Black Stool in Cats
- See your vet immediately if your cat has black, tarry stool, especially with vomiting, weakness, pale gums, collapse, or poor appetite.
- Black stool often means digested blood, called melena, coming from the stomach or small intestine rather than the lower colon.
- Common causes include stomach or intestinal ulcers, toxins or human medications, parasites, inflammatory disease, kidney disease, liver disease, and cancer.
- Diagnosis may include a physical exam, bloodwork, fecal testing, imaging, and sometimes ultrasound or endoscopy to find the bleeding source.
- Treatment depends on the cause and can range from outpatient medications and diet changes to hospitalization, transfusion support, or surgery.
Overview
See your vet immediately. Black stool in cats is often called melena. It usually means blood has been digested as it moved through the stomach or small intestine, which turns the stool dark, sticky, and tar-like. This is different from small streaks of bright red blood, which more often come from the colon, rectum, or anus.
Melena is a symptom, not a diagnosis. Some cats still act fairly normal at first, while others show vomiting, weakness, hiding, poor appetite, weight loss, or pale gums. Because blood loss can become serious quickly, even one episode of truly black, tarry stool deserves prompt veterinary attention.
In some cases, stool can look dark for reasons other than bleeding. Iron supplements, activated charcoal, or bismuth-containing products can darken stool, although bismuth subsalicylate products are not considered safe for cats unless your vet specifically directs their use. Swallowed blood from the mouth or nose can also make stool look black.
The main concern is that melena may point to gastrointestinal bleeding from ulcers, inflammation, parasites, clotting problems, organ disease, or tumors. The sooner your vet identifies the source, the better the chance of stabilizing your cat before anemia, dehydration, or shock develop.
Common Causes
One of the most common medical explanations for black stool is bleeding from the upper digestive tract. Stomach or intestinal ulcers can do this, and ulcers may develop secondary to kidney disease, severe inflammation, foreign material, stress on the body, or certain toxins and medications. Human pain relievers such as ibuprofen and naproxen are especially dangerous for cats and can damage the gastrointestinal tract while also causing other life-threatening problems.
Parasites are another possible cause, especially in kittens, outdoor cats, or cats with inconsistent preventive care. Hookworms can cause blood loss and anemia, and some cats with parasite burdens pass dark, tarry stool. Chronic intestinal inflammation, food-responsive enteropathy, and some infections can also irritate the gut enough to cause bleeding.
Systemic disease matters too. Kidney disease may contribute to ulcer formation, while liver disease and clotting disorders can make bleeding more likely. In older cats, intestinal tumors or cancers elsewhere in the body can lead to gastrointestinal bleeding. VCA notes that bleeding from tumors in the small intestine may make stool look blackish.
Less commonly, a cat may pass black stool after swallowing blood from dental disease, oral injury, or a nosebleed. That is why your vet will look beyond the litter box and consider the whole cat, including medications, toxin exposure, appetite, vomiting, weight changes, and gum color.
When to See Your Vet
See your vet immediately if your cat's stool is thick, black, and tarry. Merck lists thick black stools among signs that need immediate veterinary attention. This is even more urgent if your cat is vomiting, seems weak, is breathing faster than normal, has pale or white gums, refuses food, or collapses. Those signs can point to significant blood loss, anemia, or shock.
You should also seek same-day care if the black stool happens more than once, if your cat may have gotten into human medication, or if there is a history of kidney disease, liver disease, cancer, or recent surgery. Kittens, senior cats, and cats with chronic illness have less reserve and can worsen faster.
If you suspect toxin exposure, contact your vet right away. The ASPCA Animal Poison Control Center is available 24/7 at (888) 426-4435, and they recommend calling immediately if you think a pet ingested something toxic. Bring any medication bottles, chewed packaging, vomit photos, or stool photos with you if possible.
Do not try to treat black stool at home with over-the-counter human stomach or diarrhea products unless your vet tells you to. Some products can darken stool and make the situation harder to interpret, and some are not safe for cats.
How Your Vet Diagnoses This
Your vet will start with a history and physical exam. They will ask what the stool looked like, when it started, whether your cat has vomited, what medications or supplements your cat has had, and whether there could have been toxin exposure. Gum color, heart rate, hydration, abdominal pain, body condition, and temperature all help guide urgency.
Initial testing often includes bloodwork and a fecal evaluation. A complete blood count can look for anemia or infection, while chemistry testing can screen for kidney disease, liver disease, protein loss, and electrolyte changes. A fecal test may help identify parasites, and your vet may recommend repeat testing if the first sample is negative but suspicion remains high.
Imaging is often the next step if bleeding is ongoing or the cause is not obvious. X-rays can help look for foreign material, masses, or severe intestinal changes. Abdominal ultrasound can evaluate the stomach, intestines, liver, pancreas, lymph nodes, and other organs in more detail. In selected cases, endoscopy or surgery may be needed to directly inspect the gastrointestinal tract and collect biopsies.
Diagnosis is really about finding the source of bleeding and understanding how sick the cat is overall. That is why two cats with the same black stool can need very different workups. One may need only outpatient testing and medication, while another may need stabilization, imaging, transfusion support, and referral-level care.
