Bright Red Blood in Cat Stool (Hematochezia)

Last Updated on October 12, 2021 by Julia Wilson

At a glance

About: Bright red blood either through or on the outside of feces is known as hematochezia. It is a sign of bleeding in the lower intestines (colon and rectum).


  • Tumours (benign and cancerous)
  • Colitis
  • Inflammatory bowel disease
  • Bacterial infection (Campylobacter, salmonella, e-coli)
  • Viral infection (panleukopenia)
  • Protozoal infection (cryptosporidium)
  • Intestinal worms (hookworm or roundworm)
  • Blood clotting disorders
  • Anal gland rupture
  • Rectoanal polyps
  • Constipation
  • Diarrhea

Diagnosis: Thorough physical examination along with baseline tests including complete blood count, biochemical profile and urinalysis. Additional tests may include imaging, fecal exam, biopsy, colonoscopy and coagulation profiles.

Treatment: Depends on the underlying cause.


It is always alarming when we discover blood in your cat’s stool, but in a lot of cases, the cause is minor and transient. Blood in the cat’s stool may be light, with just a smear or speck or heavy and it may be with or without accompanying symptoms.

  • Melena – Tarry black stools are associated with upper gastrointestinal tract bleeding including the esophagus, stomach, and duodenum, but bleeding may also originate from the nose or mouth. Bacteria break down the blood in the stomach before it moves to the lower intestinal tract and out of the anus.
  • Hematochezia – Bright red blood which is associated with lower intestinal (colon and rectum) and anal bleeding. This type of blood in the stool is much more apparent than melena. It may be throughout the feces or just on the outside.

The occasional sighting of bright blood in the feces is usually insignificant, however, if it lasts longer than a day if there is a large volume of blood passed and if other symptoms are also present, see your veterinarian.

This article focuses on bright red blood in the stool.


Parasitic infection

Cryptosporidium or intestinal worms. Cryptosporidium causes inflammation of the intestines which leads to bleeding. Parasitic worms such as hookworm or roundworms suck the blood from the intestinal wall, resulting in blood in the stool. Parasites are one of the most common causes of blood in stool in kittens.


Medication to treat parasitic worms. All cats, even those who live indoors should be regularly treated for parasitic worms.

There are no effective medications to treat cryptosporidium. However, some veterinarians will prescribe antiprotozoal drugs to immunocompromised cats. Supportive care is the mainstay of treatment for cryptosporidium including fluids to treat dehydration and anti-diarrheal medications.

Bacterial infection

Bacterial infection, salmonella, campylobacter, and e.coli. These infections can cause inflammation in the intestinal tract which over time can cause bleeding.


Oral antibiotics and supportive care where necessary, this may include fluids to treat dehydration. Your cat may be put on a bland diet for a few days to rest the gastrointestinal tract if vomiting and diarrhea have occurred.


Panleukopenia (feline parvovirus) is a highly infectious viral infection that affects white blood cells. Kittens are most at risk of this disease. Symptoms can include loss of appetite, listlessness, vomiting, bloody diarrhea, and dehydration.


The prognosis for kittens is poor, especially in younger kittens. There are no medications that can kill the virus; intensive supportive treatment is provided which gives the cat’s immune system to fight the virus.

  • Blood transfusions if the white blood cell count drops significantly.
  • Antibiotics to fight off secondary bacterial infections which can develop due to decreased white blood cells.
  • Anti-viral medications (omega-interferon).
  • Intravenous fluids to correct dehydration and electrolyte imbalances.
  • Painkillers.
  • Medications to control vomiting.
  • Vitamin B and C injections.
  • Nutritional support (feeding tube).
  • Plenty of tender loving care is vital as cats can lose their will to live.


Constipation is the infrequent passage of hard and dry stools. There is no set number of bowel movements a cat must take in a day, but one to two is average. Constipation can affect cats of any age although it is seen more commonly in middle-aged to elderly cats.


