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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 chickens 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.

Clinical Signs

Weight loss
Mucoid diarrhea
Reduced appetite
Dry skin
Feather picking


  • History
  • Clinical signs
  • Fecal test

Reported Cases

  • Case 1: Giardiasis in a Stork Giardia sp. was found in the white stork in The Netherlands for the first time. The Giardia sp. trophozoites that were found in the feces of a 6-wk-old white stork, were examined by light microscopy. The parasites closely resembled Giardia ardeae that had been isolated by others from several species of wading birds belonging to the order Ciconiiformes, sharing a deeply notched adhesive disk, a single caudal flagellum, and a single round median body. Serologically, the parasites did not react with anti-Giardia intestinalis monoclonal antibodies. Although no signs of intestinal disease were observed in the stork chick, the presence of parasites in all stages of development and the huge number of parasites show that the stork chick was experiencing an active infection with G. ardeae type parasites. Ref


Carnidazole5-50 mg/kg POB Speers
Metronidazole10-30 mg/kg PO q12B Speers
Fenbendazole10-50 mg/kg POB Speers
Toltrazuril25 mg/L drinking water x 2 days, 50 mg/kg PO once, or 200-400 mg/kg feedB Speers



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

Scientific References

Risk Factors

  • Dog and cat feces
  • Rodent infestations
  • Stress

Also Consider