Cats catch Giardia by swallowing microscopic cysts shed in an infected animal’s feces. A shared litter area, contaminated surfaces or water, and grooming after contact with contaminated material can all create exposure. Cats do not need to fight or touch noses for transmission to occur.
An infected cat may look healthy and still shed Giardia. In a multi-cat home, remove feces daily, clean contaminated items, and ask your veterinarian how to manage the infected cat and any housemates.
How does Giardia spread between cats?
Giardia spreads through the fecal–oral route: a cat becomes infected after swallowing cysts that originated in infected feces. These cysts can persist outside the host long enough to contaminate a litter area, surface, or water. A cat may then ingest them while exploring or grooming after contact with contaminated material. The CDC describes this sequence as contact with a contaminated surface, such as a dirty litter box, followed by licking the body (CDC, “About Giardia and Pets,” 2024).
Cornell University’s College of Veterinary Medicine identifies cysts in another infected animal’s feces—often a littermate or a cat that carries the parasite—as the route of infection in cats. Its guidance says giardiasis is more common in multiple-cat households and catteries, where there are more opportunities for fecal contamination to reach another cat (Cornell Feline Health Center, “Gastrointestinal Parasites of Cats,” updated June 2018).
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Direct contact is not required: contaminated material must be swallowed. Giardia is not spread through the air. Sharing a food bowl or nose-to-nose contact is not, by itself, the mechanism described in veterinary guidance; the concern is fecal contamination reaching a cat’s mouth.
Can my other cat catch Giardia?
Yes. If one cat is shedding cysts, another can be exposed by encountering contaminated litter, surfaces, water, or items and then swallowing the cysts. A cat can also be infected without obvious symptoms, so a housemate that appears well is not necessarily uninfected. Cornell notes that most Giardia-infected cats show no signs, yet may remain a source of infection to other cats.
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Tell your veterinarian that other cats live in the home. The CDC recommends sharing this information so the veterinarian can advise on whether housemates should be assessed or managed (CDC, “About Giardia and Pets,” 2024). Do not assume every cat needs the same testing or treatment; that decision depends on veterinary assessment.
Can a cat have Giardia without symptoms?
Yes. Many infected cats have no obvious illness. Others may develop acute or chronic diarrhea. The Companion Animal Parasite Council (CAPC) describes affected feces as potentially pale, malodorous, mucoid, or fatty, but stool appearance alone cannot confirm Giardia (CAPC, “Giardia,” guideline page updated August 3, 2026).
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Estimates vary by the cats counted and how samples were collected, so they are not interchangeable. Cornell’s 2018 feline parasite page gives a general estimate of less than 5% of cats, while cautioning that rates can be much higher in some environments. CAPC’s 2026 guideline page reports Giardia in 4.82% of fecal samples submitted to commercial laboratories in a nationwide 2023 U.S. survey; that is a submitted-sample figure, not an estimate for all U.S. cats. CAPC also reports an average of 10.3% among U.S. cats with clinical signs, a different group that should not be compared directly with the other figures.
What should I do if I think my cat has Giardia?
Contact a veterinarian rather than trying to diagnose or treat Giardia at home. Diarrhea has many possible causes, and symptoms alone do not establish that Giardia is responsible. A veterinarian can assess the cat and choose appropriate fecal testing. CAPC discusses diagnostic methods and recommends veterinary-directed treatment; it also notes that no drugs are approved for treating giardiasis in cats in the United States and that evidence is limited for some clinical situations.
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Give the veterinarian details about symptoms, when they began, and whether other cats share the home. Follow the veterinarian’s advice about testing, treatment, and follow-up; do not use medication or dosing intended for another animal or source as a home remedy.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do I clean my house after my cat has Giardia?
Focus on removing feces promptly and cleaning items and surfaces that may have been contaminated. Cleaning reduces opportunities for exposure and reinfection, but outdoor areas such as soil, grass, and standing water are difficult to decontaminate.
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Litter and feces
- Scoop and dispose of feces every day. CAPC recommends daily feces removal; Cornell also advises daily litter-box feces removal and regular cleaning.
- Clean the litter tray regularly, especially if feces have contaminated it. Wash your hands after handling litter or cleaning the box.
Pet items and surfaces
- During treatment, clean and disinfect the infected cat’s items daily if possible. The CDC specifically includes items such as toys, bowls, and beds in this advice.
- For contaminated surfaces, CAPC identifies steam-cleaning or commercially available disinfectants as options, followed by thorough drying. Check the product label for the surface and intended use, and keep pets away as directed. Do not assume that every cleaner or disinfectant kills Giardia cysts.
Outdoor areas
CAPC notes that soil, grass, and standing water are difficult to decontaminate. Prioritize preventing access to visible fecal contamination and ask your veterinarian for advice suited to your yard and household.
Can people catch Giardia from cats?
The risk from cats appears limited or uncertain in the cited guidance, rather than impossible. Cornell says most human giardiasis cases do not result from cats, while noting uncertainty about whether feline Giardia species can infect people and that some studies suggest this may be possible. CAPC says human infection from a dog or cat source has not been conclusively demonstrated in North America. Because the risk is not framed identically by these sources, use sensible hygiene: wash your hands after handling cats, litter, or feces, and handle waste carefully.
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