Hello, my name is***** and I have over 20 years of experience as a veterinarian. I understand that you are concerned that Shadow is eating feces.
Many dogs are drawn to eating feces. In most cases it doesn't mean that they are lacking any thing in their diet or that there is anything wrong with them.
The foods that we feed our dogs are so high in nutrition all of the nutrients aren't necessarily used and the stool may smell pretty good to your dog, not much different from food. Some animals, like rats and mice routinely eat feces as a food source if given the chance.
If she is highly food driven she simply finds feces as a treat.
It certainly isn't a great habit for her as it is a way of picking up with gastrointestinal parasites and introducing more bacteria into her oral cavity.
There isn't much that you can do about her habit except not allowing her access to stools. In highly food driven dogs (which Shepherds are) even a severe scolding or punishing her won't be enough to counteract what she feels is the positive reinforcement of finding food.
Products such as Forbid, which make the stool taste bad, can be used but this doesn't always dissuade all dogs or sometimes they only stop while on the supplement. You can try them, and they may train her well enough to stop for a while but this way be something that you may need to use on and off with her to reinforce the lesson.
Certainly if this is a new habit for her and/or she seems unhealthy in any other way it is worth having her veterinarian check her over and run some blood tests to make sure there isn't any illness driving her stool eating. I would defInitely recommend submitting several stools for your veterinarian to check for gastrointestinal parasites. In most cases this is a behavioral issue, however in some dogs it is a sign of parasites, malabsorption/maldigestion or underlying diseases associated with her gastrointestinal tract , pancreas or liver. If she is especially thin I would highly recommend having her checked.
Please let me know if you have any further questions.