Giardia Heartworm
What kind How do dogs get Giardia?
Giardia is transmitted from host to host by ingesting cysts in
contaminated feed or drinking water. Cysts may also be found in streams or
other water sources.
The trophozoite stage may also be infective to dogs. This stage
does not survive for very long after being voided in the feces. Therefore, it
probably does not contribute significantly to the transmission of Giardia.
Giardia can infect humans. The clinical signs are similar to those reported for dogs. We do not know the significance companion animals serve as a source of infection for humans. Until it has been proven otherwise, we should assume that Giardia can be transmitted from one animal to another and from other animals to humans.
What harm does Giardia do to dogs?
The significance of Giardia in dogs is still not certain. Although Giardia
has been reported from dogs with diarrhea and dysentery, it has also been
reported in apparently healthy dogs.
Clinical signs usually occur in dogs less than one year of age. But giardiasis may also occur in older dogs, or in animals suffering from other diseases or those undergoing chemotherapy.
Figure 1. Giardia
spp. as seen in a fecal smear.
How can I know when a dog has Giardia?
Clinical signs range from none in asymptomatic carriers, to mild
recurring diarrhea consisting of soft, light-colored stools to acute explosive
diarrhea in severe cases.
Other signs associated with giardiasis are weight loss,
listlessness, mucus in the stool and anorexia. These signs are also associated
with other diseases of the intestinal tract and are not specific to giardiasis.
How can I be sure a dog has Giardia?
Diagnosis is confirmed by finding the cysts or motile stages in
feces. A negative report does not rule out Giardia.
Because cysts are only passed periodically, several fecal examinations may be necessary to diagnoses this parasite. At least three fecal samples, examined over a period of seven to ten days, should be examined.
How do you treat a dog for Giardia?
There are two antiprotozoal drugs commonly recommended (metronidazole
and quinacrine). Contact your veterinarian for the drug of choice and treatment
program. All infected animals should be treated whether or not they show
clinical signs.
Figure 2. Scanning electron micrograph of Giardia attached to the inner
surface of the intestine.