Mild constipation:

Mild cases of constipation without accompanying symptoms such as vomiting or depression may be treated on an outpatient basis at home by providing extra fibre, laxatives, stool softeners and increasing water consumption:

Severe constipation:

Treatment for severely constipated cats requires hospital treatment. Never administer an enema at home. This procedure is invasive and cats do not respond well. Many of the ingredients in human enemas are toxic to cats.

  • Enema or manual extraction of the feces.
  • Rehydration with intravenous fluids.


Also referred to as malignant neoplasms or malignant tumours, cancer is the uncontrolled division of cells that normally should be restrictive in their growth. Cancers that have the potential to cause blood to appear in the stool include intestinal cancer, colon cancer and anal gland cancer.


Where possible, surgery to remove cancer, and/or chemotherapy and radiotherapy to kill remaining cells or where surgery isn’t possible.

Rectoanal polyps

Benign (non-cancerous) growths can occur on the wall of the lower intestine or around the anus. Polyps are extensions of the innermost tissue, and are either attached by a stalk or protrude directly out of the lining.


Surgery to remove polyps or tumours. Chemotherapy as a follow up in some cases.

Anal sac disease

The anal sacs (anal glands) are two small sacs located on either side of the anus at the five and seven o’clock position. Their role is similar to scent glands, and they secrete an oily, foul-smelling substance that helps other cats to identify the individual. Anal sac disease begins when the secretions of the anal glands become thickened and impacted which causes inflammation. If the anal sacs are not treated at this point, an infection can develop and form an abscess. This, in turn, can rupture through the adjacent skin.


If the anal glands are simply impacted and haven’t progressed to infection and or abscess, it may be possible to express the glands manually. Your veterinarian will need to do this, and it involves inserting a finger into the anus and gently applying pressure.

If the anal sacs have become infected or abscessed, lancing and extraction of the infected material will be necessary. This is followed by flushing and antibiotics are instilled into the sacs to treat an infection.

If your cat has repeated problems with its anal glands, surgical removal may be necessary.

Food allergy

Food allergies are the third most common type of allergy in cats (behind flea allergy and inhalant allergy). The most common causes of food allergies are fish, beef, chicken, eggs, and wheat. Cats become allergic to foods they have eaten for an extended period (usually two years or more). There is no breed, sex or age predilection. Cats with other allergies (such as inhalant) may be at higher risk of developing food allergies. There appears to be a genetic component.


Inflammatory bowel disease

Inflammatory bowel disease is a group of disorders caused by the infiltration of inflammatory cells (white blood cells) in the mucosa of the gastrointestinal tract.



  • A highly digestible, low-fat diet containing a novel protein.
  • A high fibre diet in cats with colitis.

Medical management:

  • Corticosteroids: Prednisone is the drug of choice (as well as dietary therapy) for all types of
    inflammatory bowel disease. These drugs have anti-inflammatory and immunosuppressive properties.
  • Antibiotics: Metronidazole is an antibiotic with anti-inflammatory properties and can be used in conjunction with dietary therapy to help manage IBD.
  • Other immunosuppressive drugs: Azathioprine (brand name Imuran) is an immunosuppressive drug that can be used in combination with corticosteroids. There can be side effects; it is therefore only used as third-line therapy in refractive (unresponsive to diet and corticosteroids alone) IBD. Cats on this drug should have a CBC every week for the first month and every 2-3 weeks while the cat is on the drug.
  • Sulfasalazine: This anti-inflammatory medication is the drug of choice for lymphatic-plasmacytic colitis.

Blood clotting disorders

Several disorders in which the blood loses its ability to form clots which are necessary to stop bleeding (both internal and external, such as when the cat cuts itself). This process is known as coagulation. Thrombocytopenia (low blood platelets) or hemophilia are two conditions in which the cat’s blood loses its ability to clot. Certain poisons, such as rat poison can cause the blood to lose its ability to clot properly.


