Black, tarry stool in cats is called melena, and it signals digested blood somewhere in the digestive tract. This is not something you can safely treat at home. A cat passing black stool needs a veterinary exam to find and address the source of bleeding, which could range from a treatable parasite infection to a serious ulcer or organ disease.
What Makes a Cat’s Stool Turn Black
When blood enters the upper digestive tract (the stomach or small intestine), it gets broken down by stomach acid and digestive enzymes as it moves through. By the time it reaches the litter box, the blood has oxidized into a dark, tar-like substance. The key factor is how long the blood stays in the digestive system, not necessarily where the bleeding started. Even a lower intestinal bleed can produce black stool if the blood moves slowly enough through the colon.
Normal cat stool is brown and firm. Black, sticky, tar-like stool looks and feels distinctly different from simply dark-colored poop. If you’re unsure whether what you’re seeing is truly melena, note the texture: melena has a characteristic glossy, almost gummy quality.
One Important Exception: Harmless Causes
Before assuming the worst, consider whether your cat has recently ingested anything that could darken stool without actual bleeding. Bismuth compounds (the active ingredient in some human stomach medications that a well-meaning owner might give) can turn stool grey-black or green-black. Iron supplements do the same. If your cat recently ate a high-iron food, liver-heavy diet, or got into a medication, that could explain the color. But if you can’t identify a clear harmless cause, treat it as a potential bleed.
Common Causes of Black Stool in Cats
The underlying causes span a wide range of severity:
- Intestinal parasites. Hookworms, Giardia, and coccidia can all damage the intestinal lining enough to cause bleeding. This is one of the more common and treatable causes, especially in kittens or outdoor cats.
- Gastrointestinal ulcers. Ulcers in the stomach or upper intestine are a frequent source of melena. These can develop on their own or as a complication of kidney disease, which causes toxin buildup that erodes the gut lining.
- Medication reactions. NSAIDs and corticosteroids are well-known culprits. In the U.S., only two NSAIDs are approved for cats, both for very short-term use only. Meloxicam is approved as a single injection, and robenacoxib for a maximum of three days. Repeated doses of meloxicam in cats can cause kidney failure and death. If your cat got into ibuprofen, aspirin, or any human pain reliever, this is an emergency.
- Swallowed foreign objects. Bones, string, or sharp objects can physically damage the digestive tract as they pass through.
- Tumors. Growths in the stomach or intestine can ulcerate and bleed. These tend to cause more prolonged symptoms along with weight loss.
Signs That It’s an Emergency
Black stool on its own warrants a vet visit, but certain accompanying signs mean your cat is losing blood fast enough to be in danger. Check your cat’s gums by gently lifting the upper lip. Healthy gums are light rosy pink. If they look pale pink, white, or greyish, your cat may be anemic or going into shock from blood loss.
Other urgent signs include lethargy or collapse, vomiting (especially if it contains dark or coffee-ground-like material), rapid breathing, weakness, or refusal to eat. A cat showing any of these alongside black stool needs same-day or emergency veterinary care.
How Vets Diagnose the Cause
Your vet will likely start with a physical exam and blood work to check for anemia and organ function, particularly kidney and liver values. A fecal test can detect parasites, and a fecal occult blood test can confirm whether blood is present in the stool if there’s any doubt. Depending on findings, imaging like X-rays or ultrasound can reveal foreign bodies, masses, or thickened intestinal walls. In some cases, endoscopy (a small camera passed into the stomach) is needed to directly visualize and biopsy an ulcer or growth.
How Black Stool Is Treated
Treatment targets the underlying cause, not the black stool itself. There’s no home remedy that safely addresses internal bleeding in a cat.
For Ulcers
Stomach and intestinal ulcers are typically treated with acid-suppressing medications. Proton pump inhibitors are considered the standard of care for cats with ulcers, and they’re more effective than older acid-blocking drugs. Your vet will generally prescribe these twice daily to adequately control stomach acid. If your cat has been on this type of medication for four weeks or longer, it needs to be tapered gradually rather than stopped abruptly, because sudden withdrawal can trigger a rebound surge in acid production. The dose is typically reduced by half each week.
A protective coating agent called sucralfate is sometimes used alongside other treatments, though evidence for its effectiveness is limited. If prescribed, a liquid form works better than tablets, which may not fully dissolve in a cat’s stomach.
Treatment timelines vary. Cats with ulcers from infections or medication reactions often recover within two to four weeks of appropriate treatment. Ulcers linked to tumors require longer management, though even these cats can be kept comfortable for extended periods with the right approach.
For Parasites
If parasites are the cause, deworming medication resolves the problem relatively quickly. Your vet will choose the appropriate antiparasitic based on which organism is identified in the fecal test. Follow-up fecal checks confirm the infection has cleared.
For Medication-Induced Bleeding
If a drug caused the bleeding, the first step is stopping that medication immediately. Cats who ingested human NSAIDs like ibuprofen or naproxen may need hospitalized supportive care including fluid therapy and gut-protective medications. The prognosis depends on how much was ingested and how quickly treatment begins.
For Foreign Bodies
Sharp or obstructing foreign objects sometimes require surgical removal. Smaller items that haven’t caused a perforation may pass on their own with monitoring.
Feeding During Recovery
The old advice of boiling chicken and rice for a sick cat is outdated. That combination is deficient in more than ten essential nutrients for cats and isn’t appropriate for recovery. Instead, veterinary therapeutic gastrointestinal diets are specifically formulated for cats with digestive issues. These foods are highly digestible, meaning your cat absorbs more nutrients from less food, which reduces the workload on a healing gut.
Your vet may recommend a diet that’s low in fat, high in certain fibers, or made with hydrolyzed proteins depending on the underlying cause. If inflammatory bowel disease or a food allergy is suspected, a hypoallergenic diet with novel protein sources may be part of longer-term management. During recovery, feeding smaller meals more frequently (four or more times daily instead of two) helps keep digestion gentle and steady.
What Recovery Looks Like
Cats with non-cancerous causes of black stool generally have an excellent prognosis once the underlying problem is identified and treated. You should see stool color return to normal brown within a few days of bleeding stopping, though your vet may want follow-up blood work to confirm your cat isn’t still anemic. Cats with tumor-related bleeding face a more variable outlook, but appropriate treatment can maintain quality of life for prolonged periods even in those cases.
The most important thing you can do right now is get your cat examined. Black stool means blood has been in the digestive system long enough to be fully digested, and the cause needs to be identified before it can be properly treated.