Mine also has dark spots .. I don't think is is related to diet but related to the fact that some dog breeds ( include gsd's ) get black gums caused by melanin. Should check up with vet... Also raw diet makes dogs teeth pearly white.. If anything you should see improvement in the whiteness of your dogs teeth and less bad breath compared to kibble. If your dog is given a raw meaty bone daily, then you shouldn't have to worry too much about brushing. If you are like me and doing a freeze dried with the ground bone in it you might want to give your puppy a bully stick every day as this helps keep the teeth clean.