Giardia (Giardia duodenalis)
Why it matters: Very common cause of diarrhea, especially in puppies and dogs exposed to other dogs or surface water.
How dogs get it: Drinking contaminated water, licking contaminated paws/fur, or exposure to infected feces.
Common signs: Soft stool/diarrhea (often intermittent), foul odor, gas, weight loss, or no signs.
Diagnosis: Fecal antigen testing and/or microscopic exam; sometimes additional testing is needed.
Treatment & prevention: Treatment is prescription-based and may include rechecks. Cleaning and bathing can reduce reinfection.
Human risk: Animals can spread Giardia, but people are unlikely to get Giardia from dogs/cats; good hygiene still matters.