Giardiasis in Cats: What This Common Parasite Actually Means

In this guide

Giardia is a microscopic intestinal parasite, not a worm but a single-celled protozoan, and it is one of the more commonly diagnosed causes of persistent diarrhoea in young cats, kittens, and cats from multi-cat or shelter backgrounds. It spreads through cyst-contaminated water, food, or surfaces, and thrives particularly well in damp conditions, which makes it a genuine year-round concern given how much of India stays humid.

How it shows up

• Watery, pale, strong-smelling diarrhoea, sometimes with mucus
• Diarrhoea that comes and goes rather than staying constant
• Weight loss despite a normal or increased appetite
• A dull coat

Some infected cats show no symptoms at all and are only found to be carrying Giardia incidentally, which is part of why routine deworming and faecal checks matter even in cats that seem fine.

How it is diagnosed

A vet will usually run a faecal antigen test, which is quick and reasonably reliable, sometimes alongside a direct microscopic look at a fresh stool sample, since Giardia cysts are shed intermittently and can be missed on a single sample. Cats with ongoing symptoms but a negative first test are sometimes asked to bring a second sample a few days later.

Treatment

Fenbendazole and metronidazole are the two medications most commonly used, either alone or together for stubborn cases, typically given for five to seven days. Metronidazole needs careful dosing in cats, since too high a dose can cause neurological side effects such as wobbliness or disorientation, so never adjust the dose yourself even if a sibling cat needs a slightly different amount. A bland, easily digestible diet and, often, a course of probiotics support recovery alongside the medication.

Should you worry about catching it yourself

Giardia does have zoonotic potential in general, but the specific strains most commonly found in cats are not the same ones responsible for the majority of human cases, so the actual household risk is low. That said, good hygiene, washing hands after litter box duty, disinfecting the litter box regularly, and promptly removing faeces, is sensible practice regardless, especially in homes with young children, elderly family members, or anyone immunocompromised.

Preventing reinfection

• Wash and disinfect the litter box thoroughly during and after treatment
• Bathe long-haired cats once treatment starts, since cysts can cling to fur around the tail and hindquarters
• Treat all cats in a multi-cat household together, even those without symptoms, if advised by your vet
• Keep water bowls clean and change water daily

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