Diarrhea is not a disease; rather, it is a symptom of many different diseases. Many mild cases of diarrhea can be resolved quickly with simple treatments. Rarely, diarrhea is the result of a fatal illness, such as cancer. Even diarrhea caused by mild illnesses may result in death if treatment is not begun early enough to prevent severe fluid and nutrient losses.

We attempt to classify each case of diarrhea as either a major problem or a minor problem and localize the source of the diarrhea to the small intestine or large intestine (or both). It is important to determine how long the diarrhea has been present and whether the cat has lost weight with diarrhea. We use all of the information gathered to formulate a plan for diagnostic and therapeutic procedures.

Which cats are likely to get diarrhea?

Some potential risk factors for diarrhea include dietary indiscretion, exposure to cats with certain illnesses, a positive status for feline leukemia virus or feline immunodeficiency virus, and travel to areas of endemic fungal infection.

What are the clinical signs?

With minor causes of diarrhea, the cat may have no signs of illness other than the loose stool.

Major causes of diarrhea result in the cat being visibly ill and exhibiting several, but usually not all, of the following:

  • Vomiting
  • Dehydration
  • Loss of appetite
  • Abdominal pain
  • High fever
  • Lethargy
  • Bloody and/or watery diarrhea

What are the possible causes?

Minor causes of diarrhea include

  1. Stomach or intestinal viruses
  2. Intestinal parasites
  3. Dietary indiscretions (such as eating garbage or other offensive or irritating materials)

Major causes of diarrhea may include

  1. Inflammatory bowel disease
  2. Neoplasia
  3. Fungal or bacterial infection
  4. Hyperthyroidism
  5. Loss of pancreatic function

How is the cause of diarrhea diagnosed?

If your cat does not exhibit the clinical signs of a major cause of diarrhea, we classify it as a minor cause. A minimum number of tests are performed to rule out common causes of minor diarrhea. These may include a physical examination, multiple fecal exams for parasites, and possibly an x-ray.

For cats who are visibly ill with diarrhea (major case), diagnostic procedures are usually implemented quickly. We perform a series of tests that allow us to make a diagnosis so that specific treatment may be initiated. These tests may include tests for feline leukemia virus and feline immunodeficiency virus, radiography (x-rays) with or without barium, blood tests, stool cultures, biopsies of the intestinal tract, thyroid profiles, and exploratory abdominal surgery. Once a specific diagnosis is made, treatment may include special medications and/or diets, or surgery.

How is diarrhea treated?

With minor cases of diarrhea, treatment may be geared toward one or more of the common causes of uncomplicated diarrhea. Even with negative fecal examinations, many cats with uncomplicated diarrhea are routinely treated for worms. Other therapies often include drugs to control the motility of the intestinal tract, medications that relieve inflammation in the intestinal tract and, often a special diet for a few days. This approach allows the body's healing mechanisms to correct the problem.

With major causes of diarrhea, initial therapy may be supportive; this would include fluid replacement, electrolyte replacement, and perhaps antibiotics. Additional therapy will depend upon the diagnosis.

What is the prognosis?

With minor (uncomplicated) cases of diarrhea, we expect improvement within 2-4 days of initiating therapy. If this does not occur, a change in medication or additional testing may be needed to further define possible causes. Please keep us informed of lack of expected improvement so that we may manage the situation properly.

Can it be transmitted to humans?

Some of the bacterial and parasitic causes of diarrhea are infectious to humans. If any members of your household are also experiencing diarrhea, it is important to let us know. This will allow the veterinarian and physician to work together in managing potentially infectious causes of diarrhea.


Circle each item that applies:


  • Watery stool
  • Stool is about the thickness of pancake batter or pudding


  • Very bloody stool
  • Only sporadic blood present
  • Blood not present in stool
  • Bright red blood present
  • Dark, tarry blood present


  • Entire stool is soft or watery
  • Only portions of the stool are soft or watery
  • Diarrhea with each bowel movement
  • Diarrhea is sporadic (some bowel movements are normal)
  • Only 1 or 2 bowel movements per day
  • More than 4 bowel movements per day


  • Stool is dark brown in color
  • Stool is very pale in color
  • Stool is black and tarry in appearance


  • Thick mucus or pieces of tissue present in stool
  • Loss of bowel control (defecates in the house on the floor)
  • Severe straining when having a bowel movement
  1. Is your cat's appetite normal? If not, is it eating at all?
  2. How long has the diarrhea been present?
  3. Is the diarrhea more severe now than a few days ago?
  4. What have you been feeding your cat during the last week? (Include dog or cat foods, treats, table foods, milk, and anything else that it gets on a daily basis. Also, state what percentage of the diet is each item or category.) Does your cat have access to foods other than what you feed it? If so, what?
  5. Has there been a significant diet change in the last few weeks? If so, does that correspond with the onset of the diarrhea?
  6. Is your cat as active as normal?
  7. Describe any change in water consumption (increased or decreased).
  8. Has vomiting been occurring? If so, how frequently and for how long?
  9. Does your cat go outside your house? If so, does the cat go outside the yard?
  10. Does your cat have access to garbage cans, either within your house or yard or outside your yard?
  11. Does your cat have play-toys that could have been swallowed?
  12. Does your cat have access to sewing materials, such as thread or needles, or rubber bands, or string?
  13. Do you have other dogs or cats that live with this one? If so, does the other pet have diarrhea?
  14. Do any of the members of your family currently have a diarrhea problem?
  15. At what phone number may we reach you or your spouse today if we need further information?

Printable PDF - Cat Diarrhea