Black, Tarry Feces Due to Presence of Blood in Dogs

PetMD Editorial
November 13, 2009
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The term melena is used to describe black, tarry stools in dogs, which is due to the presence of digested blood in the feces.

Melena in dogs typically occurs due to bleeding in the upper portion of the gastrointestinal tract. It has also been seen after they have ingested a sufficient amount of blood from the respiratory tract—for example, from a nosebleed or from coughing up and swallowing blood from the lungs.

Dog melena is not a disease in itself but a symptom of an underlying condition such as a gastrointestinal ulcer or blood clotting disorder. The dark color and tarry consistency of the feces occurs because the blood is digested as it passes through the intestinal tract.

Symptoms and Types of Melena in Dogs

Other symptoms related to melena in dogs depend on the bleeding’s underlying cause, severity and location.

  • In patients with gastrointestinal bleeding, other symptoms might include:

    • Vomiting, with or without blood

    • Lack of appetite

    • Weight loss

    • Weakness and exercise intolerance

    • Pale mucous membranes

    • Anemia

    • Difficult or rapid breathing

    • Abdominal pain

  • In patients with bleeding in the respiratory tract, other symptoms might include:

    • Nosebleed

    • Sneezing

    • Coughing up blood

    • Pale mucous membranes

    • Anemia

    • Weakness and exercise intolerance

    • Difficult or rapid breathing

  • In patients with abnormal blood clotting disorders, other symptoms might include:

    • Nosebleed

    • Blood in the urine

    • Bright red blood in the stool

    • Blood in the eyes

    • Vomiting, with or without blood

    • Abnormal bruising or spotting on the skin

    • Anemia

    • Pale mucous membranes

    • Weakness and exercise intolerance

    • Difficult or rapid breathing


Causes of Dog Melena

Melena in dogs can have many causes, including:

  • Ulcers in the gastrointestinal system

  • Tumors of the mouth, esophagus, stomach or small intestine

  • Gastrointestinal infections

  • Foreign body in the gastrointestinal system

  • Disorders involving inflammation of the intestinal tract

  • Kidney failure

  • Addison’s disease

  • Drug toxicity

  • Exposure to toxins

  • Parasites

  • Liver disease

  • Pancreatitis

  • Hormonal disorders

  • Infections, cancer or foreign bodies within the lungs or nose

  • Trauma

  • Disorders involving abnormal clotting of blood

  • Cancer



You will need to give a thorough history of your dog's health, onset of symptoms and possible incidents that might have led to this condition. The history you provide may give your veterinarian clues as to where the blood is originating from.

After taking a complete history, your pet’s veterinarian will conduct a complete physical examination. Standard laboratory tests for dogs with melena can include a complete blood count (CBC), biochemistry profile, fecal examination and urinalysis.

The results of these tests will reveal how serious your dog’s melena is and can possibly point to the potential underlying cause. Additional procedures and testing may also be necessary. These can include X-rays, ultrasound imaging, endoscopy, specialized blood tests, surgery and tissue biopsies, depending on the particulars of your dog’s case.  

what should your dog's poop look like?


The major goal of therapy is to address the underlying disease, which, if successful, should ultimately resolve the melena. Fluid therapy may be given to replace deficit fluids in the body, and in patients with severe blood loss and anemia, a blood transfusion may also be required.

Additional treatment will depend on a patient’s other symptoms and the underlying cause of the melena. For example, dogs with gastrointestinal ulcers may be treated with a change in diet and prescription pet medications to reduce the secretion of gastric acid, protect the lining of the gastrointestinal tract and limit vomiting (if necessary). Dogs who have ingested certain types of rodenticides will be treated with vitamin K.

Living and Management

The duration and type of treatment prescribed for your dog will depend on the underlying cause and the severity of the melena. Initially, frequent blood testing may be required to evaluate your dog for ongoing or worsening anemia, which may turn into more intermittent testing once your dog's health has stabilized.

Watch your dog for the worsening of any of his clinical signs during treatment, and talk to your veterinarian if you have any concerns.

Most patients will recover from melena as long as the underlying disease can be adequately addressed.