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What is giardiasis?

Giardiasis is an infection with a one-celled protozoal organism called giardia. Giardia are not worms, but they are microscopic parasites that live within the small intestine. Despite their small size, they can be an important cause of illness, especially in puppies and kittens.

How did my dog or cat get giardia?

Giardia cysts are passed in the feces and contaminate the environment. Cysts are generally ingested after drinking from a contaminated water source, though ingestion can occur via grooming or ingestion of any contaminated material. Once inside the intestine, the cyst goes through several stages of maturation to complete its life cycle. This infection is more common in densely populated groups of animals such as a pet store or an animal shelter.

What are the clinical signs?

While these parasites can be asymptomatic in adult animals, large numbers of organisms can lead to clinical problems. Severe diarrhea, bloody feces, dehydration, vomiting, and abdominal pain can occur. While death is rare, it can occur with serious infections, especially in puppies, kittens, or ill animals.

How is giardiasis diagnosed?

Giardia are diagnosed by microscopic examination of your pet’s stool. Since your veterinarian is searching for very small organisms and shedding of these organisms can be intermittent, more than one sample may be necessary to make a diagnosis. A blood test is also available for the detection of antigens (proteins) of giardia in your pet’s blood. This test is very accurate, but is only a reliable test for dogs at this time.

How is giardiasis treated?

The most common medication is an antibiotic-type medication called metronidazole. This medication is generally given for 7-10 days, though longer therapy is occasionally required. If metronidazole is not effective in your pet, other medications are available. Re-infection is common, so environmental management is important. Prompt disposal of all feces is essential, especially in yards, playgrounds, and public parks. Litter boxes should be scooped daily and cleaned thoroughly once weekly. A mixture of dilute bleach (1:10 dilution) can be used to clean litter boxes and contaminated toys or kennels. Always wash your hands thoroughly after handling feces or cat litter.

Are giardia organisms dangerous to humans?

Giardia can infect humans, but current research indicates that dogs and cats are an unlikely reservoir for human infection. However, immuno-compromised individuals (chemotherapy patients, young children, HIV-infected individuals) should exercise caution when handling feces from a pet that has been diagnosed with giardiasis. Strict hygiene is essential.

Content prepared by St. Francis Animal and Bird Hospital, 1227 Larpenteur Ave. West, Roseville MN. 55113