Giardia in Cats

Laci Schaible, DVM, MSL, CVJ
By Laci Schaible, DVM, MSL, CVJ on Oct. 20, 2021

In This Article


What Is Giardia in Cats?

Giardia is a single-celled organism classified as a protozoan. It can live in the intestines of cats (and other animals, including dogs and humans) and cause severe gastrointestinal disease. It is spread by fecal-contaminated water, food, or soil.

Giardia is found worldwide and in every part of the United States.

Symptoms of Giardia in Cats

Giardia is primarily a disease that causes a lot of severe, watery diarrhea. Giardia in cats can also cause:

You will probably notice an irritated perianal region and excessive grooming to keep clean, which is unfortunately a source of continual reinfection.

It is also worth noting that cats (and other animals) can have the protozoa present in their intestines and still not show any symptoms. It is not known how often this is the case, as Giardia is not routinely tested for in cats unless they have diarrhea.

Causes of Giardia in Cats

Giardia is a protozoan that must be orally ingested. Cats are infected by the cysts by ingesting stool or contaminated soil (via grooming) or drinking contaminated water. Contaminated food is less often a source of Giardia for indoor cats but can be a source of infection for outdoors cats.

How Vets Diagnose Giardia in Cats

Your veterinarian will gather a complete history and conduct a physical exam to evaluate your cat’s hydration status and check for intestinal pain. A quick test for Giardia is available through your veterinarian’s office. They will likely need to do a fecal test for other intestinal parasites.

Treatment for Giardia in Cats

Medications for the eradication of Giardia are readily available and affordable. Metronidazole, an antibiotic, is most often prescribed. Additional medications may be prescribed depending upon the severity of the infection and the cat’s condition.

The disease can take multiple rounds of treatment, as cats may continually reinfect themselves through frequent grooming (ingesting cysts on their fur) and other sources of environmental contamination.

Recovery and Management of Giardia in Cats

Because cats that have been treated have no “immunity” against future infection, they can easily be reinfected. Therefore, all living areas that the cats have access to should be disinfected. Ammonia, dilute bleach solution, or steam cleaning can be effective. It is the impracticality of disinfecting entire households that makes this parasite a tough one to eliminate.

If there are other pets in your household, medications may be administered to them as a preventive measure. Contaminated soil or areas can remain infective for months under the right conditions, so avoiding those areas when at all possible is advisable. 

Multiple negative tests are necessary to ensure the disease has passed, as cysts are not always shed and detected on the test. And when bringing a new pet home, it is always encouraged to have an exam and stool check for parasites as well as Giardia testing before bringing the pet home and around other animals.

Giardia in Cats FAQs

Does Giardia in cats go away?

No, Giardia is a protozoal infectious agent that will not resolve on its own. Oral medications are the recommended treatment, and Giardia does not “run its course,” as a common cold does.

Is Giardia hard to get rid of in cats?

With the appropriate medication and dosage, most cases of Giardia in cats are not hard to clear, though they do require consistent treatment, strict compliance in decontaminating the home environment, and retesting to ensure the parasite is eradicated.

How long does Giardia last?

Giardia will last until it is treated and eradicated. The environment must also be decontaminated or the pet can become reinfected.

Is Giardia contagious in cats?

Yes, Giardia is passed in the stool of infected cats. The life cycle is fecal-oral, which means another cat would have to ingest the cysts from the environment. Keep in mind that cats are fastidious groomers, so you can imagine how the disease is spread easily.

Can my cat give me Giardia?

Yes. Giardia can cause diarrhea and disease in humans. If your cat is diagnosed with Giardiasis, environmental disinfection is important for your own health and safety, as well as preventing recurrence in your cat and any other pets.

Is Giardia painful for cats?

Yes. Cramping and diarrhea are as painful for cats as they are for humans.

Is Giardia fatal in cats?

If untreated, Giardia can be fatal, especially in kittens. Its dehydrating effects can be quite severe.

What happens if Giardia goes untreated in cats?

Cats can have painful cramping and diarrhea as well as dehydration and other symptoms if Giardia is not treated. In kittens or smaller cats, Giardia can cause death from dehydration.

Laci Schaible, DVM, MSL, CVJ


Laci Schaible, DVM, MSL, CVJ


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