Giardia is a single-celled parasite that lives in your dog's intestine. It infects older dogs but more frequently infects puppies. Dogs become infected when they swallow Giardia that may be present in water or other substances that have been soiled with feces.

How will Giardia affect my dog?

Many dogs infected with Giardia do not get any disease. Giardiasis, the disease caused by Giardia infection, usually results in diarrhea. Some animals with giardiasis may also throw up. Having giardiasis a long time can cause weight loss; generally poor condition; and even death, when the disease is serious.

How do I prevent my dog from getting Giardia?

The best way to prevent Giardia infection is to make sure that your dog has safe, clean drinking water. It is important not to allow dogs to drink water from areas where other animals have left their feces. Your veterinarian can perform a test on your dog's feces to see if it has giardiasis. If your dog is infected with Giardia, your veterinarian can prescribe safe, effective treatment.


To prevent spreading Giardia (and other parasites), pick up the feces left by your dog immediately and place it in the trash. Be sure to avoid contact with the feces by using gloves, a bag over your hand, or a scooping device.

Can humans be harmed by Giardia?

Giardia is a common cause of diarrhea in people, and there is a chance that Giardia from dogs could infect people and cause disease.  For this reason, if you think your dog may be infected, it is important to see your veterinarian for appropriate tests and safe, effective treatment. Infection of people with Giardia from dogs is rare. It is likely that most people become infected with Giardia passed by other people rather than Giardia from pets.