What to do and not do when you cat or kitten has diarrhea

At one time or another most cat owners will have to deal with a sick pet. One of the most common reasons cats are presented to their veterinarian is for a gastrointestinal disturbance, such as diarrhea. There are many things that can cause diarrhea in our feline patients. In outdoor cats, internal parasites or worms can be a common cause of diarrhea. With older cats, diarrhea may often be a symptom of a more serious or systemic underlying health problem.

Though many cases of diarrhea in cats is caused by something simple like a sudden diet change, sometimes your vet will need to do investigative work to find the actual cause, such as analyzing blood and stool samples, x-rays and imaging, or an ultrasound. Either way, follow this advice to help your cat get back to optimal health.


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  • know your cat’s litter box patterns
  • hold off food when symptoms are first noticed
  • simplify your cat’s diet
  • keep your cat on monthly heartworm and intestinal worm preventative
  • consult your veterinarian

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  • change foods rapidly
  • wait too long
  • forget to bring your cat’s poop sample at his annual veterinary visit
  • avoid or decline doing routine blood work in older cats
  • be afraid to change foods

Damian Battersby, DVM‘s recommendation to ExpertBeacon readers: Do

Do know your cat’s litter box patterns

Colitis, or inflammation of the large intestine is one of the most common causes of diarrhea. Colitis is typically seen with an increased frequency of defecation along with mucous and fresh, bright colored blood in or around the stool. If you are spending more and more time cleaning the litter box because your cat is passing small amounts of stool more frequently than usual, then he or she may be suffering from colitis.

Knowing your cat’s normal litter box patterns is very important in older cats, not only for increased defecation but also for the opposite—less than normal amount of poop in the box. Many older cats can suffer from constipation.

Either way it is important to know what is a normal amount of fecal material and consistency for your individual cat. This becomes more difficult with outdoor cats or in multi-cat households. But just because you don’t see your pet having diarrhea, doesn’t mean he’s not having it.

Do hold off food when symptoms are first noticed

If you notice that your cat is suffering from diarrhea and he is otherwise acting normally, the first thing you should do is hold him off food for about 12 hours. This allows everything to clear out of the gastrointestinal tract and gives the intestines a chance to rest. When withholding food, remember that this includes treats or anything else that’s edible (e.g. catnip or cat grass).

Do simplify your cat’s diet

One of the most important things you can to do in the case of gastrointestinal upset is to simplify the diet. After you have withheld food for 12 hours, start back simple with a bland, easily digestible diet, such as plain cooked chicken or egg whites. This should be fed in smaller portions than you usually feed and more frequently than usual feedings, such as 1 tablespoon every 3-4 hours. If stools return to normal, you should then slowly transition back to your cat’s normal diet. After you have him back on his regular food again, then you can start adding in the extras, like treats, one at a time.

Do keep your cat on monthly heartworm and intestinal worm preventative

If you don’t already have your cat on a monthly heartworm, intestinal worm, and flea/tick prevention, then you should start now. Monthly heartworm medication should not only prevent your cat from getting heartworm disease, but should also contain a de-wormer for common intestinal worms. This is important because one of the secondary problems associated with fleas, is that fleas can cause a tapeworm infection.

Intestinal worms are often seen in cats, and especially kittens, but are also a very common cause of diarrhea. Worms can also come from eating infected animal poop, soil or sand tracked inside on your shoes, a houseplant with potting soil, and eating or hunting infected wildlife, like rodents or squirrels. Newborns can also get worms transmitted from their mother, and all cats can get worms from swallowing fleas while grooming themselves.

It is also very important to understand that some of these parasites are zoonotic, which means that people can catch them too. This is especially important with cats because, in most cases, someone in the house is coming into contact with their feces when cleaning the litter box, and fecal material can also be spread from cat paws to counter surfaces, beds/blankets, and elsewhere when your feline friend decides to explore various places in your home.

