Etiology: Giardia muris is a one-celled eukarytic organism.

Incidence: Infection with Giardia muris is rare.

Transmission: Fecal-oral transmission via ingestion of infective cysts.

Distribution: Giardia muris is found in the anterior small intestine.

Clinical signs: Clinical signs are not usually observed. These protozoa may proliferate in diarrheic states, however their role as contributors to disease is poorly defined.

Diagnosis:

Antemortem: Fecal PCR can be used. Wet mounts of fresh fecal material or use of sucrose gradient may reveal cyst forms (difficult).

Postmortem: Wet mounts of intestinal contents may reveal slow-moving flagellated protozoa with a “falling leaf” rolling motility. Histopathologic examination may also be used to diagnose Giardia species infection.

Diagnostic morphology: Broad, piriform trophozoite with 2 anterior nuclei that when stained with weak iodine solution gives the appearance of a “monkey face.” There are eight caudally directed flagella.