Giardia in Puppies: An Integrative Approach

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If you have a puppy, chances are you’ve heard of Giardia. It’s one of the more common parasites we find in young dogs. While it sounds alarming, it’s often more of a nuisance than a serious concern.

Many puppies with Giardia show no symptoms at all. When symptoms do appear, the most common one is diarrhea or an upset stomach. Even then, Giardia doesn’t usually cause long-term harm, especially if it’s caught early and managed appropriately.

That being said, I have found that Giardia can show up differently based on location. When I worked as a veterinarian in other cities – like San Francisco or Denver – I found that some dogs could have severe illness from Giardia (lethargy, inappatence, etc.), while in Los Angeles, I rarely see such severe symptoms. There may be different strains of Giardia depending on where you live.

How Do We Find Giardia?

Giardia is a microscopic parasite. That means you won’t be able to see it in the stool.

The most common dewormers given to puppies, such as Strongid (Pyrantel Pyomate), don’t treat Giardia. So just because your puppy has been “dewormed” doesn’t mean they are safe from Giardia. When in doubt, it’s good to check!

As a general rule, it’s always good to have your veterinarian run a fecal test on your puppy or young dog. Parasites become less common in adult dogs, but can be quite common in puppies.

There are two main tests that look for giardia (I recommend that you check both):

1. Fecal Flotation:

This is the standard stool test that looks for active Giardia cysts (eggs). If this test comes back positive, it means your puppy is actively shedding Giardia and should be treated.

2. ELISA or PCR test:

These are more sensitives test that look for genetic material and can be positive with recent exposure to Giardia. A positive result doesn’t necessarily mean your puppy currently has an active infection—it simply means they’ve been exposed in the past. In some cases, the immune system clears the parasite on its own. ELISA or the PCR result can stay positive for weeks or even months after the exposure is gone.

That being said, this test should eventually be negative. So it is good to check a stool test after two months to make sure that the parasite is gone.

What If My Puppy Has a Positive ELISA Test but no cysts?

A positive ELISA with no cysts (meaning no active infection) and no symptoms leaves you with a few options. There’s no “right” answer—it really depends on your comfort level and what your veterinarian recommends.

Option 1: Treat Proactively

If you’d rather not take any chances, treating your puppy “just in case” is a valid option. Common pharmaceutical options for treating Giardia include either Fenbendazole or Metronidazole.

Option 2: Wait and Watch

If your puppy isn’t showing any symptoms, it’s perfectly reasonable to take a “wait and see” approach. Some puppies will develop soft stools over the coming weeks, which may signal that Giardia is still present and the immune system could use some support. If that happens, you can always treat at that time.

Keep in mind that the ELISA or PCR test may show up positive for up to 2-3 months. If you have already treated your puppy but the ELISA or PCR is still positive, it is ok to wait two months and recheck to avoid overtreatment (assuming the symptoms are gone).

Medication Options

The two most common medications for Giardia are:

Metronidazole (an antibiotic)
Panacur (Fenbendazole) (a dewormer)

Studies show Panacur may be more effective at clearing Giardia, but in practice, I’ve found that it causes slightly more stomach upset.

If a puppy is already having diarrhea and has an active Giardia infection (ie has cysts present), in the past, I leaned towards Metronidazole since it is better at treating symptoms. However, my approach has changed recently due to new research coming out about Metronidazole’s negative effects on the microbiome.

If a puppy doesn’t have symptoms, in studies Panacur has shown slightly better efficacy than Metronidazole at clearing Giardia. Panacur will also clear out other parasites like round worm and other ascarids. So if you have multiple parasites, it might be a better choice.

What is the downside of medication?

There are more studies coming out showing that show that Metronidazole may cause negative effects on the microbiome (good bacteria in the gut).

Here is a link to a study that showed that a 14-day course of Metronidazole caused decreased microbial richness and significant reductions in Fusobacteria (a dominant phylum in dogs) and Bacteroidetes. These changes persisted for at least 4 weeks post-treatment in nearly half the dogs studied. Microbiome composition did not fully recover to baseline after 4 weeks, with some dogs showing persistent dysbiosis.

Panacur tends to spare more of the good bacteria, as shown in this study.

As a side note, in recent years, Panacur (fenbendazole) has gained popularity as an alternative cancer therapy, with some people even taking it multiple times a week without noticeable side effects. While I remain intrigued about its use for cancer, I do believe it’s an area that still deserves more research.

What About Holistic Treatments?

Some pet parents prefer a more natural route. While there aren’t published studies confirming the effectiveness of holistic Giardia remedies, some products may offer gentle support with minimal risk. Here are a few options that some of my pet parent clients have used:

🌿 Amber Naturalz Kochi Free More about it here
🌿 Diatomaceous Earth from Wolf Creek Ranch

These options fall into the category of “might help, won’t hurt” and can be a good starting point for holistic care.

Chinese herbal treatment for Giardia

In my next blog post on this topic, I will discuss Chinese herbs that I use for chronic Giardia – basically what I use when pharmaceuticals don’t work.

I have now had a few cases that responded well to the formula made by Evergreen called Wu Mei Wan.

I am still gathering case studies on this herb, but so far, most puppies and older pets seem to respond well to this formula for chronic Giardia.

Preventing Re-Infection

Puppies love to lick everything—including their own behinds—which is how Giardia often comes back. To reduce the chances of re-infection:

Gently wash your puppy’s backside after bowel movements with warm water and mild puppy shampoo
Pat dry with a soft towel
Keep play areas as clean as possible

For more info on environmental cleanup, check out these links:

Final Thoughts

Whether you choose to treat right away, monitor and wait, or try holistic remedies, know that most puppies recover fully from Giardia.

That said, if your pet has been treated but continues to test positive or show symptoms, there may be something deeper going on. In my next blog post, I’ll share what I’ve learned about persistent Giardia cases and what to do when standard treatments don’t work (Coming soon!)