Have you had her medically checked out? I'm not talking about a quick vet check. I'm talking about a complete workup so you can rule out Cushing's, adrenal problems, hypothyroidism, liver issues — all of it. Once you get a medical clearance, you can proceed with the other suggestions, but be sure to do that first.
Next, is boredom an issue? Sometimes low-grade stress coupled with boredom and inactivity produces a chowhound. Dogs are social and thrive on companionship, and even though you have another dog, if your Pomeranian still feels lonely, you may see displacement behavior, which manifests itself in such things as excessive licking/grooming, barking, pacing, and, drum roll...eating! To solve this problem you have to enrich your dog's lifestyle with more exercise, increased interaction (in the form of training — my favorite subject!), decreased time spent alone, and a rotating offering of "smart" toys.
As for the stool-eating issue, I've found that high-fiber, weight-reducing diets can increase this problem. Changing your dog's diet may be a solution, but only your vet will be able to tell you for sure. Ask his or her opinion before making the (gradual!) switch. Also, some people have luck using Forbid powder on their dog's food — it's supposed to make poop taste bad. (I know, it should already, but they're dogs!) If you try that, be sure to put it on both dogs' food, because with coprophagia (the consumption of feces), any poop is a potential target.
In addition, a "red alert" mentality has to be adopted by all involved. When either dog defecates, it must be immediately cleaned up to prevent the possibility of a regression. To change a behavior, the cycle has to be broken. (I'm preaching to the choir, I know.)
Reprinted with Permission of Hearst Communications, Inc. Originally Published: Why Does Your Dog Overeat?