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Published: Jun 29, 2012

Giardia refers to a single-celled parasitic species of protozoa that attaches itself to the intestinal wall of many animals, including dogs, cats and even humans. Giardia is typically found in contaminated water. Anybody who has gone overseas and gotten so-called "traveler's diarrhea" has possibly dealt with giardia before. However, because dogs may be unknowingly drinking contaminated water while outdoors, they are at risk for the disease here at home.

Giardia in dogs is quite common, so much so that there's a good chance your dog has Giardia in its intestines already. Keep in mind that these are single-celled organisms, so a small number of giardia is not enough to cause significant damage. In fact, VCA Animal Hospitals reports most dogs with Giardia do not exhibit any clinical signs, and most owners won't even be able to detect it.

It can become a problem, however, if the dog has ingested a large number of Giardia organisms. Drinking contaminated water or sniffing the ground where Giardia cells are present can transmit the illness to the animal. The giardia will attach themselves to the intestinal wall of the dog and may begin to do damage, which will result in a number of issues.

The most common clinical sign resulting from Giardia is diarrhea in dogs. Diarrhea caused by Giardia comes on suddenly and will likely be unusually foul smelling. The stool will likely be soft or watery, and may have a greenish tinge to it. In more advanced bouts of Giardia, the dog's feces may contain mucus or blood. Vomiting is another sign associated with this single-celled parasite, although not all dogs will exhibit this sign.

If your dog is exhibiting any of these signs, take them to a veterinarian as soon as possible. The vet will take a stool sample from the dog and analyze it for signs of Giardia and other infectious diseases. As diarrhea is a common clinical sign associated with numerous other diseases, the stool sample could point to a number of other issues.

Giardia is a potential zoonotic disease - meaning it can be spread from dogs to humans. Proper treatment of the infected dog as well as good personal hygiene and environmental disinfection are all key in avoiding infection in people. Giardia is treatable with medication.  An affected dog will likely be put on a drug regimen for approximately one week, which is usually sufficient to get rid of the problem. It is important to treat the environment in which the infected dog has been defecating and limit the dog’s exposure to the area where it became infected with Giardia. Giardia can become a recurrent problem if these steps are not taken. In addition, Giardia can pose a problem for dogs with weakened or ineffectual immune systems. In these cases, fighting the disease will likely be more difficult, and in rare cases could potentially be fatal.