Giardia spp. as seen in a fecal smear
Figure 1. Giardia spp. as seen in a fecal smear.

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.

Can people get Giardia from dogs?

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.

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. $0$0Because 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.

Scanning electron micrograph of Giardia attached to the inner surface of the intestine.

Figure 2. Scanning electron micrograph of Giardia attached to the
inner surface of the intestine.


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