Bloody Stool (Hematochezia and Melena) in Cats

Key Takeaways

Blood in the feces is a common finding in many conditions which range in severity from mild to life-threatening.

• In most cases, bleeding is due to conditions of the gastrointestinal tract itself, such as injuries, tumors, infectious diseases, or inflammation

• Bleeding disorders can also cause bloody stool, and can be a life-threatening emergency

• Digested blood appears black and tarry in the stool and indicates bleeding from higher in the small intestine or stomach

• Bright red streaks, drops, or jelly-like clumps appear when the colon or rectum are the source of the bleeding

• Specific diagnosis requires blood work, stool analysis, and diagnostic imaging

• Specific treatment depends on the underlying condition but in many cases supportive care such as IV fluids is provided

A Closer Look: What is Bloody Stool in Cats?

Blood in the feces falls into two major categories: hematochezia and melena. These categories broadly refer to the appearance  of blood found in the feces, and indicate what location in the gastrointestinal tract the blood came from. 

Melena is black and tarry blood in the stool that results when bleeding occurs high in the digestive tract, such as in the esophagus, stomach, or small intestine. Blood mixes with intestinal contents, and becomes partially digested. 

Hematochezia refers to red, undigested blood in the stool that results from bleeding in the lower portions of the gastrointestinal tract, such as the colon, rectum, or anus. Both melena and hematochezia have many possible causes, ranging from mild to potentially life-threatening. On its own, blood in the feces is not an indication of the severity of the underlying problem.

Possible Causes

Bleeding in the gastrointestinal tract is either related to conditions within the digestive system itself, or a clotting disorder affecting the entire body. Conditions associated with blood in the feces include:

• Colitis • Hemorrhagic gastroenteritis • Inflammatory bowel disease • Gastrointestinal parasites

• Anticoagulant rodenticide toxicity • Tumors of the intestinal tract (intestinal cancer) • NSAID toxicosis

• Chronic kidney disease • Cholecalciferol (Vitamin D) toxicosis • Injuries • Reaction to certain medications

• Infectious diseases, including calicivirus, panleukopenia, feline leukemia, and feline immunodeficiency virus

Risk Factors

Blood in the feces is a nonspecific finding that indicates a range of underlying conditions. Some associated conditions are mild, with a good prognosis, while others may be life-threatening.  Many healthy cats occasionally pass feces with small drops or streaks of blood and no other symptoms. Minor, temporary bleeding from the colon or rectum commonly occurs along with straining, stress, or the passage of particularly dry or scratchy stool. Frequent or persistent passage of bloody stools is indicative of a variety of more serious underlying conditions and warrants veterinary attention.     Bleeding disorders, such as what occurs with anticoagulant rodenticide toxicosis, are an occasional cause of bloody stool and have the potential to be life-threatening. Cats with pale gums, extreme lethargy, and difficulty breathing require immediate veterinary attention.

Testing and Diagnosis

Diagnostic tests often include:

• Physical exam • Blood work, including tests for coagulopathies • Testing for bacterial, viral, or parasitic infections

• Diagnostic imaging such as X-rays or ultrasound • Endoscopy • Biopsies of the affected part of the digestive tract

Specific treatment depends on the diagnosis. Supportive care for patients with blood in the feces includes: 

• IV fluids • Blood transfusions • Nutritional therapy • Gastrointestinal protectant medications

Similar symptoms

Some medications cause dark feces, which resembles melena. These medications include bismuth subsalicylate, sucralfate, and activated charcoal. Many cats with hematochezia also have dyschezia (painful or difficult defecation). Distinguishing between dyschezia and painful defecation is particularly difficult in cats, as it is uncommon to observe them using the litter box.

Associated Symptoms

Symptoms commonly associated with blood in the feces include:

• Straining to defecate (tenesmus) • Painful defecation (dyschezia), including vocalizing during defecation

• Diarrhea • Constipation • Vomiting • Reduced appetite • Weight loss

Symptoms of a clotting disorder include: 

• Pale gums • Nosebleeds (epistaxis) • Coughing up blood • Bloody saliva • Rapid breathing (tachypnea)

• Small dark brown or red spots on the gums and skin • Blood in the urine • Extreme weakness and lethargy

• Difficulty breathing (dyspnea)

Note: symptoms of clotting disorder indicate serious, life-threatening disease, and require immediate veterinary attention.