What is Giardia?

Giardia is sometimes confused with worms because the organism(s) invade the gastrointestinal tract and can cause diarrhea.  It is not a worm, but instead a unequaled organism that is a parasite and is classified as a protozoan.

How does my pet get Giardia?

Giardia lives in many different and unexpected water sources.  Such sources include, but are not limited to, flood waters, muddy creeks, waste water, well water, mountain streams, ponds, lakes, backyard pools and even city water systems.  Giardia is easily eliminated with the proper filtration system in water supplies.  However, the filtration systems can fail, especially after heavy rains, thus causing breakouts of giardia infections.

Is my pet at risk for getting Giardia?

Animals at higher risks of acquiring Giardia are : outdoor dogs and cats, hunting dogs, farm dogs and cats, city dogs and cats, kenneled dogs, adopted strays, and animals that swim in ponds, lakes or streams or that drink water from any of the above water sources.  Birds, reptiles, ferrets and amphibians can also get giardia.  Pets considered at increased risk for more serious signs associated with giardia are puppies, kittens, pets with compromised immune systems.

How is Giardia infection diagnosed?

Having Giardia is called Giardiasis.  Giardiasis is diagnosed by performing a microscopic examination on a small amount of fresh stool.  The giardia cysts are very small and usually require a special flotation medium for detection.  The cysts are only shed intermittently, thus one negative sample does not rule out infection.  So you can see why it can be difficult to diagnose.  Sometime, four or five different stool samples need to be checked.  There is also a blood test that can be run to check for Giardia antigen in the bloodstream.  This test is considered to be difficult to interpret and is not the primary method for detecting giardia.  However, the test can come in useful for some cases, so talk to your veterinarian about the test.  Occasionally, the organisms can be seen on a direct smear of the feces on a glass slide.

How is Giardiasis treated?

The drug commonly used to treat Giardia is metronidazole.  Metronidazole is an antibiotic but is also effective again Giardia which is not a bacterium.  The drug is given for 8 days.  Just with any medication, there could be possible side effects.  The possible side effects for metronidazole are: anorexia, nausea, vomiting, diarrhea, lethargy, weakness, and ataxia (uncoordinated walking).  If you see any of these signs, stop the medication and call your veterinarian immediately.  These side effects are rare, but can occur.  Some veterinarians will use a drug called Panacur to treat giardia.  Please discuss treatment with your veterinarian.  There is no medication that is 100% effective at getting rid of all the giardia organisms in the intestinal tract.  The medication is to reduce the number of organisms in the intestinal tract so that the animal no longer has diarrhea.  We recommend brining in another stool sample at the end of the treatment period to see if any giardia organisms are seen.  If some giardia is seen under the microscope, but the animal has normal stool after treatment, most veterinarians will not retreat the animal.  The goal of treatment is to stop the diarrhea associated with giardiasis.

Can pet owners become infected with Giardia?

Giardia can also cause diarrhea in humans.  The most likely source of human infection is from recreational water use such as swimming and wading pools.  However, one can get giardia from your pet.  Giardia is passed through a fecal-oral route.  The organism is shed in the stool and thus into the environment.  One must ingest the giardia cysts to become infected with giardia.  If you don't wash your hands after picking up stool after your pet or after handling your pet, you could potentially become infected with giardia if your pet has giardia.  Children and people with compromised immune systems are at higher risk of infection.  If you just remember to wash your hands, you should be fine.

Can my other animals become infected?

We recommend checking a stool sample from each pet in your household if one pet has been diagnosed with giardia.  Many animals have giardia in normal stool samples.  There are debates between veterinarians as to whether we should treat animals that have giardia in their stool sample but have normal formed stool.  Some veterinarians will not treat an animal if the stool is normal.  Some veterinarians will.  There has been no concrete evidence that if you treat an animal with giardia that you will get rid of the every single organism in the intestinal tract.  Thus, if you treat an animal with normal stool but that has a few giardia organisms, are you doing that animal a favor?  We just don't know.  Please discuss everything with your veterinarian.

How is Giardiasis prevented?

Decontaminate the yard by picking up stool every time the pet eliminates (or clean the litter box several times a day).  Avoid, if possible, exposure to free running water, lakes or streams.  You could clean surfaces with dilute chlorine bleach (one cup bleach per one gallon of water) if needed.  You should always wash your hands after handling your pet and when done cleaning up after your pet.  There is a giardia vaccine for dogs.  The vaccine does not prevent the dog from getting giardia.  However, it does lesson the physical signs (vomiting, diarrhea) and helps reduce the amount of giardia cysts shed in the stool into the environment.  Speak to your veterinarian for more information and to see if your dog should receive the vaccines.  It is currently only licensed for use in dogs.  Dogs need 2 giardia vaccines, 3 weeks apart, before it becomes a yearly vaccine.

My pet has been treated for Giardia, but still has diarrhea, what now?

Again, no one medication is 100% effective for every single pet.  Sometimes another stool sample should be checked to look for other causes.  Your veterinarian will let you know the best course of action to take.  Some pets just need more frequent treatments or a different medication.