Do consult your veterinarian

Diarrhea from simple dietary indiscretion may resolve with symptomatic treatment. If the diarrhea doesn’t resolve by holding back on food and then re-introducing a bland diet, though, then it’s time to call a professional.

Cats that have chronic soft stool or full-blown diarrhea should definitely be examined by a veterinarian, even if they are otherwise behaving normally. In these cases, there is likely an underlying problem that’s causing the diarrhea. This is especially true with middle-aged to older cats.

Underlying problems can range from simple food intolerance or intestinal parasites to more complicated diseases, such as inflammatory bowel disease; thyroid, liver, or pancreatic disease; or cancer. Some of these problems can be easily diagnosed by your veterinarian, while others require a step-by-step diagnostic approach.

Damian Battersby, DVM‘s professional advice to ExpertBeacon readers: Don't

Do not change foods rapidly

When changing your cat’s diet, always do so slowly, over a period of 1-2 weeks. With most cats, abruptly stopping one kind of food and then starting a different food will cause gastrointestinal upset, resulting in diarrhea and/or vomiting. Make sure you plan ahead before your current food runs out completely. When it does start running low, mix in a little bit of new food with each meal. Gradually increase the amount of new food you introduce each day while slowly decreasing the amount of old food over a minimum of 1-2 weeks.

Do not wait too long

Early detection greatly improves treatment success. Diarrhea, in many cases, can be a symptom of a larger underlying problem. This is especially true for indoor cats that have had no dietary change or have other clinical symptoms, such as vomiting. If the diarrhea doesn’t resolve quickly, it’s a good idea to contact your veterinarian. He or she will help to diagnosis the underlying cause and provide some relief for your kitty.

Do not forget to bring your cat’s poop sample at his annual veterinary visit

Intestinal parasite infections are common in cats, especially kittens and outdoor cats. While indoor cats are at less risk than their outdoor counterparts, indoor cats can still contract these parasites from other pets in the household or from parasites being brought into the house with house plants and potting soil or from the people in the house. Some of these intestinal parasites can also be transmitted to people. Fortunately, most of these parasites can be found through routine stool parasite examination, so next time you bring Fluffy to the veterinarian, don’t forget to bring the fecal sample!

Do not avoid or decline doing routine blood work in older cats

One of the most common causes of diarrhea and vomiting in older cats is hyperthyroidism. Hyperthyroidism is the excessive amount of thyroid hormone, and it is a very common disease in middle-aged to older cats. It can be easily diagnosed via blood work, and it is easily treatable as well.

In addition, vomiting and diarrhea may also be seen in cats with diabetes, kidney disease, and other diseases seen commonly in aging cats. Many of these problems can be diagnosed with a routine blood and urine screen, and many times, cats suffering from these diseases (especially in the early stages) may otherwise act normally, so a physical exam is not enough to diagnose the underlying problem.

Do not be afraid to change foods

Many cats suffer from dietary intolerance, and to a lesser extent food allergy. In most cases the problems are caused by the protein component in the food. Cats are carnivores so their bodies are designed to eat high protein diets, but in many cases, the protein level or the protein source may be a cause of diarrhea. You might be feeding a premium food with the best ingredients, but if your cat can’t digest beef well, and that premium food contains beef, that food is not be the best food for your pet. If your cat is suffering from chronic gastrointestinal disease—diarrhea and/or vomiting—don’t hesitate to talk to your veterinarian about diet. There are a lot of good quality foods available to feed our pets nowadays.


With all of the many causes of diarrhea in cats, it is important to speak with your veterinarian to ensure a proper treatment plan, especially in severe or chronic cases. Though commonly diarrhea can be treated with conservative or symptomatic therapy, some causes are avoidable by routinely de-worming your cat.

Don’t wait too long to take your cat to the vet as this will help to avoid serious complications that could be causing the diarrhea. By knowing the cause of the diarrhea, the symptoms to look out for, and initiating early treatment, you can help your cat get better.

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