Giardia Infection in Dogs
Definition of Giardia
Giardiasis, sometimes called “beaver fever,” is the disease caused by infection with tiny parasites that live in the gastrointestinal (GI) tract of most mammals, including dogs and humans. These parasites are called giardia. They also infect birds. Giardia are found world-wide. Dogs become infected by ingesting contaminated water, food or feces. While infection with giardia is common, disease is not. Some dogs never show signs of discomfort, while others show mild to moderate signs of abdominal pain. Young puppies and dogs with weak immune systems can have severe reactions to the parasites, including appetite loss, diarrhea, weight loss, tiredness, dehydration, weakness, bloody or pale-colored, greasy, strong-smelling stools and sometimes death. Giardia pose a risk to immune-compromised people, including the elderly, newborns, pregnant women and people with cancer, AIDS or other serious diseases. Regular veterinary check-ups, including fecal examinations, can usually identify giardia infections. These examinations are especially important at the end of summer, after the hot season.
Giardia are found world-wide. They have what is known as a direct life cycle. Dogs become infected when they ingest the cyst (interchangeably called the “oocyst”) form of this parasite by drinking contaminated water, eating contaminated food, licking contaminated fur or otherwise coming into contact with contaminated feces in the environment. The cysts lodge in the upper part of the dog’s small intestine, called the duodenum. There, each cyst produces several motile larvae, known as
Many dogs infected with Giardia have a latent or subclinical infection, which means that they really don’t show any noticeable symptoms of illness. However, the parasites eventually damage the lining of the intestines of the animals that they infect, disrupting digestion and using up nutrients that the animals need for normal health. The effects of Giardia are most pronounced in young dogs, old dogs and those with impaired immune systems. The profuse diarrhea that frequently
The disease caused by infection with Giardia is not difficult for veterinarians to diagnose. Examination of a dog’s feces can reveal the trophozoite and/or cyst forms of the organism. Giardia can also be identified through more advanced, specialized tests. Most veterinarians evaluating a dog with diarrhea, abdominal pain and other signs of gastrointestinal upset will take a blood sample and perform a complete blood count and a serum biochemistry panel. They will also probably take
Giardia is treatable, usually on an outpatient basis. Unfortunately, the effectiveness of treatment is evaluated based on the presence or absence of cysts in the affected dog’s feces, which does not necessarily equate with whether the parasites are present inside of the dog. A dog can remain internally infected, without shedding the cyst form of the organism at the time the fecal sample is taken. In addition, infection can recur after the parasite is initially