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Black, Tarry Feces Due to Presence of Blood in Dogs

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Melena in Dogs


The term melena is used to describe stool that appears black and tarry, which occurs due to the presence of digested blood in the feces.


Melena typically occurs due to bleeding in the upper portion of the gastrointestinal tract. It has also been seen in dogs after they have ingested a sufficient amount of blood from the respiratory tract, for example from a nosebleed or coughing up and swallowing blood from the lungs. Melena is not a disease in itself but a symptom of some other underlying condition such as a gastrointestinal ulcer or blood clotting disorder. The dark color and tarry consistency of the feces occurs because of the digestion of blood as it passes through the intestinal tract.


Symptoms and Types


Other symptoms related to melena 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 respiratory tract, other symptoms might include:
    • Nose bleed
    • 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:
    • Nose bleed
    • Blood in urine
    • Bright red blood in the stool
    • Blood in the eyes
    • Vomiting, with or without blood
    • Abnormal bruising
    • Anemia
    • Pale mucous membranes
    • Weakness and exercise intolerance
    • Difficult or rapid breathing



Melena 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




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 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.  


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