Diarrhea in Dogs and Cats – All You Need to Know About Causes, Treatment, and Prevention

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Healthy dogs and cats should normally produce firm stools that are well-formed and are brown in color. A dog or cat that is suffering from diarrhea will produce feces that are soft, or sometimes even liquid in consistency. There may also be a change in color from that which is normal for your pet, or your pet may pass diarrhea with mucous or diarrhea with blood in it.

Diarrhea is very common in both dogs and cats and has a huge number of different causes. We’re going to take a look at why diarrhea occurs, and what you as a pet parent can do to prevent it.

What is ‘acute’ and ‘chronic’ diarrhea?

Veterinarians classify diarrhea as either acute, which means a single episode in isolation, or chronic, which refers to a protracted episode that lasts longer than 3 weeks. Chronic diarrhea can also refer to several episodes which occur close together, even if feces are normal in between these episodes.

Usually, acute diarrhea is more common in young animals – either puppies and kittens or young adult animals. Chronic diarrhea, on the other hand, occurs more frequently in older dogs and cats. That being said, acute or chronic diarrhea can be seen in pets of all ages.

What happens if my pet has diarrhea?

Most episodes of diarrhea occur suddenly and usually only last a few days. They often either resolve on their own or with a short course of treatment. Dog and cats normally remain bright and well in themselves, unless their diarrhea is severe or doesn’t improve after a few days. Young and elderly pets are more susceptible to becoming poorly very quickly if they suffer from diarrhea, so it is important to contact your veterinarian for advice if your pet is very young or old.


If the diarrhea is severe, your pet can rapidly become dehydrated. Pets may also suffer from vomiting, loss of appetite, or blood in their feces. All of these factors may also contribute to loss of fluid from the body, so it is important to recognize the symptoms of dehydration in your pet.

If your pet becomes dehydrated, they need urgent treatment. Signs of dehydration include:

  • Sunken eyes
  • Pale, ‘tacky’ or sticky gums
  • Sleepiness or lack of energy
  • Loss of appetite.
  • Loss of skin elasticity

Dehydration can be very serious so if your pet is showing any of these signs then you should contact your veterinarian straight away for further advice and treatment.

Causes of diarrhea

There are a huge number of different causes of diarrhea in dogs and cats but some of the more common causes are listed here:


The most common cause of diarrhea in dogs and cats is a sudden change of diet or the consumption of inappropriate food. This type of diarrhea will usually resolve on its own after just a few days. Sometimes, a dietary intolerance may result in diarrhea. In these cases, the diarrhea will not resolve until that food is eliminated from the diet.

Parasitic Infections

It is common for dogs and cats to have worms or other parasites, especially if they hunt or scavenge dead animals when out and about. Puppies and kittens are more likely to carry a high worm burden, and therefore more likely to suffer from parasite-associated diarrhea, but parasites can cause diarrhea in dogs and cats of all ages. Your veterinarian will perform regular examinations of your pet’s feces to decide on the best parasite treatment for them.

Fecal testing

There are several different parasites that may infect your pet’s digestive tract including roundworms, hookworms, whipworms, giardia, coccidia, and liver flukes. Your veterinarian can look for these parasites in your pet’s feces by performing various different tests and then examining the feces under a microscope. Some of the most common fecal tests are:

  • Fecal smear – This involves taking a tiny amount of feces, smearing it onto a slide, and then examining the slide under a microscope to search for parasites. This is the simplest of tests but is usually only used in addition to another test or if a heavy parasite burden is suspected, as parasites in low numbers can easily be missed.
  • Fecal float – This test is routinely performed by veterinarians and involves mixing a small amount of feces with a special solution that results in parasite eggs floating to the surface. These eggs can then be collected using a glass slide and this is examined under the microscope. As a general rule, the greater the number of eggs seen, the heavier the worm burden of your pet, but this isn’t always the case. Puppies and kittens will normally have a fecal flotation performed at every initial veterinary visit to monitor the response to parasite treatment. For adult dogs and cats, a yearly fecal flotation is usually performed at their annual visit, although more frequent fecal floats may be required if they are suffering from diarrhea or if they are losing weight.
  • Centrifugation – This test is less commonly used because it is more expensive but it is more effective at detecting parasite eggs than some of the other fecal tests. It involves mixing feces with a special liquid and then spinning this solution at a very high speed in a centrifuge to separate out the eggs.

Bacterial infections

Sometimes, dogs and cats with diarrhea may have bacteria such as salmonella or campylobacter in their feces. These infections can be diagnosed by testing the feces of your pet. It can sometimes be difficult to know whether or not these bacteria are contributing to the cause of your pet’s diarrhea as many healthy dogs and cats can also shed these bacteria in their feces.

