Giardia is a parasite (protozoa) that inhabits the small intestine of many mammals including humans. It is, in fact, the most common intestinal parasite of people in the United States. It can be very serious in puppies. In adults, most cases are not clinical (due to forming immunity), but the adult still serves as a source of infection for the pups (even if the adult has been treated). Cysts are passed in the stool and infect another animal through direct contact or contamination of drinking water. If in a cool, wet area, the cysts can survive for months. Signs in puppies include diarrhea (often with mucous), vomiting, and poor condition. Treatment includes medication (metronidazole is 65% effective, Panacur is 95% effective) and thorough bathing of dogs with removal to a clean environment (fecal contamination is a major contributor to transmission). Prevention includes thorough cleaning, disinfecting, and drying of the environment. New dogs should be checked and treated before introduction to the kennel. All contact animals should be treated.