Dogs having bloody diarrhea should be taken to a veterinarian as soon as possible, especially if diarrhea contains a large amount of blood (e.g. more than a few drops or small streaks). Many disorders can cause bloody diarrhea, some more serious than others, and some life-threatening without treatment. However, regardless of the cause, significant blood loss in the stool can result in anemia—a low red blood cell count that can cause poor oxygen delivery to the body. It is important to address bloody stool as soon as possible to determine the underlying cause and prevent or treat serious complications.