[edi]

I have had experience on humans with giardia and Flagyl(brand name)
generic name (metronidazole) has been the drug of choice indicated for that condition, the amount depends on weight.
Now, with animals I have never had that experience but alot of the same meds used with humans are also used with animals but in pediatric doses.
It is a parasite and its cureable when treated and does cause alot of diarrhea and itching in the rectum area.