Dark Stool in Dogs

By Jane Meggitt

When you're picking up after your dog, it's important to be aware of the color and consistency of his stool. His output reveals what his innards are doing. If your pet starts producing dark stools, that indicates blood in his gastrointestinal tract. Make an appointment with your vet and bring your pooch's stool sample. Other fecal features, such as a tarry appearance, also can help your vet make a diagnosis.

Melena in Dogs

Technically known as melena, dark stools in dogs indicates that digested blood has passed through his intestinal tract. If you see fresh, red blood in your dog's feces, that may indicate hematochezia. Bleeding in your dog's stomach, or his small intestines, results in melena because the blood is digested. If the respiratory tract is the source of the bleeding, your pet might experience breathing problems or nose bleeds. Because melena can result from various diseases or causes, your vet must conduct a complete examination of your dog, along with blood, fecal and urine testing. She might also perform X-rays or ultrasounds on your pet.

Canine Gastroenteritis

Vomiting and diarrhea are the primary symptoms of gastroenteritis, and if the diarrhea is dark, this indicates bleeding in the gastrointestinal tract. This digestive tract inflammation has many causes. You can help your vet narrow them down by providing detailed information about your dog's dietary habits and whether he ate anything he shouldn't. In severe cases, your vet might administer intravenous fluids to replace those lost from vomiting and loose stools. Sometimes, gastroenteritis indicates underlying kidney or liver disease, pancreatitis or other serious conditions. Your vet likely will conduct various tests to determine the reason for the gastroenteritis.

Canine Ulcers

Ulcers in a dog's digestive tract can result from certain medications or from disease. Nonsteroidal anti-inflammatory drugs for pain can cause stomach ulcers in dogs. Along with melena, symptoms of canine ulcers include appetite loss, abdominal pain and vomiting blood. Diseases causing ulcers include kidney issues, Cushing's disease and inflammatory bowel disease. As with people, stressed-out dogs can develop ulcers.

Intestinal Cancer

Dark stools can indicate the presence of intestinal tumors. While any dog can develop intestinal cancer, it's more common in middle-aged, older male dogs, with German shepherds and collies particularly vulnerable. Besides dark stools, symptoms include weight and appetite loss, vomiting and diarrhea. Lymphoma is the most common type of intestinal cancer in canines. Unfortunately, the prognosis for most types of canine intestinal cancer is not good, with most dogs living one year or less after diagnosis.