Bleeding from a cat’s rear end usually comes from one of a handful of common causes: anal gland problems, constipation, parasites, colitis, or growths in the rectum. The color of the blood, your cat’s age, and any other symptoms like straining or scooting can help narrow down what’s going on. Most causes are treatable, but some need prompt veterinary attention.
What the Color of Blood Tells You
Bright red blood on your cat’s stool, around the anus, or on surfaces where your cat sits typically points to a problem in the lower digestive tract: the colon, rectum, or anal area. Because the blood hasn’t traveled far, it stays red and fresh-looking. You might see it streaked on the outside of stool, mixed into diarrhea, or as drops on the floor.
Dark, tarry, almost black stool is a different signal. That color means blood has been digested as it passed through the intestines, which points to bleeding higher up in the digestive system, like the stomach or small intestine. Hookworms, for example, feed on blood from the intestinal wall, and severe infections can turn a cat’s stool black and tarry. If you’re seeing dark stool rather than bright red blood, the underlying cause is likely different from what you’d expect with a surface-level anal issue.
Anal Gland Problems
Cats have two small scent glands just inside the anus, positioned roughly at the four o’clock and eight o’clock spots. These glands normally empty a small amount of fluid each time your cat has a bowel movement, but they can become clogged, infected, or abscessed. When that happens, the area around the anus swells, turns red, and becomes painful. You may notice your cat scooting its rear along the floor, licking or biting at the area obsessively, or showing discomfort when sitting down.
If an infected gland progresses to an abscess, the skin over it becomes thin and swollen. It can eventually rupture, releasing bloody or pus-filled discharge near the tail base. This looks alarming but is one of the more straightforward problems to treat. A vet can drain and flush the gland, and most cats recover quickly with a short course of treatment. Cats that get repeated anal gland infections may need the glands expressed regularly or, in rare cases, surgically removed.
Constipation and Straining
Hard, dry stool can scrape or tear the delicate lining of the rectum as it passes. If your cat is visibly straining in the litter box, producing small or unusually hard stools, or avoiding the box altogether, constipation is a likely culprit. The bleeding in this case is usually minor, with small amounts of bright red blood on the surface of the stool or around the anus.
Chronic straining carries a secondary risk: rectal prolapse, where part of the rectal lining pushes outward through the anus. This looks like a small, pink or red mass protruding from your cat’s rear. It can happen to cats of any age but is especially common in young cats with severe diarrhea or those who strain repeatedly. Prolapse requires veterinary treatment to reposition the tissue and address whatever caused the straining in the first place.
Parasites
Intestinal parasites are one of the most common causes of bloody stool in cats, with infection rates as high as 45% in some populations. Kittens are particularly vulnerable.
- Hookworms are tiny, thread-like worms (less than half an inch long) that attach to the intestinal wall and feed on blood. Mild infections cause diarrhea and weight loss. Severe cases cause anemia, and you’ll see dark, tarry stool from the digested blood.
- Coccidia are single-celled organisms that destroy the intestinal lining, especially in kittens. They cause mucousy, sometimes bloody diarrhea along with vomiting and poor appetite. Adult cats often carry coccidia without symptoms, but kittens can become seriously ill.
A standard fecal test at the vet can identify most common parasites. Treatment is usually straightforward with deworming medication, though kittens with severe infections may need supportive care for dehydration.
Colitis and Food-Related Inflammation
Colitis, or inflammation of the large intestine, is a frequent cause of blood-streaked diarrhea in cats. The inflamed lining of the colon bleeds easily, producing small amounts of bright red blood mixed into loose stool. Your cat may also strain during or after bowel movements, even when very little comes out.
The tricky part is that colitis has multiple triggers. Food allergies or intolerances are a major one, and they can look identical to inflammatory bowel disease (IBD) on examination and even under a microscope. The good news is that diet-responsive cases often improve significantly with a switch to a highly digestible or hypoallergenic food. Cats with chronic large bowel symptoms like bloody diarrhea that don’t respond to medication frequently turn out to have a dietary sensitivity rather than true IBD. Your vet may recommend a food trial with a novel protein or hydrolyzed diet lasting several weeks to see if symptoms resolve. Bacterial infections in the colon can also cause colitis, and these are treated differently.
Rectal Polyps and Growths
Polyps are small, typically benign growths that develop on the rectal lining. They cause straining, blood in the stool, and sometimes diarrhea. In some cases, a polyp may be visible as a small mass near the anus. Polyps are more common in older cats and are usually removed surgically. Malignant tumors in the rectum are less common but do occur, particularly in senior cats. Persistent bleeding that doesn’t respond to treatment for other causes warrants further investigation with imaging or biopsy.
Signs That Need Immediate Attention
A small streak of blood on an otherwise normal stool is worth monitoring and bringing up at your next vet visit. But certain signs mean your cat needs to be seen right away:
- Large amounts of blood (more than about a tablespoon)
- Pale gums, which suggest significant blood loss or anemia
- Lethargy, weakness, or feeling cold to the touch
- A swollen abdomen
- Rapid or labored breathing
- Persistent vomiting, especially if the vomit also contains blood
- Known exposure to toxins or recent trauma
What Happens at the Vet
A vet visit for rectal bleeding typically starts with a physical exam, including a check of the anal glands and a gentle rectal exam. A fecal sample is standard to screen for parasites and protozoal infections like giardia. Blood work helps assess whether your cat is anemic or has signs of infection or organ problems. If the cause isn’t obvious from these initial steps, abdominal ultrasound is often the next move. It’s more useful than endoscopy for determining whether the small intestine, large intestine, or both are involved, and it can reveal mass lesions that might need surgical removal.
Treatment depends entirely on the cause. Parasites are cleared with targeted medication. Anal gland issues are resolved with drainage and sometimes antibiotics. Dietary problems respond to food changes. Polyps or masses may require surgery. Most cats with rectal bleeding recover well once the underlying problem is identified and addressed.