Chronic Diarrhea in Cats

Stephanie Howe, DVM
Written by:
Published: September 12, 2022
Chronic Diarrhea in Cats

What Is Chronic Diarrhea in Cats?

The color, consistency, and frequency of your cat's bowel movements are indicators of their digestive health and overall well-being. Stool in a cat should appear brown and well formed, easily scooped but not too firm. 

When the food your cat eats doesn’t spend enough time in the intestines, the absorption of nutrients, electrolytes, and water is diminished and it results in stool that is soft, mushy, liquid, or watery. This softer stool is called diarrhea.

Chronic diarrhea is diarrhea that reoccurs frequently over time. It is stool that is consistently softer than normal and continues for several weeks or longer.

Chronic diarrhea affects cats of all breeds and ages and can have many causes. Kittens, senior cats, and cats that are immunocompromised are most susceptible to serious complications of chronic diarrhea and should be examined by a veterinarian as soon as possible.

Small intestinal (small bowel) diarrhea and large intestinal (large bowel) diarrhea are two terms used to indicate what portion of the intestines is affected.

In small bowel diarrhea, there is a larger volume of stool than normal. If blood is present in the stool, it will look black or tarry.

In large bowel diarrhea, stool is usually smaller than normal, and frequency is increased. If blood is present in the stool, it will look bright red. Cats with this type of diarrhea may appear to strain to defecate.

Symptoms of Chronic Diarrhea in Cats

Symptoms of chronic diarrhea depend on the cause. If your cat has diarrhea (this may be soft-to-watery in consistency) that lasts longer than 24-48 hours, or if they are showing any of the following symptoms, they should be examined by a veterinarian as soon as possible.

  • Abnormal stool color (dark, tarry stool)

  • Fresh blood in the stool

  • Straining to defecate

  • Increased frequency of defecation

  • Weight loss

  • Increased or decreased appetite

  • Decreased energy level

  • Vomiting

  • Dehydration

  • Increased flatulence

Causes of Chronic Diarrhea in Cats

Chronic diarrhea in cats is caused by:

  • Disease that affects the intestines or gastrointestinal system

  • Disease that affects another part of the body, and diarrhea occurs as a result

Intestinal Disease

Nonintestinal Disease

How Veterinarians Diagnose Chronic Diarrhea in Cats

Keeping a detailed history of your cat's bathroom habits can be very helpful in diagnosing their diarrhea. This should include the length, appearance, and frequency of the diarrhea, and anything that seems to improve or worsen it.

The following tests may be used to diagnose your cat’s diarrhea:

  • Complete blood count/blood chemistry test: looks at red and white blood cell counts, electrolytes, and internal organ function

  • Thyroid test: checks your pet’s thyroid hormone levels; thyroid helps regulate metabolism

  • Fecal test: checks for intestinal parasites and infectious organisms

  • Urinalysis test: looks for bacteria, protein or glucose in the urine

  • Infectious disease test: checks for feline immunodeficiency virus and feline leukemia virus

Depending on your cat’s symptoms and results of previous testing, your veterinarian may conduct more tests, such as:

  • Fecal PCR test: checks for DNA of specific intestinal parasites, bacteria, and protozoans

  • Absorption test: a blood test that checks how well the intestines absorb cobalamin (vitamin B12) and folate (vitamin B9), and feline trypsin-like immunoreactivity (fTLI), which ensures the pancreas is producing the digestive enzyme trypsinogen

  • X-rays: are most often used for partial intestinal obstruction

  • Abdominal ultrasound: evaluates the intestines, lymph nodes, liver, kidneys, and spleen

  • Endoscopy/colonoscopy: a camera-tipped tube is inserted from the throat or rectum to look at the surface of the digestive tract (stomach and upper intestines or colon). A sample of your pet's stomach or intestinal wall may be sent to the laboratory for testing. This test requires anesthesia.

  • Biopsies: samples of your pet’s lower intestinal tract are obtained surgically. This procedure requires anesthesia.

Treatment of Chronic Diarrhea in Cats

Treatment of chronic diarrhea in cats greatly depends on its cause. Your vet will identify any underlying causes and will recommend specific treatments for nonintestinal-related diseases such as hyperthyroidism or diabetes, as well as those that are intestinal-related. Your cat may need digestive support medications or supplements such as probiotics or vitamin B12.

Depending on your cat’s condition, your vet may recommend a diet trial. Novel or hydrolyzed proteins are often the best option for this type of diet. (A novel protein diet is a diet containing only proteins that your pet has never eaten before). A prescription diet may also be needed.

A diet trial typically lasts from 3 to 8 weeks. Pets should only eat that diet during this time. Currently available blood tests for food allergies in cats are not as reliable as a diet trial.

What Should I Feed a Cat with Chronic Diarrhea?

Depending on test results, there are two main treatment options for cats with chronic diarrhea:

  1. Low-fat/high-fiber diet:  recommended for cats with uncomplicated pancreatitis, infections, mechanical obstructions, or thyroid disease

  2. Novel protein/hydrolyzed diet: recommended for immunocompromised cats, and those with inflammatory bowel disease, triaditis, and vitamin deficiencies

Ask your veterinarian what type of diet is best for your cat.

Recovery and Management of Chronic Diarrhea in Cats

Recovery time depends on the primary cause of your cat's chronic diarrhea. In some cats, general changes in diet and digestive support may improve fecal firmness. Cats with diarrhea caused by specific issues such as intestinal parasites, unregulated diabetes, or thyroid disease can have their diarrhea resolved within weeks of treatment, while others may need lifelong therapy to control their symptoms.

Are There Home Remedies for Cats with Chronic Diarrhea?

Cats with a chronic disease, senior cats, kittens, and pregnant cats should all be examined by a vet immediately after chronic diarrhea is noted. Also, if your cat’s diarrhea contains blood and is accompanied by vomiting, weight loss, lethargy, or lack of appetite, take them to a vet as soon as possible.

For those cats that continue to eat well, have a good weight, and have normal energy levels, a few options are available for you to try at home:

  • Diet trial using an over-the-counter “sensitive stomach” food

  • Fiber supplement or canned pumpkin

  • Feline-specific probiotics

If these options do not help your pet's stool return to normal in a few days, or if additional symptoms arise, take your cat to your primary care veterinarian as soon as possible.

Never give your cat over-the-counter anti-diarrheal medications for humans, like Pepto Bismol and Imodium, without first asking your veterinarian. These medications can have severe side effects in pets if not used properly.

Featured Image: iStock.com/Nils Jacobi


Help us make PetMD better

Was this article helpful?

Related Articles

Cat Constipation
Cat Constipation
Connect with a Vet

Subscribe to PetMD's Newsletter

Get practical pet health tips, articles, and insights from our veterinary community delivered weekly to your inbox.