Giardia is a single-celled protozoan parasite that can live in the intestinal tract of humans and animals.  It can cause illness such as diarrhea, vomiting, and fever and infection is referred to as giardiasis.  However, many dogs infected with Giardia are subclinical and do not have diarrhea or any signs of infection. 

How does my pet get giardia?

Giardia lives in the intestines of infected animals and will intermittently shed cysts into the feces.  These cysts are able to live for weeks in the environment and can cause illness when accidentally ingested.   Domestic animals can become infected when drinking contaminated water or when exposed to infected fecal material on the haircoat or in the environment.  Animals have a higher chance of getting sick when living in overcrowded or unsanitary conditions. 

How is it diagnosed?

A routine fecal exam can sometimes identify cysts in a fecal sample.  However, the organisms do not always shed the cysts and the cysts are very small and difficult to see.  Therefore, a negative fecal exam does not rule out infection.  A fecal exam is often accompanied by another test that detects giardia antigens, and is a more accurate indication of exposure.

How is my pet treated?

The goal of treatment is to eliminate clinical signs and shedding of infective cysts.  There are several deworming and antibiotic medications available that can be safely used in dogs and cats.  Most therapies require anywhere from 3-7 days of treatment and sometimes require follow-up treatment and testing. 

The prognosis for recovery is good in most animals, and clinical signs usually resolve.  Some animals can have recurrent clinical signs due to a persistent infection or due to coprophagia (eating feces). 

Is my family at risk of getting infected?

Giardia is zoonotic, and can potentially pass from dogs to humans.  Families with infected dogs should practice good personal hygiene.  Immunodeficient adults and children are at a higher risk and should use care.  Hard surfaces can be cleaned with quaternary ammonium compound products or bleach mixed with water (3/4 cup of bleach for 1 gallon of water).  Carpets can be steam cleaned at 158°F for 5 minutes, or 212°F for 1 minute.  Giardia cysts are susceptible to heat and drying, so be sure to keep the environment as dry as possible. 



Centers for Disease Control and Prevention.  “Parasites – Giardia.”  CDC, 8 March 2011.  Web.  31 December 2014. 

Côté, Etienne. Clinical Veterinary Advisor. St. Louis: Elsevier Mosby, 2011.  Print.

Ward, Ernest. Giardia in Dogs.  Lifelearn Inc, 2011.