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Name Giardia, Feline
Short Description
Giardia
Affected Animals: Dogs, cats, and humans. Giardia is the most
common intestinal parasite of people, transmitted most frequently
through contaminated water.
Overview:
Giardia is a parasite found in the intestines of
humans and most types of domesticated animals throughout the world,
including cats. It is also a common cause of diarrhea in cats,
especially among cats in catteries and group housing situations.
However, healthy animals rarely will experience diarrhea or other
symptoms unless they are exposed to an unusually high number of
Giardia. Young kittens and debilitated older cats, both of which
have weaker immune systems, are much more likely to show symptoms
from moderate numbers of the parasite.
Protozoan organisms, Giardia appear in two forms: as a swimming
trophozoite, or feeding form, and as a cyst that contains the
swimming trophozoites. The cysts, and not the trophozoites, are
transmitted from one cat to another when an animal becomes infected.
Clinical Signs: Clinical signs of Giardia usually only occur in
sick or debilitated adult cats or in young kittens. The diarrhea is
usually pale, malodorous, watery, and steatorrheic, or containing
fat. Some animals may lose weight but most will still have a good
appetite. Animals that have a strong immune system rarely develop
significant clinical signs of disease.
Symptoms:
See Clinical Signs.
Description:
Giardia is a protozoan parasite that can cause
intestinal infection in cats, dogs, and humans. The organism has two
main forms: a cyst form and a swimming trophozoite form. The cysts
actually contain two trophozoites, protecting them from the
environment.
The cysts, rather than the trophozoites, cause cats, dogs, and
humans to contract Giardia. Cysts are shed or passed from the
infected animal through its feces. If another animal ingests the
fecal material with the cysts in it or consumes contaminated water
or food, the cysts progress through the digestive tract into the
small intestines. Upon reaching the small intestines, the
trophozoites exit the cysts, mature, divide, and eventually go back
into cyst form. Then, they will be passed back into the feces and
out into the environment.
Some trophozoites do not go into the cyst form but get passed into
the feces. However, trophozoites cannot survive for long in the
environment and are not able to cause infection if ingested by
another animal. Cysts, on the other hand, can survive for weeks in
the soil before being ingested and infecting another animal.
Healthy cats often can tolerate Giardia without becoming ill.
Giardia is most likely to cause symptoms in cats that have a poorly
functioning immune system, in young kittens, and in catteries or
group-housed cats, where the parasites may exist in extremely high
numbers. Giardia is uncommon in healthy, older cats that receive
good care.
Diagnosis:
Often, the examining veterinarian will perform a
special fecal flotation test that is likely to damage to the cysts
or trophozoites less, or a direct fecal smear with a fresh sample of
the cat's fecal material. These tests allow Giardia cysts or
trophozoites to be identified under a microscope. A negative test
result does not mean the animal does not have Giardia, because the
Giardia cysts and trophozoites are not always passed in every bowel
movement. Repeated fresh fecal samples may need to be examined over
a period of a few days to determine the presence of Giardia.
Other tests are available for the detection of Giardia. Now
available in some areas, a test called ELISA analyses for Giardia
antigens in a fecal sample. Another type of test is a direct
immunofluorescent test that detects the presence of Giardia cysts in
feces. This test has to be sent off to a special laboratory, so
there is a delay in receiving the results.
Prognosis: Giardia is a very treatable condition and
response to treatment is rapid. Most animals recover quickly and do
not have recurrent problems. If proper prevention steps are not
taken, however, it is common for animals to become re-infected.
Transmission or Cause: Transmission occurs when the cat swallows the
Giardia cysts that are found in the feces of an infected animal, or
in contaminated food or water sources. The cysts cause infection
when swallowed by a cat.
Treatment: Treatment of Giardia involves the use of
medications such as metronidazole, which should not be given to a
pregnant animal. Fenbendazole has been shown to be very effective in
the treatment of Giardia infections in dogs, but has not been
studied in cats. However, veterinarians have had success treating
cats with fenbendazole.
Prevention: Prevention involves strict sanitation and the use
of cleaning agents proven effective in eliminating Giardia. In
catteries and group housing facilities for cats, routine
disinfection of the entire facility is critical. Cats should be
bathed often because they can carry the Giardia cysts in their
haircoat. The use of medications such as metronidazole periodically
may be very beneficial in preventing further infections.
