The correct term for eating poop is coprophagia and while it does occur very rarely in humans, this article is about the the causes and treatments for this problem when it occurs in dogs.
-Causes-
There are many suspected causes and if the problem exists in your dog, there may be more than one cause. It is more common in dogs than in cats, and anyone who owns both will note that cats are much more fussy eaters, often smelling things first, where a dog simply wolfs things down.
The feces of any omnivore, or carnivore, contain some undigested protein, this is very attractive to a dog, who is essentially a scavenger, so eating something they find lying around that smells yummy, isn't terribly unusual.
Next we must remember dogs are protective of their den area, leaving something like that lying around might attract other predators, so they gobble it up as a primitive behavior. Mother dogs eat the feces of their puppies as a way of keeping the den clean and odors down. In contrast urine is used to tell other dogs to stay away, as urine is not a possible food source.
Also, in the wild, mother dogs who have eaten, return to the den, and vomit up the food for the pups to eat. Feces, in many ways are similar to regurgitated food, especially when fresh and warm.
Sometimes the behavior is learned as a pup, from watching mom.
Sometimes the behavior forms as a puppy, particularly if living in a situation that often lacks attention, such as in puppy mill pups, ones that are sold through the Pet Store system.
Poor house training often contributes to the problem. When a person house trains a pup correctly, they should go outside with the pup and immediately offer it a soft treat reward for defecating outside. The owner then uses this time to clean up the mess, and the puppy develops the behavior of looking to the owner for a reward rather than turning around to see what came out of it.
Dogs who are disciplined for messing indoors, by having their face put in it might resort to eating their feces as a way to avoid a punishment, or because they think this is what their owner wants them to do.
Similarly sometimes dogs get attention for this behavior, thus reinforcing it. This is because dogs love attention and often have a hard time distinguishing between good attention and bad. This would be especially true of a dog who gets very little attention on a normal basis and may only get attention when it does something we would consider bad.
Dogs who are stressed often resort to this eating their own feces, perhaps it is comforting in a way, nobody is sure.
Being fed too much of a good food may cause this problem. Good foods contain more protein, and it is the protein in the poop that makes it so appealing. Since the food contains more protein, a dog does not need to eat as much as when they are on a lower quality food, but most owners who make a switch to a better food, still feed the higher quantity of food, as such the dog cannot digest it all properly, and a good amount of it is undigested in their feces.
Being fed a food with a high fat content. Fat adds flavor to the food, and it also makes poop taste yummy.
Dogs who are fed more canned food, and less dry food, are more likely to have this problem.
Dogs who are fed only once per day, may feel the need to eat something later in the day.
Various health problems that interfere with digestion contribute to the problem, again because the dog is not digesting all the protein.
-Myths-
The biggest myth is that this problem means the dog is not getting enough vitamins and minerals in his or her food. If the dog is not getting enough in the food, there certainly will not be any more in the poop, so this myth is not correct. While it may be true that the dog is not getting enough vitamins and minerals, it is not a real cause of this problem.
-Treatments-
Proper potty training right from the start is one of the best steps to avoiding coprophagia altogether. Make sure you are armed with a soft treat reward and go out with the dog every time, and offer the treat immediately. Eventually the treat might even be a verbal one, Good dog or a pat on the head, but you want to make sure the treat never becomes the doggie doo.
If a dog messes in the house, it is usually the result of human error, the dog was not being watched. Or it might be a sign of a health concern, either way, do not put the dogs face into the mess.
Monitor your dogs weight and diet. Most dog foods provide feeding instructions on the bag based on the weight the dog should be. Make sure you follow those guide lines and adjust if needed based on your dogs metabolism. Break the feeding up into two or three feedings a day. Smaller dogs often require more feedings throughout the day than do larger dogs.
Have a vet examine your dog for health problems such as pancreatitis, worms, or other problems with digestion of food.
Adding meat tenderizer to a dogs food tends to reduce the amount of protein left in the feces.
There are many products available at pet supply stores which may be added to the food prior to being eaten, and they are designed to change form after being defecated so they will make the poop taste bad.
Canned pineapple when added to a dogs food is also supposed to alter the taste of dog feces.
Putting Hot, or Tabasco, sauce on the dogs poop will discourage the dog from eating it after a few experiences, but this is as much work as simply keeping the yard clean anyhow, which would eliminate the problem right away, no poop = no problem.
Getting the dogs attention immediately if the behavior is observed is a good thing to do, call the dog, or shake a bottle with rocks to break his, or her, train of thought.
Putting a muzzle on the dog when putting him, or her, out may just help break the cycle too.