Meatball tested positive on his blood work for giardia. However, his stool samples showed no signs of it. My vet said if they don't see signs of it in the stool, and the dog is eating, no diarrhea, he doesn't treat it. He just told me to keep a eye on him and told me what to look for. Meatball eats tons of rabbit poo. It's unavoidable, my neighborhood yards are full of it. So, that is my experience with it. Sorry I couldn't be more hhelpful.