San Juan Veterinary Hospital

2197 E Hwy 160
Pagosa Springs, CO 81147


What is Giardia?

Written by Dr. Chris Huth

Giardiasis is an intestinal disease caused by the parasite Giardia canis.  Giardiasis usually affects dogs but can occur in ther species.  Giardia has zooinotic potential, meaning it can also infect humans.  The most common way humans contract Giardia is from drinking contaminated water (ie-creek, rivers or lakes).

For most of this parasites life, it lives in the intestine of an affected animal.  The parasite forms a hard cyst that gets passed in feces and is thus spread into the environment.

Diarrhea, severe or mild, is most common sign of giardiasis.  The diarrhea can be either intermittent or chronic.  Typically there is a high volume of diarrhea with soft, almost frothy, mucous stools.  Weight loss can also occur.  The infection is diagnosed with a fecal examination or a Giardia-specific ELISA test.  Both tests can be run at San Juan Veterinary Hospital.  A positive test, in the absence of clinical signs can mean that giardiasis is likely involved, so treatment should be administered.

Drugs used to eliminate the parasite include metronidazole and fenbendazole.  The choice of drug, the dose, and the length of treatment, will depend on the severity of the infection, the reproductive status of the animal, and the size of the animal.  If the pet is severely dehydrated from he diarrhea, fluid therapy may be necessary.

Most pets don't become seriously ill because of Giardia, so the prognosis is slmost always good.  However, if a pet has some underlying disease, particularly one that compromises the immune system, giardiasis can cause a more serious infection. 

There is a vaccine on the market for Giardia, however this vaccine does not prevent infections.  The purpose of the vaccine is to reduce shedding of the cysts.  Currently, the American Animal Hospital Association guidelines list the vaccine as "not recommended".

If you have any questions regarding giardiasis, please call our office and speak to a veterinarian.