Causes and Treatments of Bloody Stool in Cats Explained in Detail by a Veterinarian

If you notice blood in your cat’s stool, it may be a case of hematochezia (bloody stool).

Seeing blood in their cat’s stool can be quite alarming for any owner. Most cases of bloody stool are caused by an underlying medical condition. It is important to understand the causes and how to respond so that you don’t panic when it happens.

In this article, we will explain the causes and treatments for bloody stool in cats.

Symptoms and Classification of Bloody Stool in Cats

"Bloody stool" refers to more than just stool mixed with blood. The color varies depending on where the bleeding is occurring. Here is a classification of bloody stool by color.

Black Stool

When there is bleeding in the upper gastrointestinal tract, such as the stomach or duodenum, or in the small intestine, the blood is digested and turns black. The resulting stool is black and tarry, classified as "tarry stool" or "melena."

Stool Mixed with Bright Red Blood

If bleeding occurs in the first half of the large intestine, bright red blood will be mixed into the stool. This is what is typically thought of as common bloody stool.

Bright Red Blood Coating the Stool

If bleeding occurs in the second half of the large intestine or the anus, blood will be present as a coating on the surface of the stool.

What Causes Blood in a Cat's Stool?

While most cases of bloody stool in cats are caused by medical conditions, factors such as stress, diet, or ingesting foreign objects can also be culprits.

We will explain each of these below.

Medical Conditions

The vast majority of cases are due to underlying diseases. In some cases, these conditions can be highly urgent or even fatal.

Gastroenteritis

Causes include viruses, bacteria, drugs, and allergies.

It begins with diarrhea or loose stools, and as the condition worsens, it can lead to bloody stool. Dehydration can result, which can become life-threatening.

Feline Panleukopenia Virus Infection

When kittens are infected with feline panleukopenia virus, they experience severe diarrhea and bloody stool. This virus is highly contagious, and an infection in a kitten can be severe and carries a high risk of fatality.

Parasitic Infections

Parasites in the gastrointestinal tract can cause bloody stool. These include Tritrichomonas, Giardia, hookworms, and Toxoplasma. Because hookworms attach to the small intestine to feed, they can cause black stools.

Tumors

In older cats, blood in the stool may indicate a tumor, such as lymphoma or adenocarcinoma of the gastrointestinal tract. The color of the blood can vary depending on where the tumor is located.

Symptoms often accompany the bloody stool, such as loss of appetite, weight loss, vomiting, and loose stools.

Constipation

When stool becomes hard due to constipation, it can cause scratches in the rectum or anus during defecation. This leaves blood on the surface of the stool.

Stress

Environmental changes—such as moving house, construction nearby, or a new family member—can cause significant stress for a cat. When stress irritates the gastrointestinal tract, it can lead to bloody stool.

Diet

If a cat with food allergies consumes food containing a trigger, it can lead to allergic gastroenteritis, resulting in loose stool, diarrhea, or blood in the stool.

In addition to stool changes, symptoms can include vomiting, itchy skin, or hair loss.

Ingesting Foreign Objects

There are many things toxic to cats, such as onions, houseplants, and medications. If a cat accidentally ingests these, bloody stool can occur as a symptom of poisoning.

What to Do if Your Cat Has Bloody Stool

Since most cases of bloody stool are caused by medical issues, you should see a veterinarian promptly rather than waiting to see how things progress.

Visit a Veterinary Clinic

Even if your cat seems energetic and has an appetite, you should have them examined if they have bloody stool.

It is recommended to bring a sample of the stool, but try to bring a sample as fresh as possible, as stool older than half a day can lead to inaccurate bacterial or parasite test results.

If you cannot get to the vet immediately, taking a picture of the stool can help the veterinarian understand the color and consistency.

In some cases, cats brought in for "bloody stool" were actually experiencing bloody urine or issues around the anus, such as an anal sac rupture. A proper veterinary examination is essential.

Address Stress

If a veterinary exam suggests that stress-induced gastroenteritis is the cause, take steps to improve the cat’s environment to minimize stress.

Providing places where your cat can retreat or installing a cat tree for vertical activity is beneficial. If the cat is under extreme tension, your vet may prescribe temporary anti-anxiety medication. There are also supplements available to help relieve stress; consult your veterinarian for advice.

Change Your Cat’s Diet

If the vet determines that food-allergic gastroenteritis is a possibility, they may suggest a hypoallergenic diet. Since the condition is caused by allergens in the food, switching to an allergen-free diet is the standard treatment.

In cases of constipation, your vet may prescribe a therapeutic diet to help make passing stool easier.

Therapeutic diets should be recommended by a veterinarian, so please do not purchase them based on your own judgment.

Summary

Bloody stool in cats is often caused by medical conditions, some of which can be life-threatening if left untreated. Additionally, in the case of viral or infectious diseases, other cats may be at risk of infection.

Do not wait to see if the cat gets better just because they are energetic; if you notice blood in their stool, visit a veterinary clinic immediately.

If an older cat has bloody stool, it could be a tumor. Depending on the tumor, early intervention can lead to a better prognosis.

We strongly recommend scheduling regular health checkups so that you can identify any abnormalities as early as possible.