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  • Writer's pictureKnollwood Hospital for Pets

WHAT?! My pet has Giardia?

What is Giardia?

GIARDIA (pictured above) is one of the fastest-growing causes of pet diarrhea in our area. At Knollwood Hospital for Pets, we diagnose it multiple times a week and know what we’re telling you in this note by heart, it‘s so common!

Giardia isn’t a typical worm parasite, but a protozoan parasite. It lives and grows and swims in the bowel until it forms colonies in the bowel wall, then periodically send showers of parasite cysts outside of the body, typically with loose stool or diarrhea. Anything that comes into contact with stool (poop) from infected individuals can become contaminated with the Giardia cysts. Animals and people become infected when they swallow the cysts. It is not possible to become infected through contact with blood or urine.

How do pets and people get it?

  • Swallowing Giardia picked up from surfaces that contain traces of stool from an infected person or animal. Examples are bathroom handles, changing tables, diaper pails, or toys in people, and pet toys, kisses from your pet, and not washing hands after handling pets or after cleaning up poop outside or in litter boxes

  • Hanging out in forest preserves, dog parks and dog beaches with your pet - all tend to concentrate lots of parasites in a small area

  • Drinking water or using ice made from water sources where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)

  • Swallowing water while swimming or playing in water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams

  • Traveling to countries where giardiasis is common

  • Keeping your pet or allowing children to play in yards that stay wet, which allows the Giardia to live for a long time

  • Not picking infected stools up completely and daily or not cleaning litterboxes daily and disinfecting them regularly.

Our damp weather and relatively mild winters of the past 2 years have also contributed hugely to the current significant problem with this parasite. And, the tendency of many people to obtain pets from puppy mills, pet stores, and brokers - all of whom rarely practice good hygiene or parasite control for their breeding animals - contributes to many cases of Giardia in puppies and kittens.

How do we know a pet or person has Giardia?

Giardiasis is the most frequently diagnosed human intestinal parasitic disease in the United States and among travelers with chronic diarrhea. Pets often have Giardia, too. Signs and symptoms may range from nothing at all to any of those listed below, and can last for 1 to 2 weeks or longer .

Symptoms can come and go and can include:

  • Diarrhea

  • Gas

  • Greasy stools that tend to float

  • Stomach or abdominal cramps

  • Upset stomach or nausea/vomiting

  • Dehydration (loss of fluids)

  • Unexplained weight loss

Other, less common symptoms include itchy skin, hives, and swelling of the eye and joints. In children, puppies, and kittens, severe giardiasis might slow development, and cause malnutrition and stunting of growth.

What needs to be done for those who have Giardia?

Giardia can be treated with prescription medication, which typically must be administered several times daily for 10 day or more. It’s not unusual for treatment to have to be repeated in stubborn cases of giardiasis. Young pets may harbor the organism - and keep re-infecting themselves - for up to a YEAR.

Environmental disinfection and good personal hygiene are important to prevent accidental spread to others. Individuals with immunodeficiency, such as AIDS or cancer, or who are undergoing chemotherapy, should use extreme care, especially when handling feces or after administering medication to others.

For environmental disinfection, you can use chlorine bleach, 1-2 cups in a gallon of water (Be sure that the affected surfaces can be safely treated with bleach first). Lysol® is also reported to be effective in killing the cysts. For best results, thoroughly clean the pet's living and sleeping areas and then allow the areas to dry out for several days before reintroducing pets. And here’s something that makes our clients whose pets have Giardia especially unhappy: it’s a darn good idea to wipe a pet’s rectal area with a baby wipe after each and every BM, to prevent traces of stool from contaminating rugs, floors, bedding, and furniture. Because Giardia cysts are susceptible to drying so try to keep your environment as dry as possible.

Hygiene involves washing hands carefully after handling pets in any way and after picking up yard waste, picking up ALL stools promptly, starting that daily doggie or kitty butt-wiping routine with diaper wipes, and at least temporarily refraining from allowing "doggie kisses" until we are sure that the Giardia is gone.

In rare cases where pets are unable to clear Giardia (young pets, stressed pets, immunosuppressed pets, multi-pet households, shared yards) longer term treatment may be required and adjunct treatment with immune system support may also be indicated.

Questions? You can talk to one of our Knollwood Hospital for Pets Veterinary Technicians, via or by calling 847-891-8944 and asking for Diane or Stefanee. More info is also available through the Center for Disease Control, which takes Giardia very seriously as a public health threat:

Until next time, Dr. Mitchell and the Knollwood Hospital for Pets staff will be consoling the owners of pets who have Giardia and telling them that this, too, will pass. (That’s a veterinary joke).

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