Cat Diarrhea: Causes and What to Do About It

Why Does My Cat Have Diarrhea?

Diarrhea in cats is a common symptom of many diseases, and it is never normal. The causes range from harmless to deadly.

Kittens, senior cats, cats with chronic disease, and pregnant cats are all at increased risk of death-related to complications from untreated diarrhea.

If diarrhea is not self-resolving within a 24-hour period, especially in these populations, you should seek out veterinary care.

Stool consistency suggests the degree of severity to your veterinarian. Liquid diarrhea is concerning because it dehydrates and malnourishes an animal quickly. Soft, formed stool is generally less severe but should still be assessed by a veterinarian.

Vomiting in conjunction with diarrhea is always an emergency and should be addressed by a veterinarian. Stomach upset in cats often results in this combination.

With or without diarrhea, vomiting suggests potentially life-threatening disorders such as:

• Intestinal obstruction

• Toxin ingestion

• Organ failure (such as kidney disease)

• Pancreatitis

• Diabetic ketoacidosis

• Addisonian crisis

• Severe infection

• Severe food allergies

Types of Cat Diarrhea

Let’s discuss at a few common types of cat diarrhea.

Red or Bloody Cat Diarrhea

Bloody diarrhea is always concerning and should be addressed by a veterinarian as soon as possible.

Dark red or black discoloration of feces indicates upper GI bleeding (stomach, small intestine) and blood digestion.

Bright red coloration within the feces or coating the feces is a sign of lower intestinal tract bleeding (colon, rectum).

Mucus-coated feces indicates possible inflammation of the digestive system, dehydration or parasitic infection.

Yellow or Green Cat Diarrhea

Discolored feces can sometimes be related to something your cat has recently ingested. For example, grass or green-colored material such as green kibble or green treats may cause green discoloration, which is not always a medical concern, although some animals with green feces have gallbladder disease.

Yellow feces can be an emergency related to liver disease or failure, zinc poisoning, immune-mediated hemolytic anemia, or an overgrowth of certain bacterial pathogens.

Acute vs. Chronic Diarrhea in Cats

Cat diarrhea can be acute or chronic. Acute means that the diarrhea just happened suddenly or doesn’t go on for long period of time.  

Acute diarrhea in cats is characterized by diarrhea lasting less than 14 days (about two weeks).

Chronic diarrhea in cats is characterized as lasting for two to three weeks or longer.

In most cases of acute diarrhea, the body’s own healing mechanisms (such as the immune system) can help cats heal in addition to conservative treatment—such as probiotics and other supplements—or even a short-term diet change.

Some cases of acute diarrhea might need short term oral medications.

Chronic diarrhea will need to be investigated with diagnostic testing and even hospitalization. Typically, chronic diarrhea often results in a medical diagnosis or long-term treatment plan.

Cat Diarrhea Causes

The cause of cat diarrhea depends on whether a cat’s diarrhea is acute or chronic, as there are different sets of possible causes for each.

Acute Cat Diarrhea Causes

There are six main categories when it comes to the cause of acute diarrhea in cats:

• Infectious (parasitic, protozoal, bacterial, fungal, or viral)

• Inflammatory (such as food allergies)

• Metabolic or endocrine (such as diabetes or hyperthyroidism)

• Cancerous

• Obstructive

• Poisonous/toxic

Treats or sudden diet changes can also cause diarrhea in cats. It’s important to make sure that the products that you feed to your cat are carefully inspected and introduced slowly.

• Treats or new foods (canned or dry) can cause diarrhea if:

• They are contaminated

• They are suddenly introduced

• They contain ingredients that are toxic to cats

• They contain ingredients that cats are allergic to

Chronic Cat Diarrhea Causes

Causes of chronic diarrhea include:

• Resistant infections

• Chronic inflammatory disease

• Poorly managed metabolic or endocrine disease

• Congenital disease (defect or virus present at birth)

• Cancer

Chronic diarrhea in cats is of particular concern because it can cause life-threatening complications. Long-lasting diarrhea that is resistant to treatment can often be multifactorial, with multiple treatments needed for complete resolution.