The goal of treatment is to find and address the underlying cause (in the case of thrombocytopenia). Supportive care such as whole blood or plasma transfusions may also be necessary as well as Vitamin K injections.

If rat poison has been ingested, treatment will include the following:

  • If ingestion has occurred recently, then your veterinarian will induce vomiting and pump the stomach.
  • Activated charcoal binds to the toxin, preventing further absorption.
  • Vitamin K injection will help to form clotting factors.
  • If bleeding is severe, your cat may require a blood transfusion.
  • Once your cat is stable, he will be sent home with an oral dose


Colitis is the inflammation of the lining of the colon (large intestine). It may be chronic, symptoms have been present for 14 to 21 days, or acute (sudden onset). The colon is responsible for extracting water from the feces and storing fecal matter before evacuation (bowel movement). Cancer, food allergies, parasites, cancer, dietary indiscretion and stress can all cause colitis.


Identify and eliminate the cause as well as give supportive care. This may include:

  • Provide a high fibre diet if the colon is affected.
  • Anti-inflammatory medications to reduce inflammation.
  • Supportive care such as fluids to treat dehydration and nutritional support.

Specific treatments:

  • De-worming medications for parasitic worms.
  • Antibiotics for bacterial infection.
  • Surgery and/or chemotherapy for cancer.
  • Feed a high digestible, low-fat diet that contains a novel protein.
  • Reduce stress in the home, address the cause where possible and avoid a change in routine.

Other symptoms to watch for

Watch for other signs as this information can assist your veterinarian in determining the cause. Accompanying symptoms may include the following:

Often there will be no accompanying symptoms, but this doesn’t rule out an underlying problem. If you notice blood in your cat’s stool more than once or twice, it will need to be investigated, even without other symptoms present.


If possible, bring along a stool sample or take a photo to show your veterinarian. If you suspect your cat has ingested poison, bring along the packaging if possible. Your veterinarian will perform a complete medical and rectal examination and obtain a medical history from you.

Questions the veterinarian will ask:

  • Is it firm and well-formed with blood on the surface?
  • This type of stool may be due to polyps, constipation or anal gland disorders.
  • Is it loose with blood mixed on the surface or mixed into the stool?
  • This may be suggestive of an inflammatory or irritative disorder although cats with colitis can also pass firmly formed stools also.
  • Has your cat had any recent medications?
  • Prescribed, non-prescribed and supplements.
  • When did you last worm your cat?

Cats who pass firm stools most often have constipation, polyps or anal gland issues. Whereas soft/loose stools are typically due to inflammation or infections. He will need to perform further tests to determine the cause of bleeding.

Diagnostic workup:

  • Baseline tests: Complete blood count to check for infection, inflammation, anemia and evaluate the cellular component of blood, biochemical profile to assess the overall health of the cat and urinalysis.
  • Rectal examination: The veterinarian inserts a finger into the rectum to feel for abnormalities such as tumours and polyps.
  • Fecal examination to check for parasites.
  • Abdominal x-rays: To look for growths, foreign bodies and check the internal organs
  • Abdominal ultrasound: To look for growths, foreign bodies and check the internal organs
  • Biopsy – Surgical removal of a small sample of any suspicious lumps for microscopic evaluation.
  • Colonoscopy – Visual examination of the colon with an endoscope while the cat is under sedation.
  • Coagulation profiles – To evaluate your cat’s blood clotting ability


  • Slippery elm: A herbal remedy that has many medical uses. It contains mucilage (a gelatinous substance) which coats and soothes the intestines and stomach as well as increasing mucus secretion which protects the gastrointestinal tract.
  • Probiotics: Yoghurt contains a type of bacteria known as lactobacillus; these bacteria usually reside in the intestines, helping with the digestion of food. Sometimes the natural flora of the gut is thrown out of balance (for example if your cat is on a course of antibiotics), and this can lead to opportunistic and pathogenic strains of bacteria taking hold.