Treatment Options
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Conservative Care
- Office or urgent-care exam
- Basic CBC/chemistry or packed cell volume check
- Fecal testing and parasite-directed treatment if indicated
- Outpatient anti-nausea and gastrointestinal support medications
- Diet trial or prescription gastrointestinal diet
- Short-interval recheck if stool stays black or appetite drops
Standard Care
- Comprehensive exam and history review
- CBC, chemistry panel, and additional lab testing as needed
- Fecal testing and parasite treatment if needed
- Abdominal x-rays
- Subcutaneous or IV fluids depending on status
- Prescription medications and therapeutic diet
- Recheck exam and repeat bloodwork if anemia or bleeding is a concern
Advanced Care
- Emergency stabilization and hospitalization
- Serial blood counts and advanced lab monitoring
- Abdominal ultrasound and/or endoscopy
- Blood typing and transfusion support if needed
- Surgery for foreign body, perforation, or biopsy collection
- Specialty referral for internal medicine, oncology, or critical care
Cost estimates as of 2026. Actual costs vary by location, clinic, and individual case.
Home Care & Monitoring
Home care should only happen after your vet has advised that your cat is stable enough to be managed outside the hospital. Give medications exactly as directed, feed only the recommended diet, and make sure fresh water is always available. If your cat is hiding, set up a quiet recovery space with easy access to the litter box, food, and water.
Monitor the stool closely for color, consistency, and frequency. True melena is usually black and tarry, not just dark brown. Taking a photo can help your vet compare changes over time. Also watch for vomiting, drooling, lip smacking, belly pain, reduced appetite, weight loss, or lower energy.
Check your cat's gums once or twice daily if your vet has shown you how. Pale gums, weakness, fast breathing, or collapse are red flags. If your cat stops eating, vomits repeatedly, or the stool remains black despite treatment, contact your vet promptly. Recheck bloodwork may be important even if the stool looks better.
Do not give human medications, antacids, pain relievers, or diarrhea remedies unless your vet specifically approves them. Keep all medications secured, and scoop the litter box at least daily so you can spot changes early.
Questions to Ask Your Vet
Bring these questions to your vet appointment to get the most out of your visit.
- Does this look like true melena or could something else be making the stool dark? This helps separate digested blood from dark stool caused by diet, supplements, charcoal, or swallowed blood.
- How urgent is my cat's condition based on gum color, hydration, and blood loss risk? It clarifies whether outpatient care is reasonable or if hospitalization is safer.
- What are the most likely causes in my cat's case? The answer guides next steps and helps pet parents understand whether ulcers, parasites, toxins, organ disease, or cancer are higher on the list.
- Which tests are most useful today, and which ones can wait if we need a staged plan? This supports Spectrum of Care decision-making and helps match the workup to the cat's needs and the family's budget.
- Are there any medications or toxins that could have caused this? Cats are very sensitive to many human medications, and identifying an exposure can change treatment quickly.
- What signs at home mean I should come back immediately? Clear return precautions help pet parents act fast if bleeding worsens or anemia develops.
- What diet and medications should I use at home, and for how long? This reduces confusion and improves the chance that treatment is followed correctly.
- Will my cat need repeat bloodwork or imaging after starting treatment? Follow-up testing is often needed to confirm that bleeding has stopped and anemia is improving.
FAQ
Is black stool in cats always an emergency?
It should be treated as urgent because black, tarry stool often means digested blood from the stomach or small intestine. Some cats look stable at first, but blood loss can become serious quickly. See your vet immediately, especially if your cat is weak, vomiting, pale, or not eating.
What is melena in cats?
Melena is the term for black, tarry stool caused by digested blood passing through the gastrointestinal tract. It is a symptom rather than a disease, so your vet still needs to find the underlying cause.
Can food make my cat's stool look black?
Sometimes stool can look darker after certain foods, iron, or activated charcoal, but true melena usually looks black and sticky or tar-like. Because it can be hard to tell at home, it is safest to have your vet evaluate it.
Can I give Pepto-Bismol or another over-the-counter remedy?
Do not give over-the-counter human medications unless your vet tells you to. Bismuth-containing products can darken stool and are not considered safe for cats without veterinary direction.
What tests will my cat need?
Many cats need a physical exam, bloodwork, and a fecal test first. Depending on the findings, your vet may also recommend x-rays, ultrasound, endoscopy, or other testing to locate the source of bleeding.
Can parasites cause black stool in cats?
Yes. Hookworms and some other intestinal parasites can cause blood loss, anemia, and dark or tarry stool, especially in kittens or cats with outdoor exposure.
How is black stool treated in cats?
Treatment depends on the cause. Options may include parasite treatment, stomach-protective medication, anti-nausea medication, fluids, diet changes, hospitalization, transfusion support, or surgery in severe cases.
How much does it cost to treat black stool in cats?
Costs vary widely based on severity and the tests needed. A basic outpatient visit may fall around $150 to $450, a more complete standard workup often ranges from $450 to $1,200, and advanced emergency or specialty care can reach $1,200 to $4,000 or more.