take males or female pups.

Sarah will eat her feces while in our 6' x 15' outdoor run, if she has an accident in the house (also part of the regression); and now sometimes even at night when we let her out if we don't call her right back inside...she eats then too. 

~Jonney