Some bacterial infections can be zoonoses. This means that they can also infect humans! Practicing good hygiene by washing your hands after contact with your pet is essential. This is especially important for young children, the elderly, and the immunosuppressed.

Viral infections

Viral infections are a less common but potentially very serious cause of diarrhea in dogs and cats, particularly puppies and kittens. Infections such as parvovirus or panleukopenia can cause severe and sometimes deadly disease. Proper vaccination can prevent these diseases.

Diseases of the digestive tract

These are more common in adult dogs and cats and include diseases such as Inflammatory Bowel Disease (IBD) or neoplasia (cancer) of the digestive system. These diseases can affect the absorption of nutrients from your pet’s digestive tract which can result in diarrhea. Your veterinarian may suggest additional tests such as blood tests, x-rays, or ultrasound if they suspect your pet has a disease of his digestive tract.

Treatment of diarrhea in dogs and cats

Treatment of diarrhea may differ depending on the cause.

Diet change and a ‘bland diet’

Veterinarians often recommend feeding a highly digestible intestinal diet with a reduced fat content until the diarrhea has resolved. There are commercially available prescription diets that you can obtain from our team – these are the best option, as they’re nutritionally complete.

Alternatively, you could choose to feed a homecooked diet. Homecooked diets of boiled chicken and rice for dogs (or boiled chicken or white fish for cats) are suitable for feeding for a few days until your pet is better. However, they are deficient in nutrients and are not suitable for feeding for more than a couple of days.

Probiotics and prebiotics

Probiotics and prebiotics may also help to aid your pet’s recovery from diarrhea. Probiotics are the ‘good bacteria’ that live in the digestive tract and prebiotics are a source of food for these live bacteria which helps them to multiply.

Products containing probiotics and/or prebiotics may also contain natural binders which can help your pet to produce firmer stools. One of our team can recommend a suitable product for your pet.


Antibiotics are rarely required to treat diarrhea in dogs and cats and can sometimes even make diarrhea worse. This is because antibiotics destroy the good bacteria in your pet’s gut, along with any bad bacteria. Generally, antibiotics will only be prescribed in cases where pets are very ill.

Home remedies for diarrhea

  • Fresh water: It is important to ensure that your cat or dog has plenty of fresh water available so that he can replace the fluid he is losing in his diarrhea.
  • Rest: Allow him to rest if he needs to and make sure he has somewhere quiet that he won’t be disturbed.
  • Toilet breaks: If you have a dog with diarrhea then be sure to give him plenty of opportunities to go outside and toilet as he may need to go more frequently than usual. For cats with diarrhea, it may be sensible to provide him with a litter tray, even if he normally toilets outside. Never punish your dog or cat for having accidents in the house as sometimes they are unavoidable, and your pet will not understand why they are being punished.

Prevention of diarrhea

One of the main things you can do to prevent any unwanted diarrhea in your pet is to stop them from scavenging inappropriate food items and do not feed them too many treats, particularly human food.

If you wish to change their regular diet, then do so slowly and gradually by feeding increasing amounts of the new food and decreasing amounts of the old food, over 7 days – more if your pet is known to be sensitive. It is also important to ensure your pet has regular fecal tests and is up to date with parasite treatment as recommended by your veterinarian.

If your pet has a particularly sensitive digestive system and is prone to tummy upsets, then keep his diet as consistent as possible. It might be beneficial to feed a specially formulated food that is easily digestible. One of our vets would be happy to advise you on the best option for your pet.


Diarrhea in dogs and cats is very common and a short-lived, isolated episode may be nothing to worry about. In these cases, you can often aid your pet’s recovery by feeding him small meals of bland food for a few days and ensure he drinks plenty of water.

However, if your pet has diarrhea that isn’t resolving, or he seems unwell in any way, or he is dehydrated, then it is important to book an appointment with us straight away to get him checked over.

FAQs about diarrhea in dogs and cats

What should I feed my dog/cat with diarrhea?

Our team can recommend a highly-digestible commercial diet specially formulated for diarrhea. However, you can choose to feed a homecooked diet of boiled chicken or white fish. Feed this on its own for cats and mixed with boiled rice for dogs. Please note that this is not fully balanced and is deficient in nutrients, so is not suitable for feeding for more than a couple of days.

How long will a dog or cat have diarrhea after changing food?

Your dog or cat may have diarrhea for a couple of days if they have had a sudden change of food. If your pet’s diarrhea is not better or improving after this time then contact your veterinarian for further advice.

When should I call the vet if my dog or cat is having diarrhea?

You should contact your veterinarian right away if your pet has diarrhea and is also showing signs of dehydration or has other symptoms such as vomiting. Contact your veterinarian if your pet has had diarrhea for a few days that is not improving, or if he seems unwell in any way.

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