Blood in Cat Stool: Causes & When to Worry
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Blood in a cat's stool is common and has many causes — from a passing bout of colitis or a food change to parasites, infections or inflammatory bowel disease. Bright red blood usually comes from the lower bowel and is often less alarming; black, tarry stool suggests digested blood from higher up and is more concerning. A single small streak in an otherwise well cat can be watched briefly, but repeated blood, or blood with vomiting, lethargy or a poor appetite, warrants a vet visit.
When to call the vet promptly
Contact your vet right away — don't wait — if blood in the stool comes with any of these:
- Black, tarry, or coffee-ground-like stool (digested blood)
- A large amount of blood, or blood at every bowel movement
- Vomiting, especially repeated or with blood
- Lethargy, weakness, pale gums, or hiding
- Not eating, a painful belly, or a bloated abdomen
- Straining with little produced, or a kitten or senior cat affected
These combinations can point to serious problems — from significant blood loss to obstruction or systemic illness — and shouldn't be watched at home.
What the color and type tell you
The appearance of the blood is a useful clue about where it's coming from:
| What you see | Likely origin |
|---|---|
| Bright red blood (hematochezia) | Lower bowel, rectum or anus — often colitis, parasites, or straining |
| Dark, black, tarry stool (melena) | Digested blood from the stomach or upper intestine — more concerning |
| Blood with mucus and soft stool | Colitis (inflammation of the large intestine) |
| Blood streaked on formed stool | Often from the rectum or anus, sometimes constipation or straining |
Snapping a clear photo of the stool (and noting whether it's firm, loose or watery) gives your vet far more to work with than a description alone.
Common causes
Blood in the stool is a symptom shared by many conditions, including:
- Dietary upset — a sudden food change, dietary indiscretion, or food intolerance
- Intestinal parasites — worms and protozoa like Giardia, especially in kittens
- Colitis — inflammation of the large intestine, often with mucus and straining
- Infections — bacterial or viral, including panleukopenia in unvaccinated kittens
- Inflammatory bowel disease (IBD) and food allergies in ongoing cases
- Constipation and straining, anal-gland problems, or foreign objects
- Less commonly, clotting disorders, polyps or tumors, more often in older cats
Kittens and senior cats are more vulnerable, so blood in their stool deserves a lower threshold for calling the vet.
What to watch and note at home
If your cat is otherwise bright, eating normally, and you see a single small streak of bright red blood, it's reasonable to monitor closely for a day while you contact your vet for advice. Keep track of:
- How often it's happening and whether it's getting worse
- Stool consistency — firm, soft, loose or watery
- Appetite, energy, and any vomiting
- Recent changes — new food, treats, medications, or stress
Practical take: Bring a fresh stool sample to your appointment. A parasite check on a recent sample is one of the fastest, cheapest ways to rule in or out a very common cause.
How it's diagnosed and treated
Your vet starts with a history and physical exam, then chooses tests based on how sick your cat is:
- Fecal testing for parasites and, sometimes, bacterial causes
- Bloodwork to assess blood loss, organ function and inflammation
- Imaging (X-ray or ultrasound) for obstruction, masses or thickened bowel
- Diet trials, and occasionally biopsy for suspected IBD or food allergy
Treatment follows the cause: deworming for parasites, a bland or prescription diet for dietary and inflammatory issues, fluids for dehydration, and specific medication for infection or IBD. Many mild cases resolve quickly once the trigger is addressed.
Why tracking bowel changes helps
Digestive problems in cats often come and go, and a single episode looks very different from a recurring pattern. Logging each time you see blood, the stool's consistency, and any diet or routine changes turns scattered observations into a timeline your vet can actually use — helpful for spotting food triggers and for catching chronic conditions like IBD early. Noting a new food the week before a flare, for instance, can point straight at the cause.
Turn scattered symptoms into a clear picture
Tavi lets you log stool changes, diet, and other symptoms with dates and photos, then see the pattern over time — so you can tell your vet exactly what changed and when. Free for your first pet.
Frequently asked questions
Is a little blood in cat stool an emergency?
A single small streak of bright red blood in a cat that is otherwise well, eating and active can often be monitored for a day while you contact your vet for advice. However, black tarry stool, large amounts of blood, or blood with vomiting, lethargy or poor appetite needs prompt veterinary care.
What does black, tarry stool mean in cats?
Black, tarry or coffee-ground-colored stool (melena) usually means digested blood from the stomach or upper intestine, which is more concerning than fresh red blood from the lower bowel. It can indicate ulcers, bleeding higher in the digestive tract, or other serious problems, so it warrants a prompt vet visit.
Can worms cause blood in a cat's stool?
Yes. Intestinal parasites, including hookworms, whipworms and protozoa like Giardia, are a common cause of bloody or mucousy stool, particularly in kittens. A fecal test on a fresh sample is a quick way to check, and most parasites are treated effectively with deworming medication.
Why does my cat have blood and mucus in soft stool?
Blood mixed with mucus and soft stool is a classic sign of colitis, or inflammation of the large intestine. It can be triggered by diet changes, parasites, infections, stress or inflammatory bowel disease. If it persists more than a day or two, or your cat seems unwell, have your vet investigate the underlying cause.
Should I bring a stool sample to the vet?
Yes, a fresh stool sample is very helpful. It lets your vet run a fecal test for parasites and assess the stool directly, which is one of the fastest and least expensive ways to identify a common cause. A clear photo of the stool is also useful if you can't collect a sample.
Tavi's guides are informational and not a substitute for professional veterinary advice, diagnosis or treatment. When in doubt, call your veterinarian. Sources: Cornell University Feline Health Center; VCA Animal Hospitals; American Association of Feline Practitioners (AAFP); Merck Veterinary Manual; International Cat Care