A veterinarian can diagnose Giardia in dogs by performing a zinc sulfate fecal flotation test on a dog's feces, according to VCA Animal Hospitals. However, sometimes these parasites can even be seen by analyzing a direct smear of the dog's stool.
Although testing can be done to confirm if a dog has Giardia, many veterinarians can diagnose a dog based on medical history and the symptoms of the infection, states VCA Animal Hospitals. Dogs infected by Giardia exhibit foul smelling, runny, green-colored diarrhea. Some dogs also vomit frequently and are more lethargic than normal. If left untreated, these symptoms can weaken the dog and weight loss may occur over time. Although most dogs make a full recovery, this parasite can be lethal to older dogs or puppies with a compromised immune system.
Giardiasis is the term used to describe the actual infection caused by the parasite Giardia intestinales, according to VCA Animal Hospitals. Giardiasis is transmitted by consuming food or water contaminated by the cyst form of the parasite. Once the cyst is ingested, the parasite transforms into the feeding form, or trophozoite, and attaches to the intestinal wall.
Giardiasis is normally treated by a weekly regiment of an antibiotic called metronidazole, states VCA Animal Hospitals. The drug fenbendazole, an antiparasitic, is sometimes used in conjunction with metronidazole if the primary antibiotic is not effective enough on its own.