When your dog has black poop you should not ignore it. A few causes of black stool in dogs include toxins a foreign body in the gastrointestinal tract pancreatitis kidney failure cancer and internal bleeding.
As you can see none of these sounds remotely appealing. In other words if your dog is pooping black you need to call your veterinarian right away.
However there is one exception.
That applies to dogs who are on raw food diets and whose poop is black.
Black poop isnot a result of your dog having something wrong with them but rather of eating a certain type of food.
Both of my dogs are on a raw food diet and eat different kinds of meat.
About once a week they will have a black poop.
They ate a lot of blood in the meat they consumed most recently.
Foods rich in iron tend to produce black poop and my dogs eat a blend of ox (cow) mince which makes their poop much darker.