Giardia, Canine - contd.
Giardia is frequently diagnosed by means of a zinc sulfate fecal flotation examination, in which Giardia cysts and trophozoites may be identified under a microscope. If trophozoites are seen moving around on a slide smeared with a mixture of fecal material and saline solution, the canine will test positive for Giardia. However, because Giardia cysts and trophozoites are not always passed into the feces, a negative result for this examination does not rule out the possibility of Giardia. Consequently, for the diagnosis to be definitive, it is necessary for the veterinarian to periodically examine fresh fecal samples from the animal over the course of a few days.
There are other tests for the detection of Giardia although these are generally less expeditious and more expensive than a fecal flotation examination. An enzyme-linked immuno-absorbent assay, or ELISA test, may be used to detect Giardia antigens in a fecal sample but is available only in certain veterinary hospitals and specialized laboratories. A direct immunofluorescent test may be used to detect the presence of Giardia cysts in feces but also requires that a veterinarian send samples to an off-premises laboratory and await the results.
