It is not unusual to see a puppy eating its own or other's feces. This behavior actually has a name. It's called 'Coprophagia'. It is disgusting but usually not harmful if the puppy is eating its own feces. Nevertheless, it's the last thing you want to smell when you are snuggling with your puppy. If the puppy eats the feces of another dog or animal though, it could be harmful if the stools have worms, parasites or infectious diseases in them.
A simple training method can also be tried. When you are walking your dog on a leash, simply jerk the leash when your dog approaches feces, and reward him/her when they avoid it.
Deter - Coprophagia Treatment Sold By Amazon is described as "a safe and effective easy to feed chewable tablet. It is used to stop dogs and puppies from consuming their own feces. Dog eating poop (coprophagia) is a common but disturbing habit in dogs. The cause of this behavior is unknown, but this product is formulated to stop this." For-bid Stool-eating Preventative Sold By Amazon.com is described as 'Stop stool eating with FOR-BID. Pets eating stool is known as coprophagy. Vegetable protein and sodium glutamate work in the digestive system to give stools a bad taste. Directions: Simply sprinkle on dog food.'