Nope, thank goodness I've never had giardia. But we have encountered it in young puppies. And it CAN kill them. Diarrhea was the most obvious symptom. Had one or two adult dogs that got giardia too. Again diarrhea - and severe weight loss. Can be difficult to find in stool samples. Doggone things look like monkey smiley faces under the microscope when you can find them. Easily treated - w/flagyl if I remember correctly. Or sulfa. Its been so many years now I'm not sure that I remember which med we used to treat with.
My computer says I need to upgrade my brain to be compatible with its new software.