If no improvement is seen in your cat’s diarrhea within two to three days of initiating therapy, you should contact your veterinarian to check for potential complicating factors.

Diagnosing Diarrhea in Cats

If you are seeing your veterinarian for your cat’s diarrhea, it’s always advised to bring a fresh stool sample for your vet to analyze for intestinal parasites or other infectious causes.

Your veterinarian may run fecal tests that include fecal flotation, antigen testing, cytology, and culturing to screen for infectious or inflammatory disease.

Blood work evaluates for metabolic or systemic causes of diarrhea and assesses the consequences of cat diarrhea, such as dehydration or anemia.

Abdominal ultrasound, radiology, and endoscopy can be used to check for foreign body ingestion or cancer as causes of cat diarrhea.

Cat Diarrhea Treatment

Do not try to use Pepto-Bismol®, Kaopectate®, or any other human medications to treat your cat’s diarrhea. These can be dangerous for pets.

If your cat’s diarrhea is yellow, bloody, chronic, coated in mucus, or accompanied by vomiting, contact your vet right away for treatment.

You should also call your vet if you have a kitten, senior cat, a cat with a chronic disease, or a pregnant cat that has diarrhea for vet treatment.

They can then diagnose the cause and start the related treatment for that cause.

Your cat may need to be hospitalized depending on how severe their diarrhea is and how they are affected.

Hospitalization is recommended if:

• If your cat is dehydrated

• Your cat isn’t eating well

• They’re vomiting, lethargic and/or not acting normally

Treatments in the hospital would include intravenous (IV) fluids, antibiotics, antinausea medications, and more, based on your cats’ symptoms.

Otherwise, you can increase fiber consumption to treat soft stool at home.

You can ask your veterinarian about the frequency and dosing of canned pumpkin or fiber supplements, and there are some feline-specific over-the-counter fiber products that you can get to increase dietary fiber, as well.

Feline-specific probiotics can also benefit some cats with diarrhea.

If fiber or probiotic formulations are not enough to return your cat’s stool to its normal consistency after one to two days, consult your veterinarian.

Gradual transition of your cat to an over-the-counter diet targeting gastrointestinal health may provide some benefit, but prescription diets are recommended if diarrhea persists.

Recovery and Management of Cat Diarrhea

When your cat is recovering from diarrhea, the goal is to have them feel better as soon as possible with resolution of all symptoms.

This might mean a hospital stay or that they need extra care at home. Making sure they take all medications as prescribed and continue any diet changes as long as your veterinarian recommends.

Transitioning a cat’s diet back to their regular food when they feel better should be done slowly over a week or so.

Depending on your cat’s diagnosis, there might be some long-term diet or supplemental needs or the need to check lab work with your vet on a regular basis.

If you are treating your cat at home, having them in a quiet and comfortable placeto rest and recover is ideal.

If you have other pets, quarantine your cat in a room by themselves with all their needs, such as their litter box and bedding.

If your cat has any abnormal test results—such as intestinal parasites on a fecal, changes to their blood work, or it's simply requested by your vet—make sure to keep up with all follow-up visits even if your cat is feeling better.

Prevention of Cat Diarrhea

Preventing feline diarrhea is possible.

Control underlying diseases such as pancreatitis, irritable bowel syndrome (IBS), hyperthyroidism, or food allergies with appropriate medications and prescription diets, as recommended by your veterinarian.

Do not make sudden diet changes or give your cat human foods or rich or novel treats to avoid cases of acute diarrhea.

Prevention is also possible by keeping up with annual visits and stool checks with your veterinarian to ensure your cat was not exposed to intestinal parasites. This is even more important in cats that are allowed to spend time outside, even if it’s a controlled environment like a catio or porch.

Remember, your veterinarian is your best resource for treating cat diarrhea.