Giardia duodenalis [gē-AHR-dē-ah doo-ō-dǐ-NӐ-luhs] is an intestinal parasite that can affect lots of animals — including dogs — and people too. It can also spread from animals to humans. Infection with this parasite — known as giardiasis [gē-ahr-DĪ-ah-sus] — often causes diarrhea, which is sometimes severe.

Metronidazole is the drug of choice for giardiasis, but traditionally, veterinarians only had the option of using a human formulation. However, the Food and Drug Administration recently approved an oral version of the drug to treat Giardia infections in dogs.

The medication is only available by prescription from a veterinarian and comes with label recommendations for safe handling. Ask your veterinarian for more information if the need arises.