What Are The Side Effects Of Coprophagia In A Dog?

Thanks for your responses. The dogs owner has been out of the country for several months and is expected to be back home in the next month or so. His dog has enjoyed our company as well as the company of our two dogs when we are able to bring them over with us. He gets fresh water everyday and as I stated previously an hour to an hour and a half of attention almost daily. He is left in a large fenced back yard and has shade from the sun. He did have a problem with fly strike on his ear tips, but is responding well to ointment prescribed by the vet. He is a sweet dog and very loving. He is not displaying traits of severe isolation, that is to say he is not aloof or withdrawn or aggressive around people. If his behavior were to show this, I would bring him to my home and I feel he would be able to have a speedy recovery. His ex-mama (neighbor's ex-wife) stops in about every third day and over feeds him and we have to dump about 2-3 cups of food back into his bag. We have been regulating his intake to about 2 to 2 1/2 cups of dry food daily.
 Again, I have to mention that his eating of his own feces is what seems to of concern right now and have been told that it is a very hard habit to break. As it is only his fecal matter, I am unsure of the parasitic content, but it can't be healthy.

We have two pugs, 4 and 2 years of age.  The younger one has this same problem -- she'll give you about 10 minutes to clean her mess up (putting it in plastic bags out in the yard, or flushing it away if she uses a doggy pad in the house), while she walks around anxious to have it gone.  If no-one responds or sees it, she will "clean it up herself" -- she's like a one-dog cleanup committee for fecal matter and vomit (and YES! -- it grosses us out to no end).  We asked the vet what we could do, and what are the harmful effects of this.  She told us that the worst case scenario is the pup eating OTHER animal feces (outdoor animals), because they're usually loaded with parasites.  We have also tried sprinkling her food, the older dog's food, and the cat's food, with Accent -- which has been shown to be very effective in some dogs with coprophagia.  Isolation will probably not do much good -- it's natural for animals to clean up after themselves to throw off predators on their trail.  I would start using the Accent on the dogs food, and then watching to see when he goes potty and use a plastic sandwich bag or plastic grocery bag to dispose of the fecal matter before he can eat it.  Also, the vet told us that sometimes there is a vitamin or mineral deficiency that the dog has that will cause them to do this.
Sounds like the dog needs some extra loving.  Isolation is so hard on them emotionally when it's over a long period.
Hope that helps out some!
Moe