Tar colored diarrhea Atlas of swine pathology pig333, pig to pork community Why Is My Stool Black? Symptoms, Causes & What To Do Next What poop color says about your health Baptist Health Jacksonville, FL Stool Poop Color What it may mean Brown: In GrepMed Dark stool vs black stool the difference can be serious. Dark brown stool is often food or iron related. Black, tarry stool may indicate internal bleeding and needs urgent medical attention. Foods That Cause Dark Stools and When to Be Concerned GoodRx