Cats can get diarrhea for lots of reasons, from food sensitivities to parasites, and even bacterial infections. Find out when to call the vet and how to help treat it at home.

By Brendan Howard
August 24, 2020
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Whether you're a first-time cat owner or someone with multiple feline friends in the house, there are few sights and smells worse than cat diarrhea. Things can get messy (and smelly!) quickly, and your litter box might not be the only place where your cat’s diarrhea ends up. Even worse, your cat’s situation can be a sign of something more serious—especially if blood shows up in your cat’s less-than-solid poop.

Get to Know Your Cat’s Poop

To know whether or not your cat’s diarrhea is the sign of something more serious, it’s important to set the standard for what should be considered her “normal” litter box habits. 

Normal cat feces is deep brown, moist enough that litter sticks to it, and doesn't feel too hard or too squishy. The smell, according to cat veterinarians at the American Association of Feline Practitioners (AAFP), "emits an odor, that while not pleasant, should not drive you from the room." While each cat is different, typically cats have bowel movements at least every 24 to 36 hours, sometimes twice a day. You know what's normal and abnormal for your cat as you scoop the litter box at least once a day and see what's there. 

Diarrhea happens when feces moves faster than normal through your cat's intestines. Water and nutrients aren't absorbed (which means your cat isn't getting the nutrition she needs), so the final result can be a watery mess. 

This wet stool may be a pile with soft-serve ice cream consistency or a pool of liquid, or somewhere in between. VCA Hospitals put together a helpful chart that illustrates the different types of cat poop, so you can get a visual understanding of the variations in consistencies. You may also see blood or mucus in your cat’s stool, and while the details are unappetizing, your cat is counting on you to notice.

If the cat kicks a lot of litter over diarrhea, you may not notice it at first. If you have a long-haired cat, you may first notice staining or soiling on fur near the anus. But once you do find cat diarrhea, it’s important to find out what’s causing this mess.

Credit: CasarsaGuru / Getty

Find Out What’s Causing Your Cat’s Diarrhea

Diarrhea is a sign of another disease or condition, not a disease itself. There are many possible causes of your cat’s diarrhea, but loose stool is usually attributed in some way with inflammation that occurs in your cat's gastrointestinal tract (from the mouth all the way to the anus). Some of the wide-ranging causes include:

  • Viruses
  • Bacteria
  • Parasites in the intestines, like Coccidia and intestinal worms
  • Conditions, like inflammatory bowel disease, colitis, pancreatic disease, cancer or hypothyroidism
  • Ingestion of toxic chemicals or poisonous plants
  • Food intolerance
  • Food allergies

With many possible causes, it can be hard to take care of a new case of feline diarrhea without talking to a veterinarian. You may be tempted to immediately try changing your cat's food without a veterinary visit. However, even if that resolves the diarrhea, the underlying causes may still be harming your cat.

When to Call the Vet 

If your cat has diarrhea for two days or more, call your veterinarian. Cat diarrhea is an emergency if the feces are black or bloody, or accompanied by other signs of illness—like fever, vomiting, lethargy or sluggishness, or lack of appetite. If those symptoms occur along with diarrhea, call your veterinarian immediately.

During an appointment, your veterinarian will ask you detailed questions about when you first noticed the diarrhea, how your cat's diet or eating has changed recently, and what your cat's stool looks like. Your veterinarian may ask you to bring a stool sample for testing (with instructions about whether your cat needs to fast or not beforehand), but also don't hesitate to take a picture of stool in the litter box (or wherever else your cat defecated). Some conditions can be aggravated by stress, so be sure to tell your veterinarian about any household changes that might have rattled your feline friend. 

Honesty is important here, even if you're a little embarrassed about the topic at hand, or how long you waited to bring the cat to the veterinarian. Renee Rucinsky, DVM, DABVP (feline specialty), who owns a cat hospital in Maryland, understands that life happens, and time goes by quickly—so don’t be shy.

"The veterinarian really needs to know how long [your cat’s diarrhea] has been going on," Rucinsky says. "Telling us that it's only been happening for a few days when it's actually been much longer can really change the way we approach the problem. We need all of the information to treat the cat appropriately."

With a detailed history in hand, your veterinarian may recommend further testing to identify viruses, bacteria, parasites, or other internal diseases that might be causing the loose stool. However, even before testing results are known, your veterinarian may recommend you hold off on feeding your cat for 24 hours or offer bland or easily digestible food.

Other recommendations might include feeding a special packaged diet or veterinary-specific probiotics. Your cat's doctor might recommend a specific dose of an extra fiber supplement (like Metamucil or canned pumpkin), but some cat’s diarrhea is helped by less fiber, not more, so check with your veterinarian on what to try and in what doses. 

Depending on the cause of your cat's diarrhea, your veterinarian may also prescribe:

  • Antidiarrheal medicine to reduce intestinal inflammation
  • Dewormer medication, if intestinal worms are the cause
  • Steroids, to control inflammation

Some cases of cat diarrhea respond quickly to medication, probiotics, or a change in diet. If you are introducing a new diet, unless your veterinarian tells you different, try mixing less and less of the old food over several days to make the adjustment less extreme for your cat's digestive system. And don't use human medicines for diarrhea without your veterinarian's supervision, as some of them contain ingredients toxic to cats. 

If you see little or no improvement in the diarrhea over a few days, if your cat isn't drinking water, or other signs of illness pop up, let your veterinarian know immediately. Over time, diarrhea can cause dehydration in a cat that's not drinking enough.

If the diarrhea continues, know that some chronic diarrhea in otherwise healthy cats can be difficult to diagnose or treat. But nutritional management over time can often lessen or eliminate even chronic bouts of diarrhea. Your cat will be happier and healthier with firmer stools, and you won't be caught cleaning up those watery poos that can sometimes miss the litter box. Everybody wins.