Giardia Infects Pets And People
An Unpleasant, But Important, Topic
It’s a parasitic infection of the small bowel that can prevent proper absorption of nutrients, damage the intestinal lining, and interfere with digestion…but not always.
In the pet world, dog owners tend to be more familiar with it, but it can infect cats, and rodents such as hamsters, gerbils and guinea pigs, too. It also can infect some livestock and wildlife species.
This is where it gets distasteful, folks. Giardia is contracted when you swallow a cyst from the stool of an infected animal.
“But how can that happen?” you ask. In humans it happens more frequently in developing countries where treated water is less common, but otherwise folks can get it from contaminated drinking and swimming water and interaction with infected animals.
Dogs become infected by drinking contaminated water, eating contaminated food, licking contaminated fur or otherwise coming into contact with contaminated feces…like when they eat it. Then they want to give you a big kiss.
Young dogs, old dogs, and those with compromised immune systems are more susceptible, but the good news is: it’s treatable.
Two drugs are used most commonly: Metronidazole, an antibiotic (back on the block we called it Flagyl) and fenbendazole, a dewormer.
Livestock and pet folks may recognize the latter as the Panacur or Safe-Guard at your pet supply or feed & grain store.
I’ve never tasted the stuff personally, but they say Metronidazole has a bitter taste, which probably makes it difficult to administer.
Some of these drugs reportedly can also cause anorexia, depression and vomiting. There are other deworming meds on the market as well, but although they're effective against the parasite, they can also have some harmful side effects.
What they don’t know about the parasite is as plentiful as what they do know. For example, they don’t know how many species of Giardia there are and which species affect which animals.
There is disagreement in the vet community on how common such infections are and when they should be treated.
Generally, they believe that infection is common but disease is rare, the difference being that some dogs carry the parasite (infection) without visible clinical signs.
Dogs with the disease will show signs such as diarrhea, loss of appetite, malnutrition, weight loss, fatigue, weakness, and stools that are bloody or pale-colored, greasy, and strong-smelling.
Another source of confusion is diagnosis. In researching the disease, I found one source that says, “it’s not difficult for veterinarians to diagnose,” while another says, “Giardiasis is very difficult to diagnose because the protozoa are so small and are not passed with every stool.” I’d have gone crazy looking for a consensus. We report, you decide.
But in 2004 the cavalry showed up in the form of an advanced diagnostic tool called ELISA technology. It stands for Enzyme-linked immunosorbent assay.
The assay takes the veterinarian less than an hour to perform at the clinic using a small sample of diluted stool.
Does that settle the “easy diagnosis/difficult diagnosis conundrum?” he wonders.
Giardia, though, is the gift that keeps on giving. Its life cycle is complex and although subsequent stool tests may be negative, parasites can still live inside the dog’s GI tract.
Your dog then becomes a source of potential re-infection, infection for other animals, and possibly for people.
Because of the way the parasite is spread, it’s a good idea to regularly clean and disinfect food and water bowls, and to be careful when scooping poop.
And, of course, always wash your hands after interaction with your dog.
That's especially important for small children, who aren't responsible about their personal hygiene, and who often put their fingers in the mouths.
© 2012 Bob Bamberg