# Cat Diarrhea On and Off: Causes of Intermittent Loose Stool Intermittent loose stool in cats usually means the colon is being irritated by something that comes and goes, such as a food ingredient, a parasite, or low-grade inflammation. Because the triggers are often subtle, the pattern of episodes matters as much as any single stool sample. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Diarrhea that starts and stops over weeks or months is called chronic or intermittent, and it is different from a single 24-hour upset. - The large intestine controls water and salt balance and stores stool, so when it is damaged by illness, parasites, or other causes, diarrhea is often the result [1]. - Common triggers include food sensitivity, intestinal parasites, and inflammatory bowel disease, and more than one can be present at once. - Keep a simple log of dates, stool consistency, diet, and any vomiting or weight change, because your veterinarian will rely on that history. - Do not give human anti-diarrheal medicines or leftover antibiotics, since the dose and the drug choice depend on your cat's weight and diagnosis. ## What Intermittent Cat Diarrhea Actually Looks Like Owners often describe cat diarrhea on and off as "good days and bad days." One week the litter box looks normal, then you find a soft pile, then things firm up again without any obvious reason. Some cats have sudden cat diarrhea out of nowhere after months of normal stools. The look of the stool gives your vet useful clues. Large bowel diarrhea tends to be small in volume, passed often, and may contain mucus or fresh blood. Small bowel diarrhea tends to be larger in volume, less frequent, and sometimes paler or greasy. Chronic diarrhea in cats is often classified as small bowel or large bowel based on these clinical signs, and the two patterns point toward different underlying problems [2]. Normal cat stool is formed, log-shaped, and easy to scoop. A healthy cat passes stool roughly once or twice a day, though this varies with diet and individual cats. Soft stool that happens once after a diet change or a stressful day is usually not a concern. Stool that is loose on and off for more than a week or two deserves a veterinary visit. ## Why Does My Cat Have Diarrhea That Comes and Goes? Intermittent cat diarrhea has many possible causes, and the cause is often not obvious from the stool alone. Inflammation of the colon, called colitis, may be short-term or long-term, and in most cases the cause is unknown [1]. Bacterial, parasitic, traumatic, kidney-related, and allergic causes are all suspected, along with an overreaction of the immune system in the colon [1]. Diet is a major player. A food sensitivity can cause signs that wax and wane, especially if your cat eats a mix of foods or gets table scraps. Your veterinarian may use trials with specific foods to diagnose some causes of colitis [1]. Nutritional management is also a core part of long-term treatment for chronic diarrhea, not an add-on [2]. Parasites and infectious agents are another common thread. In one study of 493 cats with chronic diarrhea, feline coronavirus was found in about 65 percent of them, and Clostridium perfringens toxin DNA was found in about 54 percent of samples [3]. Giardia was detected in about 8 percent of samples [3]. Those numbers do not mean every cat with loose stool has an infection, but they show how often a lab test changes the plan. Chronic enteropathy is an umbrella term for gastrointestinal disease lasting at least three weeks. The most common final diagnoses are inflammatory bowel disease and alimentary small cell lymphoma [4]. Changes in the gut microbiome and in the fatty acids the bacteria produce are thought to play a role in these conditions [4]. | Cause | Typical clues | How urgent | |---|---|---| | Food sensitivity or diet change | Loose stool that improves then returns when a food is reintroduced, normal appetite and energy | Routine visit, sooner if weight loss | | Intestinal parasites (Giardia, others) | Soft or mucusy stool, possible gas, sometimes normal energy, may affect other pets | Routine visit with a fecal test | | Inflammatory bowel disease or chronic enteropathy | Weeks of on-and-off diarrhea, weight loss, vomiting, sometimes pica (eating non-food items) | Prompt visit, usually within days | | Feline coronavirus or Clostridium perfringens | Found on fecal PCR panels, often alongside other findings, more common in cats under 1 year [3] | Prompt visit if diarrhea persists | | Stress or sudden routine change | Loose stool after travel, new pet, or boarding, resolves in a day or two | Monitor, call if it lasts | | Foreign body or pica | Vomiting, appetite change, eating string, plastic, or fabric | Emergency if vomiting or pain | Pica, which is eating non-food items, may itself be a sign of chronic enteropathy. In one review, all 41 animals that had gastrointestinal biopsies showed chronic enteritis, and 80 percent had chronic gastritis [5]. If your cat chews on plastic or fabric along with having loose stool, mention it to your vet. ## Red Flags That Mean Emergency Care