I have heard it was an imbalance of some kind...that there was a product sold that was suppose to help, I cannot remember the name of it, so I am sorry. I would check with your vet, also check the amount of bonemeal content in the food you are providing. Someone once told me if you sprinkled bonemeal on sawdust a dog would eat it..sometimes if the content is too high there is a lot left in the feces. The only thing left to do is to pick up each day so there is nothing to consume. You might have your puppy checked for worms as well, they can cause a terrible gnawing hunger,especially if it is round worms.