Giardia is a relatively common protozoal parasite that can cause diarrhea in people and dogs (among other species). It can also be present in healthy pets, with most studies reporting Giardia shedding in approximately 7% of healthy dogs. While recent research indicates that a large percentage of dogs with Giardia carry types that do not infect people, this parasite is still a concern, particularly in households high-risk households with immunocompromised individuals, very young children and elderly persons.

What do I do if I’m in a high-risk household and my dog is diagnosed with Giardia?

  • Genotyping of Giardia from the dog to see if it is a strain that affects humans would be ideal, but this is not readily available outside research labs. Maybe in the future this will become a standard test.
  • The dog should be treated according to your veterinarian’s instructions. The entire treatment course must be completed.
  • All other dogs and cats in the house should be treated at the same time, even if they have been tested and were negative, because we want to avoid "cycling" of Giardia between the pets.
  • All animals should be bathed on the first and last day of treatment to reduce the risk of re-infection from Giardia cysts on the fur. This should not be performed by high-risk individuals, and is probably best done at a veterinary clinic or groomer to reduce bathroom contamination, if bathing can’t be done outside.
  • All animals should be tested after treatment to ensure the infection has been eliminated. This is usually done about 5 days after the last treatment. If antigen testing is used, some animals will still have positive results 5 days after treatment because of dead Giardia still working their way out, in which case re-testing at around day 21 post-tretament is recommended.
  • Care should be taken to avoid direct and indirect contact with feces. Close attention to handwashing promptly after cleaning up feces or fecal-contaminated areas is very important. Regular handwashing after contact with pets is always important.