Now Some signs mean you should stop reading and call an emergency clinic. - Blood in the stool that is more than a streak, or black tarry stool - Repeated vomiting, especially if your cat cannot keep water down - A swollen, painful belly, or crying when you touch the abdomen - Weakness, collapse, pale gums, or heavy breathing - Straining to defecate with no stool produced, which can suggest a blockage - Known or suspected swallowing of string, toys, or bones - Diarrhea in a kitten under 8 weeks, or in a cat with a chronic illness such as kidney disease or diabetes Kittens and senior cats dehydrate fast. A cat that is hiding, not eating, or losing weight needs to be seen the same day. ## Safe Things You Can Do at Home While You Wait You cannot diagnose intermittent cat diarrhea at home, but you can make the veterinary visit more productive and keep your cat comfortable. **Track the pattern.** Write down the date and time of each loose stool, what it looked like, and whether it was small and frequent or large and watery. Note vomiting, appetite, water intake, energy, and weight if you can weigh your cat on a baby scale. This log often reveals the trigger. **Keep the diet steady.** Sudden switches between brands or flavors can cause loose stool on their own. If your cat is already on a food your vet recommended, do not change it before the appointment unless your vet tells you to. If you are feeding several foods, write down exactly what and how much. **Do not fast your cat.** Cats can develop serious liver problems if they stop eating for even a couple of days. Offer small, frequent meals of the food your cat normally eats. **Never give human medications.** Loperamide, bismuth, and human antibiotics are not dosed for cats without veterinary guidance. Some are toxic to cats. Your veterinarian calculates any dose from your cat's weight and health. **Keep water easy to reach.** Offer fresh water in several spots, and consider adding a little warm water to canned food to support hydration. **Separate litter boxes.** If you have multiple cats, a separate box helps you confirm which cat has the loose stool. For more on what mucus in the stool can mean, see [Cat Diarrhea with Mucus: Causes and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-with-mucus-causes-when-to-worry). If your cat is acting completely normal between episodes, [Cat Diarrhea but Acting Normal: When to Monitor and When to Call](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-acting-normal-when-to-monitor) walks through that specific situation. ## What Your Veterinarian Will Check and Test Your veterinarian will start with detailed questions about your cat's history and a full physical examination [1]. Bring your log. The timeline of episodes often narrows the list of causes faster than any single test. Expect a fecal test first. A fecal flotation or PCR panel checks for parasites and infectious agents, including Giardia and coronavirus [3]. Because more than one pathogen can be present at the same time, a negative test for one organism does not rule out others [3]. Blood work and urine testing help rule out kidney disease, thyroid problems, and other conditions that can cause loose stool. Your vet may also recommend abdominal x-rays or ultrasound, and in some cases endoscopy or biopsies to look at the intestinal lining directly [1]. If food sensitivity is suspected, your vet may recommend a diet trial using a specific food for a set period [1]. This only works if the trial diet is fed exclusively, with no treats, table food, or other pets' food. Nutritional management is a long-term strategy for chronic diarrhea, and it often takes weeks to months to see full improvement [2][6]. Treatment depends on the diagnosis. Some cats need parasite treatment, some need a prescription diet, and some need medication to control intestinal inflammation. In one reported case, a cat with chronic nonresponsive enteropathy improved after being transitioned to a high-protein, low-carbohydrate commercial veterinary therapeutic diet, with psyllium husk later added to improve stool quality [6]. Soft stools can persist for months even with good management, so patience matters [6]. If your cat also vomits, see [Cat Vomiting and Diarrhea: When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-vomiting-diarrhea-when-to-worry). For a broader overview of causes and home care, [Cat Diarrhea: Causes, Home Care, and When to Worry](/knowledge/veterinary-medicine/online-vet-and-care-costs/cat-diarrhea-causes-home-care) is a good next read. ## Preventing and Monitoring Intermittent Cat Diarrhea You may not be able to prevent every episode, but you can reduce triggers and catch problems earlier. **Change food slowly.** If you must switch diets, do it over 7 to 10 days, mixing increasing amounts of the new food into the old. **Stick with one primary diet.** Rotating many foods makes it hard to identify a trigger and can upset the gut microbiome. **Control parasites.** Keep your cat on a veterinarian-recommended parasite prevention plan, especially if your cat goes outdoors or lives with other pets. **Reduce stress where you can.