Giardiasis is an intestinal upset caused by a one celled protozoa called Giardia.  It is often referred to as beaver fever since campers and other travelers get it from water contaiminated by beavers.  Giardia has two forms in its life cycle.  The first form is called a trophozoite.  This is a fairly fragile creature that attaches to the intestinal wall of a dog or human and feeds.  While one doesn’t do that much damage, multiples of them can cause diarrhea, intestinal cramping, pain, and other trouble.  Tropozoites reproduce by division and some of them enter the cyst form.  This form is the transmissible form.  It passes through the gut and goes out with the feces.  It persists in the environment for years in cyst form.  Anything that eats the feces, or drinks water contaminated by it, will ingest the cyst.  The cyst is then activated in the gut and becomes a trophozoite and starts the whole cycle over.

Both dogs and people usually pick up the cyst when drinking contaminated water.  Giardia is the cause of many “traveler’s diarrhea” experiences.  Dogs who drink from puddles or ponds, streams, or lakes, may pick up the cyst.  It is possible to have giardia and have no symptoms.  However, dogs often show acute foul smelling diarrhea with a greenish tinge to it and possibly blood in it.  The feces also have excess mucus in them.  Dogs may vomit and gradually lose weight.  The symptoms can be intermittent or continuous.  They are not generally considered life threatening unless the dog is immunocompromised or elderly, or very young.  In these cases giardia can kill a dog.

If your dog has giardia, both you and he will want it gone fast.  Your veterinarian will take a fecal smear to definitively diagnosis giardia.  It is usually treated with an antibiotic called mentronidazole in combination with an antiparasitic drug called fenbendazole.  Both are given for five to seven days to clear up the problem. Bathing the dog is also recommended to remove the cysts from the dog’s body and prevent reinfection.  Repeat fecals are usually done to make sure the giardia is dead as chronic infections can be very debilitating to the dog.  Owners must also guard against the dog becoming dehydrated from the diarrhea.

Prevention consists of keeping your dog from drinking from contaminated water.  This is not always easy, especially if you live near a pond or lake.  In addition, dogs should be discouraged from sniffing or eating other dog’s feces as they can get the cyst that way. Caution should be taken when boarding a dog as the close association with other dogs provides an ideal environment for the spread of giardia.  Make sure the dog is kept in a private space that is cleaned daily and not just released into a communal yard.

Giardia can be passed from dogs to humans, although that is rare.  Washing all surfaces with diluted bleach (one part bleach to nine parts water) and using bleach to clean up accidents can kill the cysts and eliminate the hazard to humans.