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What is Giardia and how did my pet get exposed to it?

Giardia infection is common in dogs and cats. Giardia are one-celled parasites that invade the gastrointestinal tract and can cause vomiting and/or diarrhea. Dogs and cats may be infected subclinically and show no signs. When the eggs (cysts) are found in the stool of an animal without diarrhea, they are generally considered a transient, insignificant finding. However, in young animals and debilitated adults, they may cause severe, watery diarrhea that may be fatal. Giardia is transmitted via a fecal-oral route. An animal becomes infected with Giardia when it ingests the cyst stage of the parasite. Once inside the animal’s gastrointestinal tract, the cyst goes through several stages of maturation. Cysts are shed in the stool within 5-7 days of infection. These cysts remain in the environment and can infect other pets. Giardia is also transmitted through drinking infected water.


How is it detected?

Giardiasis or infection with Giardia is diagnosed by performing an examination of a stool sample. Various tests are used, including direct smear, fecal flotation, and fecal ELISA.


How is Giardia treated?

The typical drugs used to kill Giardia are Metronidazole (Flagyl), an antibiotic and Fenbendazole (Panacur), an anthelmintic. We commonly use both to treat giardiasis. Reinfection following treatment is thought to commonly occur, and therefore environmental disinfection is very important. Concomitant with treatment, animals should be bathed with shampoo to remove fecal debris and associated cysts. The use of diluted chlorine bleach is effective in killing the cysts found in the animal’s environment . Removing feces daily and disposing of fecal material with municipal waste also help. Post-treatment fecal examination is helpful in evaluating the success of therapy.


Can I get this from my pet?

Canine and feline strains of Giardia are not known to be infective to immunocompetent human hosts. However, people with increased susceptibility to infection due to underlying disease should consider limiting their exposure to Giardia-infected pets. Human infections are primarily acquired from other humans; transmission from dogs and cats to humans appears to be rare, if it occurs at all.

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