A cat bleeding from the anus can have causes ranging from mild constipation to serious internal disease. The color of the blood is your first clue: bright red blood typically comes from the lower intestine, rectum, or anus itself, while dark, tarry stool signals bleeding higher up in the digestive tract where blood has been partially digested. Either type warrants veterinary attention, but the combination of bleeding with lethargy, pale gums, or loss of appetite points to an emergency.
What the Color of Blood Tells You
Bright red blood on the surface of stool or around your cat’s rear end is called hematochezia. It usually means the source of bleeding is in the large intestine, rectum, or anal area. Because the blood hasn’t traveled far, it stays red. This is the most common presentation cat owners notice.
Dark, black, or tarry-looking stool is called melena. It means blood entered the digestive tract higher up, in the stomach or small intestine, and was partially broken down during digestion. Melena can be easy to miss because it doesn’t look like obvious bleeding. It often has a distinctly foul smell compared to normal stool. However, the color isn’t a perfect map of location. Very heavy upper GI bleeding can move through the system so fast it still appears bright red, and slow lower GI bleeding can darken if stool sits in the colon long enough.
Constipation and Straining
One of the simplest explanations is mechanical trauma from passing hard, dry stool. When a cat strains repeatedly, the delicate lining of the rectum and anus can tear, leaving streaks of bright red blood on the stool or around the litter box. Cats prone to dehydration or those on low-moisture diets are especially vulnerable.
In more severe cases, chronic constipation can progress to megacolon, a condition where the colon becomes stretched and loses its ability to push stool forward. The retained stool mass can press against the intestinal wall hard enough to damage tissue. One documented case in a cat showed that colonic obstruction led to spotty oozing blood visible on the intestinal surface during examination. If your cat is producing small, hard stools infrequently, or straining in the litter box without producing anything, constipation is a likely contributor.
Anal Gland Problems
Cats have two small scent glands just inside the anus that normally express small amounts of fluid during bowel movements. When these glands become impacted, their contents thicken and the sac swells, creating discomfort. An impacted anal gland can progress to infection and then abscess formation. A ruptured anal gland abscess releases pus and blood from a visible swelling right next to the anus.
Signs to watch for include your cat scooting along the floor, excessively licking the area under the tail, or visible redness and swelling on one or both sides of the anus. You may notice bloody or foul-smelling discharge on furniture or bedding. Anal gland issues are more common in dogs, but they do occur in cats and are usually treatable with drainage and medication.
Intestinal Parasites
Several parasites can cause bleeding in a cat’s digestive tract. Hookworms are small bloodsucking worms, only 5 to 15 millimeters long, that latch onto the lining of the small intestine and feed directly on blood. A heavy hookworm infection can cause hemorrhagic diarrhea and even anemia in severe cases. Light infections may cause no visible symptoms at all.
Coccidia, a single-celled parasite, damages the intestinal lining by invading and destroying the cells that line the gut wall. This is especially common in kittens and cats with weakened immune systems. Both hookworms and coccidia are diagnosed through a simple fecal test at the vet, and treatment is straightforward once the parasite is identified.
Colitis and Inflammatory Bowel Disease
Colitis, or inflammation of the large intestine, is one of the more common causes of bloody stool in cats. When the colon is inflamed, the protective lining breaks down, allowing blood and mucus to mix into the stool. A cat with colitis typically produces frequent, small amounts of stool, often with visible straining. The blood is usually bright red and may be accompanied by a mucus coating.
Inflammatory bowel disease (IBD) is a chronic condition where the immune system sends waves of inflammatory cells into the walls of the stomach and intestines. Over time, this infiltration disrupts the normal architecture of the gut lining, causing villous atrophy (flattening of the tiny finger-like projections that absorb nutrients) and scarring. When the colon is involved, the result is large bowel diarrhea with blood, mucus, and straining. IBD tends to cause recurring episodes and is managed long-term with dietary changes and anti-inflammatory treatment.
Tumors and Polyps
Growths in the intestine or rectum can bleed as they expand or ulcerate. Benign growths like polyps and adenomas are possible, and so are malignant tumors including adenocarcinoma, lymphoma, and mast cell tumors. Intestinal tumors in cats often cause weight loss, decreased appetite, vomiting, or diarrhea alongside the bleeding. Fresh or digested blood may appear in the stool depending on where the tumor is located.
Rectal polyps sometimes cause intermittent bright red bleeding that comes and goes over weeks or months. Malignant tumors tend to produce more progressive symptoms. Intestinal tumors are more common in older cats, and diagnosis typically requires imaging and biopsy. Early detection makes a significant difference in treatment options.
Rodenticide Poisoning
If your cat has any possible access to rat or mouse poison, this is a cause that requires immediate emergency care. Anticoagulant rodenticides work by blocking vitamin K recycling in the liver, which disables the clotting factors that stop bleeding. Without functional clotting, a cat can bleed internally and externally from multiple sites.
In a study of seven cats with suspected anticoagulant rodenticide poisoning, bleeding appeared in multiple forms: bloody stool, dark tarry stool, bruising, blood-filled chest cavities, and bleeding from the ears. Clinical signs of hemorrhage can appear two to five days after exposure. Cats don’t need to eat the poison directly; they can be poisoned by eating a mouse or rat that recently consumed bait. If you see unexplained bleeding from multiple areas, or bleeding combined with difficulty breathing, this is a veterinary emergency.
Swallowed Foreign Objects
Cats are notorious for swallowing string, thread, ribbon, and tinsel. These linear foreign bodies can anchor at one point (often under the tongue or at the stomach exit) while the rest of the string gets pulled deeper into the intestines by normal gut movement. The intestine bunches up along the string like fabric on a drawstring, and the taut material can saw through the intestinal wall, causing perforation and internal bleeding.
Vomiting is the most common sign, occurring in 96% of cats with foreign bodies in one large study. Anorexia and lethargy are also typical. Diarrhea, including bloody diarrhea, is less common but does occur. Linear foreign bodies tend to cause more diffuse intestinal damage than a single swallowed object, leading to longer surgeries, higher infection rates, and more intensive recovery. If you see string hanging from your cat’s mouth or anus, do not pull it. Pulling can worsen internal lacerations.
Signs That Require Urgent Care
A single episode of a small amount of bright red blood on otherwise normal stool may resolve on its own, particularly if your cat is eating, drinking, and behaving normally. But certain combinations of symptoms indicate your cat is losing significant blood or has a serious underlying condition. Pale gums are a sign of anemia or shock, meaning your cat has already lost a concerning volume of blood internally. Lethargy, especially if your cat is hiding or unresponsive to food, suggests the body is compensating for a serious problem. Repeated episodes of bloody diarrhea, blood mixed throughout the stool rather than just on the surface, dark tarry stool, or bleeding accompanied by vomiting all warrant prompt veterinary evaluation.
Your vet will likely start with a physical exam and fecal test to check for parasites. Depending on the findings, next steps can include blood work to assess clotting function and organ health, abdominal imaging to look for masses or obstructions, and in some cases colonoscopy with biopsy to examine the intestinal lining directly. The cause determines the treatment, which is why identifying the source of bleeding matters more than stopping it at home.