I have heard that one of the reasons dogs eat their own feces is when they are not getting/digesting the nutrients that they need (so they eat the poop because it smells like it still has essential nutrition in it). A vet visit might be in order.
"Medical problems are a common cause, including pancreatic insufficiency or enzyme deficiency. Intestinal malabsorption and GI parasites are also common medical reasons that can prompt a dog to eat his own poop."
Why Do Dogs Eat Poop?
Ralphie - GSD, rescue, Gotcha Day 2/10/13
Nightshade - born 6/3/2003 - Domestic medium hair/Maine Coon mix (feline)
James - Domestic short hair (feline), rescue, Gotcha Day 6/23/11