Finding runny cat poop on the floor outside of your cat’s litter box can be quite distressing, but it’s something that most cat parents will deal with at one point or another during their cat’s life. In fact, according to a report by Healthy Paws pet insurance, stomach issues (including loose stool) were by far the most common illness in cats in 2019, making up a third of all insurance claims. 
Runny poop in cats has many different causes, some harmless and some quite serious. Continue reading to find out the most common causes of diarrhea in cats, what you can do to help your cat feel better, and how to tell when it’s time to call your veterinarian.
Runny Cat Poop: What Does it Look Like?
Runny cat poop, also called diarrhea, loose stool, or watery stool, can take on a variety of appearances. Healthy, normal cat poop should be firm, but not rock hard, and formed into a sausage shape. Anything wetter or mushier is considered diarrhea. The color of your cat’s poop is less important – as long as they are otherwise happy and healthy – and can vary from cat to cat. However, generally speaking, cat poop is brown to dark brown.
If your cat has runny poop, it’s important to take note of the exact consistency and appearance. This may give you a hint as to the severity of the problem and guide treatment if you need to take your cat to the veterinarian.
Decoding Cat Diarrhea: 6 Causes of Runny Cat Poop
Here are a few potential causes of runny cat poop:
If you recently ran out of your cat’s usual food and had to switch to a new brand or flavor, it may have caused runny poop. Your cat has trillions of microorganisms, including bacteria and viruses, that normally inhabit their digestive tract (gut microbiome) and aid in turning food into fuel and getting rid of the waste in the form of poop. When cats are fed a consistent diet, their gut microbiome adapts to digesting that particular food. In turn, when a completely different food is fed abruptly, these flora are often less capable of digesting the new food, resulting in diarrhea. 
If your cat sneaks a bite of dinner off of your plate, you give them a table scrap they don’t usually eat, or they eat something out of the kitchen trash can, this can also lead to loose stools.
Infections with different parasites, bacteria, or viruses are a common cause of runny poop in cats, especially in kittens and cats who spend time outdoors. Common parasites that cause diarrhea in cats include:
Viruses that cause runny cat stool include parvovirus and feline coronavirus, while some common bacterial causes are due to Salmonella and Clostridium infections.
Just as a stressful week at work may cause us to have an irritable bowel, stress can also cause an upset tummy for your cat. Sources of stress in cats aren’t always obvious to pet parents but can range from loud construction going on next door to a change in your work schedule.
Cats will often help themselves to nibbles of the plants in their homes. Many plants are at least mildly toxic to cats, resulting in watery poop when ingested. For this reason, it is important to research any plants in your cat’s environment to ensure that they are not toxic. You can look up plants on the ASPCA website to find out if you should remove them from your home.
Certain foods, such as chocolate, and a variety of over-the-counter medications made for humans are toxic to cats, causing diarrhea in addition to many other symptoms. Again, the ASPCA site is a great place to find out what should be kept out of reach of your cat.
Cats and humans alike can be sensitive or allergic to one or more foods, which can lead to loose stools.
Several chronic diseases affecting different organs in the body can cause runny cat poop, including:
These diseases will typically cause chronic diarrhea (i.e. diarrhea that lasts longer than two weeks or returns frequently). It’s also important to note that if your cat has one of these diseases, they will also likely have other symptoms of illness besides diarrhea.
What to Do About Runny Cat Poop
If your cat develops soft, runny, or watery poop, you don’t necessarily need to panic. Most cases of diarrhea in cats that come on suddenly, called acute diarrhea, are due to minor causes and will resolve on their own within a few days.
It’s reasonable to monitor your cat for two to three days if their only symptom is loose stool and they are otherwise acting fine. You could offer them a bland diet consisting of cooked boneless, skinless chicken breast or baked white fish for a few days to see if that helps. However, if you have a kitten with diarrhea, it’s best to have them looked at by your veterinarian if the diarrhea doesn’t resolve after one day. Kittens are more likely to have infectious diarrhea and their bodies are less capable of fighting off infections.
Runny Cat Poop: When to Seek Help
You should seek veterinary care if your cat’s runny poop lasts longer than two to three days, or if they develop any of the following symptoms.
If your cat has more than a couple of episodes of very liquid poop – think uncontrollable, explosive diarrhea – you should take them immediately to a veterinarian. Liquid poop contains mostly water and will very quickly lead to dehydration, which can be life-threatening.
It is normal for cats to feel a bit more tired with most causes of runny poop, but if they become extremely tired and stop walking around or moving, they are most likely seriously ill or dehydrated.
If your cat refuses to eat anything at all for more than one day, they should be checked out by your veterinarian.
A few episodes of vomiting may not be anything to worry about in a cat with runny poop. However, if your cat vomits multiple times in a day or cannot keep any food or water down, it’s important for them to receive medical care, as severe vomiting can quickly lead to dehydration and may indicate a serious issue.
In addition, if you know your cat ate a plant or toxic food, or may have gotten into a household medication, you should immediately contact your veterinarian or animal poison control for advice.
Preventing Cat Diarrhea: Tips for Healthy Poop
Feeding a complete and balanced feline diet that is appropriate for your cat or kitten’s life stage is the most important thing you can do to make sure your cat has healthy poop. Your veterinarian is your best resource for recommendations on what to feed your cat. If you do need to change your cat’s food, it’s recommended that you do so gradually over a period of at least one week, slowly reducing the proportion of the old food and increasing the proportion of the new food.
Feeding your cat cooked foods and avoiding raw food diets is also recommended to prevent your cat from getting diarrhea, as raw meat often harbors harmful bacteria such as Salmonella, Listeria, and E. coli, which can cause loose stool and more serious symptoms. You should also avoid feeding your cat table scraps, especially those containing ingredients toxic to cats or those high in fat.
If your cat is prone to having runny poop from time to time, ask your veterinarian to recommend a probiotic for them. Probiotics contain healthy gut bacteria and can improve stool quality for some cats.
Cats with food intolerances or food allergies, or those with inflammatory bowel disease, often benefit from being fed prescription diets, such as hydrolyzed protein diets or highly digestible gastrointestinal diets. If your cat has chronic diarrhea, ask your veterinarian about a prescription diet.
- “2019 Cost of Pet Care Report.” Healthy Paws Insurance, Retrieved from https://www.healthypawspetinsurance.com/content/costofcare/pet-care-costs-health-conditions_2019.pdf
- Liao, Pinfeng et al. “Abrupt Dietary Change and Gradual Dietary Transition Impact Diarrheal Symptoms, Fecal Fermentation Characteristics, Microbiota, and Metabolic Profile in Healthy Puppies.” Animals : an open access journal from MDPI vol. 13,8 1300. 11 Apr. 2023, doi:10.3390/ani13081300