Blood in Your Cat's Stool: Causes, When to Worry, and What To Do

Discovering blood in your cat's litter box is understandably alarming. Whether it appears as bright red streaks alongside formed stool or dark, tarry-looking feces, blood in a cat's bowel movements signals that something is happening inside their digestive system — and the type of blood, the amount, and your cat's overall behavior together determine whether this warrants immediate emergency care or careful monitoring at home.

Understanding the Two Types of Blood in Cat Stool

Hematochezia (Bright Red Blood)

Bright red, fresh-looking blood in or around your cat's stool indicates bleeding in the lower digestive tract — the colon, rectum, or anus. Because the blood hasn't traveled far through the digestive system, it hasn't been digested and appears red. This type is generally considered less urgent than dark blood, though it still warrants attention.

Common causes of hematochezia in cats include:

• Colitis — inflammation of the large intestine, frequently triggered by stress (a new pet, visitor, move, or schedule change), a sudden diet switch, or an intestinal infection
• Constipation — straining repeatedly to defecate can rupture small blood vessels in the rectal lining
• Intestinal parasites — hookworms, Giardia, and Tritrichomonas foetus (a protozoal parasite common in young cats from multi-cat environments) all cause bloody stool with mucus
• Rectal polyps — benign growths in the lower bowel
• Anal gland disease — impacted or infected anal glands cause irritation and bleeding around the anus

Melena (Dark, Tarry Stool)

Melena appears as dark, black, tar-like, or coffee-ground-textured stool. It indicates bleeding higher in the digestive tract — the stomach or small intestine. The blood has been fully or partially digested during its journey through the GI tract, which is why it appears dark rather than red. Melena is generally a more serious finding than hematochezia and warrants prompt — often same-day — veterinary evaluation.

Causes of melena in cats include stomach or small intestinal ulcers, foreign body ingestion, intestinal lymphoma or other tumors, and systemic clotting disorders.

Stress Colitis

Cats are highly sensitive to environmental change, and acute stress colitis is one of the most common causes of bloody stool in otherwise healthy cats. A new family member, a new pet, a recent boarding stay, construction noise, or even a change in the daily routine can trigger inflammation of the colon. The stool is typically soft, more frequent than usual, and contains small amounts of bright red blood and mucus. Affected cats are usually still eating, grooming, and behaving normally otherwise.

When To Seek Emergency or Same-Day Veterinary Care

Contact your vet promptly or go to an emergency clinic if:

• The amount of blood is large rather than small streaks
• The stool appears dark, black, or tarry (melena)
• Blood is accompanied by vomiting, lethargy, appetite loss, or weight loss
• Your cat is straining repeatedly in the litter box and producing little or nothing — note carefully whether the straining is to defecate or to urinate. Male cats that cannot urinate have a life-threatening urethral blockage requiring emergency care within hours.
• Pale or white gums — suggests significant blood loss
• Known or suspected ingestion of a toxin, foreign object, or medication
• Symptoms persist for more than 24 hours or are clearly worsening
• Your cat has lost weight alongside recurring bloody stools

What To Do at Home

If your cat is passing a small amount of bright red blood alongside an otherwise normal stool, is acting completely normal, and has none of the emergency signs above, you may monitor at home for 12 to 24 hours:

1. Observe closely — is the blood increasing? Is your cat eating, drinking, and using the litter box normally?
2. Offer a bland diet temporarily — plain boiled chicken (no seasoning) can reduce GI inflammation while the gut settles.
3. Assess for recent stressors — did anything change in the home recently? New pet, visitor, move, or boarding?
4. Keep fresh water available at all times — hydration supports gut recovery.
5. Never give human medications — ibuprofen, acetaminophen, and aspirin are highly toxic to cats and can themselves cause GI bleeding.
6. Save a stool sample in a sealed bag if you can — your vet may want it for parasite testing.

Any case involving dark stool, large amounts of blood, or a cat that is unwell in any way requires same-day veterinary attention.

How Voyage Can Help

Blood in a cat's stool looks different and means something different depending on its color, consistency, and what else your cat is doing. Voyage's AI vet assistant helps you interpret what you're seeing and gives you a clear, personalized recommendation on whether this is a "monitor at home" situation or one that needs a vet today. Available 24/7 for $4.99/month — no appointment needed.

This article is for informational purposes only and is not a substitute for professional veterinary advice.