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Giardiasis is an intestinal parasitic disease caused by the flagellated protozoa Giardia. Giardia cause disease in a wide range of animal species, including dogs, cats, and humans. Infections occur frequently in backyard ducks and other poultry.

Giardia alter epithelial permeability, leading to inflammatory response and both digestive and absorptive changes to the GI tract. Giardiasis is associated with enteritis resulting in diarrhea and reduced absorption of fat and vitamins A, B12, and E.


Giardia colonize the intestinal tract of many species, and have a direct life cycle involving an environmentally resistant cyst as the infective stage, which must be ingested. The organism is transmitted via fecal-oral route, following ingestion of food or water contaminated with feces from an infected bird.


Giardiasis is diagnosed by determining the presence of trophozoites in fecal samples or cloacal swabs by immunofluorescence.


Giardiasis is easily treated using a variety of antiprotozoal medications, including carnidazole, metronidazole, fenbendazole, and toltrazuril.


Weight loss
Mucoid diarrhea
Reduced appetite
Dry skin
Feather picking


  • History
  • Clinical signs
  • Fecal test


MethodMethod Summary
Carnidazole5-50 mg/kg PO
Metronidazole10-30 mg/kg PO q12
Fenbendazole10-50 mg/kg PO
Toltrazuril25 mg/L drinking water x 2 days, 50 mg/kg PO once, or 200-400 mg/kg feed


  • Biosecurity
  • Maintaining a clean environment
  • Keep out rodents
  • Control where dogs and cats defecate, making sure birds don't have access.


    Risk Factors

    • Vitamin A deficiency