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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Parasite Affects Dogs And People

Mary Sagal Correspondent

Heading afield with your dog might seem the perfect way to spend the long, sunny days of late summer. After all, running through a meadow on a cloudless morning or meandering along a forest path with your canine pal are some of life’s finer pleasures.

But before you get lost in your outdoor fantasies, take note. Something as benign as letting your dog drink from a stream could end in a trip to the veterinarian’s office.

Dogs, like people, can get an intestinal illness called giardia.

“Giardia has been affecting dogs for many years,” said Stephen Barr, a professor at the Cornell University College of Veterinary Medicine in Ithaca, N.Y., who has been researching giardia in dogs and cats. “Most dogs get it from other dogs, but it can be passed on to dogs from some other animals, too, including wildlife.”

Giardia illness is caused by a protozoan parasite that affects the intestinal tracts of people and most domesticated animals.

It’s spread by fecal-oral transmission, meaning that some form of the organism - usually a cyst - is shed in the feces of the infected person or animal, then inadvertently eaten or drunk by some other person or animal.

Once in the intestinal tract, the giardia parasite may or may not cause giardia illness. It is possible for a dog or person to ingest the parasite, not experience any symptoms of the illness yet be able to pass it along to others, Barr said.

According to Delbert Carlson, a veterinarian, and James Giffin, a physician, co-authors of “The Dog Owner’s Home Veterinary Handbook,” the main symptom of giardia illness in dogs is diarrhea, sometimes mixed with mucus and blood. In people, symptoms include diarrhea, cramping, nausea, vomiting, headache and low-grade fever.

Sources of giardia vary, partly because there are several different species of the parasite.

Barr said dogs can contract giardia from other dogs and from wildlife. People can get it from other people, from wildlife and possibly from dogs, although Barr said the dog-human transmission has not yet been confirmed.

At home, Barr said dogs usually pick up giardia by coming in contact with the feces of infected dogs. People usually get it from drinking sewage-contaminated drinking water.

In the outdoors, stream water is a big concern for both people and dogs. Some wild animals live in or congregate at streams, depositing feces nearby or in the water. Giardia cysts - shed in the feces of infected wild animals - can remain viable in water for months, particularly in cold streams.

Human waste can also contaminate stream water with giardia cysts, a problem that has grown proportionately with the popularity of outdoor sports. Unfortunately, there are few among us who know proper outdoor bathroom skills. (Kathleen Meyer has written an excellent resource; ask your bookseller.)

To avoid giardia while afield, Barr recommends boiling stream water before drinking it yourself or giving it to your dog.

If your dog shows symptoms of giardia, see your veterinarian immediately. Diarrhea can cause dehydration.

Veterinarians can use several tests to check for the disease. Most tests require a stool sample be brought to the vet’s office, sometimes for three consecutive days.

There are several drugs used to treat giardia in dogs. Barr said all are given orally. He said the illness is rarely fatal.

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