Giardiasis (Giardia Parasite Infection)

Giardiasis (commonly known as Giardia) is a common gastrointestinal infection caused by a microscopic, single-celled parasite (protozoan) called Giardia duodenalis. Pets contract Giardia by drinking contaminated water from puddles, streams, or dog park communal bowls, or by ingesting microscopic cysts from infected feces. Once inside the small intestine, the parasites multiply and attach to the intestinal wall, damaging the microscopic villi that absorb nutrients and water. This leads to the hallmark symptom: soft, pale, watery, or greasy diarrhea that often smells unusually foul and contains visible mucus. Giardia is notoriously stubborn and prone to reinfection.