Blood In Cat Stool (Melena) – Dark, Tarry Stools

Causes           Symptoms         Diagnosis           Treatment

Melena at a glance

  • Melana is the medical term for dark, tarry stools, which are caused by the presence of digested blood.
  • There are a number of causes of melena including ulcers, ingested foreign body, swallowed blood, tumours, trauma, infection, and poisoning.
  • Aside from black and tarry stools, symptoms can vary depending on the underlying cause.
  • Treatment is aimed at treating the cause and supportive care such as fluids where necessary and in severe cases, a blood transfusion.


melena in cats

There are two types of blood in the stool, melena and hematochezia.

  • Melena refers to blood in the stool which is black and tarry, this type of blood in the stool originates in the upper gastrointestinal tract.
  • Hematochezia  is the presence of bright red blood on or throughout the feces which originates in the lower gastrointestinal tract.

This article looks at what causes melena in cats. For information on hematochezia, read here.

The dark colour of melena is due to digested blood in the feces. This bleeding may originate from the pharynx, lungs (where the blood is coughed up and then swallowed), esophagus, stomach or upper small intestine. The colour and tarry texture is due to the breakdown of hemoglobin in the blood by bacteria in the stomach.

A large amount of blood is required to cause melena, therefore it should be treated as an emergency as there are a number of potentially serious causes of this condition. Seek immediate veterinary attention.


Melena isn’t a disease in itself, it is a symptom of an underlying disorder. There are many possible causes of melena in cats, including:

  • Gastrointestinal ulcers which could be due to stomach acid or by ingesting poison, chemical burns, certain medications such as anticoagulant drugs, aspirin, and ibuprofen.
  • A foreign body which causes damage anywhere along the upper intestinal tract.
  • Ingestion of blood by nosebleed, bleeding in the lungs, dental bleeding.
  • Blood clotting disorders such as disseminated intravascular coagulation, which is caused by multiple factors such as parasites, infection, inflammatory conditions, liver disease, snake bite, shock, pancreatitis and inflammatory conditions.
  • Aspirin poisoning can lead to internal bleeding.
  • Vitamin D toxicity which causes hypercalcemia.
  • Cancer anywhere along the upper gastrointestinal tract.
  • Trauma.
  • Infection.


Obviously, the most obvious symptom is black, tarry feces.  Other symptoms will depend on the underlying cause, common signs to look out for include:

  • Vomiting (which may or may not contain blood)
  • Abdominal pain
  • Loss of appetite (anorexia)
  • Difficulty breathing
  • Weight loss

Symptoms relating to specific conditions may include:

Anemia symptoms:

  • Lethargy
  • Weakness
  • Pale gums
  • Difficulty breathing

Blood clotting disorders symptoms:

  • Nosebleeds
  • Bruising under the skin
  • Blood in urine
  • Kidney failure
  • Liver failure
  • Heart failure

Aspirin toxicity:

  • Rapid breathing
  • Increased urination
  • Nervous system disturbances (excitability, loss of balance, seizures)
  • Jaundice
  • Fever

Vitamin D toxicity:

  • Weakness
  • Fatigue
  • Vomiting
  • Increased thirst
  • Increased urination
  • Muscle tremors
  • Seizures


Your veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. This will include questions about other symptoms you may have noticed, any medications, supplements or poisons your cat may have ingested. He will perform routine tests such as biochemical profile, complete blood count, and urinalysis to determine the overall health of your cat and look for any abnormalities in the blood, serum and urine which may narrow down the possible cause.

  • Complete blood count may reveal anemia (low red blood cell count), thrombocytopenia (low platelets), increased white blood cells.
  • Biochemical profile may reveal elevated liver enzymes, hyperbilirubinemia (high bilirubin levels in the serum), elevated BUN and creatinine levels.
  • Urinalysis may reveal blood in the urine.

Additional tests depending on your veterinarian’s index of suspicion may include:

  • Specialist blood and serum tests such as blood clotting tests, coagulation profile, blood gas test.
  • Blood smear examination to look for abnormalities in the red blood cells.
  • Fecal examination.
  • Upper gastrointestinal barium series to evaluate the upper gastrointestinal tract. Barium is a white powder which is not transparent to x-rays. The cat eats a barium meal which coats the GI structures, an x-ray will highlight tumours, ulcers and damage.
  • Endoscopy – A flexible tube with a camera at the end is inserted into the esophagus and into the stomach to look for tumours, blockages, ulcers, a biopsy may be taken during the procedure.
  • Xrays and/or ultrasound to look for tumours, blockages, foreign bodies and evaluate the kidneys and liver.
  • Echocardiogram (ECG) to examine the heart.


Obviously, the main goal of treatment is to address the underlying condition, once this has been determined and treated, the melena should improve. Often a sick cat will need supportive care such as IV fluids to treat dehydration and help the body flush out toxins, antiemetic medications to control vomiting, if anemia is severe, a blood transfusion may be required and a bland diet such as boiled chicken and rice which is easy for your cat to digest.

  • In the case of poisoning/ingestion of medications, induce vomiting, stomach pumping to remove the toxins from the system followed by activated charcoal.
  • Medications to protect the stomach lining such as ranitidine, cimetidine or famotidine if ibuprofen poisoning has occurred or the cat has ulcers.
  • Antacids to treat stomach ulcers.
  • Surgery to remove tumours or treat gastrointestinal ulcers, remove blockages and repair damage caused by trauma.
  • Calcitonin to help bring down calcium levels.
  • Supportive care such as intravenous fluids to treat dehydration and correct electrolyte balances as well as nutritional support.

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