Canine Giardia Article

So recently one our members had cause where this article I wrote some time ago for our local paper would come in handy so I decidedinsted of just mailing it to her, I'd post it for all to benefit from

Giardia, pronounced GEE-are-DYE-uh, are protozoa that live in the small intestine of dogs and cats. Giardia is found throughout the United States and in many other parts of the world. Infection with Giardia is called 'Giardiasis.' There are many unknowns about this parasite ranging from how many different species there are and which of these species affects our pets. The life cycle is unknown and veterinarians conflict on how common Giardia infections are and when they should be treated. Unlike other parasitic organisms that invade our pets, Giardia can also infect Humans and should be taken very seriously if diagnosed by your vet. It has been observed that as little as 10 cysts can cause disease in humans.

Giardias are self reproducing organisms that divide to increase their numbers and generally afflict young dogs under the age of 6 months or dogs that have an immune deficiency. Like most parasites they depend on being able to overcome the dog’s defense against infection either by its virulence or by the sheer numbers of the organism becoming established. A dog becomes infected by eating the cyst form of the parasite. In the small intestine, the cyst opens and releases an active form called a trophozoite. They attach to the intestinal wall and reproduce by dividing in two. After an unknown number of divisions, this form develops a wall around itself (encysts) and is passed in the feces. The Giardia in the feces can contaminate the environment, water, and infect other animals or people.

The most common symptom of Giardia is diarrhea. Usually infected animals will not lose their appetite, but may lose weight. The feces are often abnormal, being pale, having a bad odor, and appearing greasy. In the intestine, Giardia prevents proper absorption of nutrients, damages the intestinal lining, and interferes with digestion. Surveys have shown that about 14% of adult dogs and over 30% of dogs under 1 year of age were infected. Once passed the cysts can survive several months in cold weather, and are infective as soon as they are passed. Onset of symptoms is approximately 13 days after ingestion. Without treatment the condition may occur chronically or intermittently, for weeks or months.

Diagnosis is based on demonstration of the infection and the elimination of other possible causes of diarrhea such as Salmonella or Campylobacter. Giardia cysts may be observed directly in fecal samples or indirectly using an ELISA technique. The ELISA technique requires a kit and some method of reading a color change or production of fluorescence. Studies examining the reliability of some immunoflourescent kits have found them to be over 90% accurate, with relatively few false results, however, the tests are costly and probably only worthwhile where there are a large number of samples to be processed and a technician who is familiar with carrying out ELISAS. Direct examination of feces, using zinc sulphate centrifugal flotation, followed by staining the supernatant with Lugol's iodine, has been found to be up to 70% effective at detecting infection from a single fecal sample. The cyst output is variable so the detection rate may be improved by pooling fecal samples collected over three days. Fecal examination is the cheapest method but is time consuming and requires an experienced technician for reliable results.

There are several treatments for giardiasis although some have not been FDA-approved for that use in dogs. Fenbendazole is an anti-parasitic drug that kills some intestinal worms and can help control Giardia. It may be used alone or with metronidazole. Metronidazole can kill some types of bacteria that cause diarrhea, but it has been found to be only 60-70% effective in eliminating Giardia from dogs. It can cause liver damage and birth defects in pregnant dogs and has a very bitter taste usually resented by pets.

The easiest way to prevent Giardia from spreading is to clean and treat the affected animals, and disinfect the area with a Quaternary ammonium disinfectant used according to manufacturer's directions or a 1:5 or 1:10 solution of bleach can usually kill the cysts within twenty minutes. Allow the area to dry for several days before reintroducing the animals. Use extreme caution when using quaternary ammonium compounds and bleach solutions. Use proper ventilation, gloves, protective clothing and follow your veterinarian's recommendations. Remember, Giardia of dogs may infect people, so good personal hygiene should be used by adults when cleaning kennels or picking up the yard, and by children who may play with pets or in potentially contaminated areas.