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Giardia in Pets


Diarrhea. Boy, do I see lots of this, and when I say “lots,” I mean lots. In fact, on some shifts, it feels like that’s all I (and sometimes my clothing) see. One of the common causes of diarrhea in pets worldwide is Giardia. Giardiasis is caused by a single celled protozoan parasite that is transmitted by a fecal-oral route, meaning that the parasite is swallowed in food and water (think puddles, lakes and streams) contaminated with feces. Note: your pet does not have to eat feces to get the parasite!

Infection can be present without symptoms, but when signs are present, the most common one is diarrhea that results in the passage of large volumes of watery feces, oftentimes with blood and mucus. Weight loss, decreased appetite, and vomiting can occur as well.

How is the diagnosis made?

Diagnosis is often made by evaluation of fecal material under a microscope. However, this little parasite can be very difficult to find! Nowadays, we have a nifty little “snap test” which allows us to put some stool into a solution and cartridge that gives us a positive or negative result (like a pregnancy test for poop). This test is very sensitive at detecting the presence of giardia and it is what we use in addition to a fecal exam in our hospital.

How does one treat this parasite?

Generally, very easily and inexpensively, provided your pet doesn’t get so ill that they will need IV fluids or hospitalization. The little puppy pictured is named Rascal (a former Mug Shot Monday), and he was hospitalized due to an infection with Giardia. His diarrhea came on fast and furious, and because teeny puppies don’t have much “wiggle room,” it caused a critical drop in his blood sugar requiring more intensive hospitalization (he made a full recovery!).

Giardiasis is generally treated with an inexpensive antibiotic called Metronidazole (Flagyl) and it is readily available.  In small puppies such as Rascal, or dogs sensitive to this antibiotic, a dewormer known as Panacur can be used instead for five to ten days.

How do I prevent it?

This biggest way to help prevent infection is to keep your pet from drinking from puddles, lakes, streams, or other sources of stagnant water (I know, this can be difficult). It may also be advisable to treat other animals in the same household while treating the infected, symptomatic pet. There is a vaccine available for Giardia in dogs and cats, but most veterinarians don’t recommend it unless your pet is at really high risk or is one of those pets that get it frequently.

Don’t forget! People can get Giardia too! Younger children are at a higher risk as hands often find their way to mouths during outside playtime (grass can be contaminated with giardia cysts as well). And those adorable doggy kisses we love so much? Let’s just say that it is easier to accidentally ingest one of those little cysts than you might think.

There are also environmental control measures that can be taken to prevent reinfection. Pet parents should be vigilant in clearing fecal material from the environment. If your pet has been diagnosed with Giardia, it is often recommended that you wash as many areas of your environment as possible, followed by disinfection your premises with a solution of bleach diluted in water (another measure that is easier said than done).

As with anything medical, there is no one clinical sign that equals a definitive disease, and diarrhea is one of the most common clinical signs of any disease process. Because of this, if your pet has diarrhea that persists beyond 24 hours, or is very sudden and severe, a veterinary exam is in order.

2 Comments Post a comment
  1. As you remember, with Alexia we thought she was originally diagnosed by her regular Vet with Guardia (whether for real or not?) but when we brought her to you because she wasn’t responding to treatment, we found out she had Parvo, which normally attacks unvaccinated puppies, right? So, how do you deal with that situation, specially with puppies?

    March 8, 2012
    • Great question, Miguel! It is not uncommon for puppies to have multiple infections and we have to treat each of them concurrently… this often means many medications at once :(.

      It is common for pups to have Parvo (a virus, therefore no treatment per se, only support) AND Giardia (would need to give Flagyl) AND/OR Coccidia (would need to give Albon in addition to Flagyl)… we sometimes have to poly-pharmacy these little guys to cover all the parasites that are in their system.

      This is why when we see puppies, we generally run a parvovirus snap test, a giardia snap test, and a full fecal exam. Sometimes only a fecal exam is done, but as you know, that doesn’t necessarily mean that there is only one problem lurking. There are a lot of caveats in medicine that sometimes make a definitive diagnosis tricky, including the fact that giardia “sheds” intermittently, that you can have a negative parvo test one day and a positive the next, that some parvo strains don’t show up on the snap test, etc., etc., etc. It was so smart of you have have Alexia rechecked when she wasn’t responding to treatment, as the body is dynamic and changing constantly.

      Well, she is all dynamo now! 🙂

      March 8, 2012

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