When Harry Met Giardia
Monday, June 8, 2009
By: Amarpreet Kaur, DVM

Just what is Giardia...

Harry is a curious and energetic Shiba Inu.  With the exception of some busy weekends, he accompanies his owner to the park for a daily stroll.  While there, he has many adventures visiting with his canine friends and exploring all the puddles.  One day while on their routine outing, Harry’s owner noticed that his beloved canine had very loose stool.

At first, the symptom was intermittent.  But when the loose stools persisted for more than a week, Harry and his owner took a trip to the family veterinarian.  Medical testing determined that Harry had met Giardia (probably in one of those puddles at the park) and was now suffering from Giardiasis.


Giardia lamblia are protozoan (a one-celled organism) parasites that live in the intestines of various animals including humans and pets.  Surveys of various canine populations report a presence of Giardia as follows:  a) 10% prevalence in dogs that receive proper care. b) 50% prevalence in puppies. c) 100% prevalence is possible in breeding kennels.  Young animals and individuals with weakened immune systems are more susceptible to infection.  Giardia is not as common in cats but can be found in felines less than 3 years of age.  


A high prevalence factor combined with the ability of Giardia cysts to survive for longer periods of time in environment are the primary causes of new Giardiasis infections.  Giardia is simplistic in structure, adapts to perform basic functions, multiplies in the animal, and can survive outside the host and within the environment for extended periods of time. 


Giardia lives in the intestine by surviving on the host’s nutrients.  Although they do not have the structure of normal cells, they have evolved to swim around using thin, long whip-like structures called “flagellae”.  They have discs through which they suck and hold on to the intestinal wall.  They multiply by fission (dividing) under favorable conditions.  They round up to form cysts and are shed in the feces of the host. 


The cysts are resistant to the harsher conditions found outside the body and can remain infectious for months in cool, damp areas.  They accumulate in both indoor and outdoor environments that are susceptible to high levels of moisture such as kennels and standing pools of water.  When animals ingest these cysts through contaminated water or food, they are broken in the stomach and release trophozoites, which populate the animal’s intestines and continue the life cycle.


Giardiasis causes problems with normal intestinal function, which leads to diarrhea and an inability to properly absorb nutrients.  After infection occurs, it takes 5-16 days for the trophozoites and cysts to be found in the feces even though diarrhea can precede the shedding of Giardia.  Depending on the severity of infection, diarrhea can vary from being self-limiting, intermittent or continuous in nature.


Fortunately, most pets do not become seriously ill from Giardiasis.  Detecting the Giardia trophozoites or cysts in the feces using the ELISA technique or through the use of microscopy makes diagnosis quite simple.  There are many drugs effective in treating Giardiasis.  These are available as prescribed by a licensed veterinarian after diagnosis has been made.


Recurring infections are prevented keeping the animal’s environment clean and dry.  Fecal waste should be removed daily.  Common household disinfectants like Lysol can be used as part of the cleaning protocol.  Surfaces should be allowed to dry thoroughly after cleaning.  Animals who have been diagnosed with the illness should be bathed in order to remove any fecal debris and associated cysts.  Additional preventative measures include keeping pets from drinking or playing in stagnant water sources. 


So, upon diagnosis, Harry also underwent a treatment protocol prescribed by his veterinarian.  His living quarters, pet bedding and yard were thoroughly cleaned.  And he received his monthly bath a little early. As expected, Harry made a full recovery and was back to his routine strolls in the park in no time at all!