Giardiais a protozoan parasite that can infect the gastrointestinal tract of dogs and is capable of causing diarrhea, vomiting, weight loss and lethargy — although many infected animals show no signs at all. It is common throughout the United States and can cause infections at almost any time of year. Unlike many other infectious organisms, giardia persists longer in the environment when conditions are cool and moist. Most dogs become infected by drinking water contaminated with feces. Giardia then infects the small intestine, and infected dogs pass microscopic cysts in their stool. These cysts can then infect another animal or person if ingested. Giardia cysts are very resistant in the environment, and can live for many months under the correct circumstances. These cysts are a threat to pet health, and giardia is a very common cause of pet diarrhea in the United States.
All dogs — even those on year-round parasite preventives and those without diarrhea — should have at least one to two fecal samples performed annually as part of their wellness exam to screen for gastrointestinal parasites, including giardia.
All dogs with symptoms of vomiting or diarrhea should be tested for giardia and other gastrointestinal parasites.
All newly adopted dogs should be tested for these parasites before they are introduced to a new home, and all dogs returning from high-risk environments (e.g., kennels, dog shows, boarding facilities, etc.) should be tested.