** Keep litter boxes clean, provide hiding spots, and introduce new pets or changes gradually. **Weigh your cat monthly.** A kitchen scale or baby scale works well. Gradual weight loss is easy to miss and is one of the most useful signs of chronic enteropathy. **Recheck with your vet.** Chronic diarrhea often needs follow-up visits and repeat fecal tests, especially if signs return after treatment. ## Limitations and When to Contact a Veterinarian This article cannot tell you what is causing your cat's diarrhea. Only a veterinarian who examines your cat and runs tests can do that, and individual cases always need that evaluation. Call for an emergency visit now if you see heavy bleeding, repeated vomiting, a painful or swollen abdomen, collapse, or straining with no stool. Call the same day if your cat stops eating, is hiding more than usual, has lost weight, or is a kitten, senior, or cat with another chronic disease. Schedule a routine visit within a few days if the loose stool has lasted more than 48 hours, keeps coming back, or comes with mucus, blood streaks, or vomiting. ## Frequently Asked Questions ### Can intermittent diarrhea in cats go away on its own? Sometimes a single mild episode resolves in a day or two, especially after a minor diet change or stress. Diarrhea that comes and goes over weeks is a different situation and usually needs testing. If it has lasted more than 48 hours or keeps returning, book a veterinary visit. ### Is it normal for a cat to have diarrhea once a month? No, a monthly pattern is not normal. It suggests a recurring trigger such as a food ingredient, a parasite, or ongoing intestinal inflammation. Your vet will want a timeline of episodes, a fecal test, and possibly a diet trial. ### Should I fast my cat to settle its stomach? No. Cats should not go without food for more than a short time because they can develop serious liver problems. Offer small meals of the food your cat normally eats and let your veterinarian guide any diet change. ### Can stress cause diarrhea that comes and goes? Yes, stress can trigger loose stool in some cats, especially after travel, boarding, or a new pet in the home. Stress-related diarrhea usually resolves within a day or two once the trigger passes. If episodes continue, look beyond stress for a medical cause. ### Do I need to bring a stool sample to the appointment? It helps a great deal. A fresh sample, ideally less than 12 hours old and kept in a sealed bag in the refrigerator, lets your vet run fecal testing at the visit. If you cannot collect one, your vet can often obtain a sample in the clinic. ## Related Articles - [Why Is My Cat having loose stools with mucus? IBD vs Giardia vs Food Intolerance](/knowledge/veterinary-medicine/symptom-guides/why-is-my-cat-having-loose-stools-with-mucus-ibd-vs-giardia-vs-food-intolerance) - [Cat Diarrhea with Mucus: Causes and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-with-mucus-causes-when-to-worry) - [Cat Diarrhea: Causes, Home Care, and When to Worry](/knowledge/veterinary-medicine/online-vet-and-care-costs/cat-diarrhea-causes-home-care) - [Cat Diarrhea but Acting Normal: When to Monitor and When to Call](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-acting-normal-when-to-monitor) - [Cat Vomiting and Diarrhea: When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-vomiting-diarrhea-when-to-worry) - [Cat Diarrhea and Not Drinking Water: Dehydration Risks and Care](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-not-drinking-water) - [Why Does My Cat Keep Getting Diarrhea? Causes and Next Steps](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-recurring-diarrhea-causes) - [Cat Poop Not Solid: Causes of Loose Stool in Cats](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-poop-not-solid-loose-stool) - [Cat Diarrhea With No Diet Change: Why It Happens](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-diarrhea-no-diet-change) ## References 1. [Disorders of the Stomach and Intestines in Cats - Cat Owners](https://www.merckvetmanual.com/cat-owners/digestive-disorders-of-cats/disorders-of-the-stomach-and-intestines-in-cats). Merck Veterinary Manual. 2. [Feline chronic diarrhea: causes and nutritional management](https://pubmed.ncbi.nlm.nih.gov/42502773/). Veterinary and animal science, 2026. 3. [Feline Coronavirus Prevalence in 493 Cats With Chronic Diarrhea](https://pubmed.ncbi.nlm.nih.gov/41771138/). Journal of veterinary internal medicine, 2025. 4. [Faecal microbiota and fatty acids in feline chronic enteropathy](https://pubmed.ncbi.nlm.nih.gov/38124157/). BMC veterinary research, 2023. 5. [Pica as a clinical sign of a chronic enteropathy in dogs and cats](https://pubmed.ncbi.nlm.nih.gov/40381647/). Journal of the American Veterinary Medical Association, 2025. 6. [Nutritional management of feline chronic enteropathy with evolving dietary response and long-term stabilization](https://pubmed.ncbi.nlm.nih.gov/42544297/). The Canadian veterinary journal = La revue veterinaire canadienne, 2026. ## Further Reading - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)