February 10, 2023
Giardia
Medically Reviewed by Dr. Erin Miller, DVM on August 11, 2026
What Is Giardia?
Giardia is a protozoal intestinal parasite. Pets pick up the parasite in the environment. Giardia cysts (eggs) survive well in soil and water and thrive in cool, moist conditions. Our pets can get giardia by drinking standing water (such as puddles and small ponds), eating other animals’ stool, or licking it off their fur after walking through something contaminated with giardia. In Bend, we see a lot of dogs with giardia. Most likely this is due to the large number of dogs socializing with other dogs, along with all the wildlife in the area, both of which give the parasite plenty of opportunities to spread.
What Are the Symptoms of Giardia?
Symptoms can vary greatly. Some pets will get sick and have diarrhea, decreased appetite, and vomiting. Other pets will have soft stool, stool with mucus, or even intermittent changes to the stool. There are pets who will have no symptoms at all, which is one reason a fecal test rather than symptoms alone is the only reliable way to know for sure.
How Is Giardia Diagnosed?
It is diagnosed by a fecal test. A fecal test can be performed if you bring your pet’s stool into your veterinary clinic (a lot of veterinary clinics send the stool out to a lab for fecal testing as part of our in-house and reference lab diagnostics). If your pet has a significant infection, then giardia cysts will be seen. Often a giardia ELISA test is also performed, which checks for the presence of an antigen, or exposure, to giardia. Because giardia can shed on and off, a single negative test does not always rule it out if symptoms continue, and your veterinarian may recommend retesting.
Is There a Treatment for Giardia?
Yes, there is treatment. Some pets will require multiple rounds of medication to clear the infection. This is especially common in puppies and kittens. Treatment options include Metronidazole or Fenbendazole, sometimes both together, since combination therapy often clears both symptoms and cyst shedding more reliably than either medication alone. Pets with a healthy immune system are more resistant to Giardia and will sometimes clear the infection on their own. Young, senior, and immuno-compromised pets are more susceptible and have a harder time clearing the infection. We often put pets with Giardia on a probiotic to help support a healthy digestive tract while they recover.
After treatment, we typically recommend a recheck fecal test about two to four weeks later to confirm the infection has cleared, especially in multi-pet households or if your pet’s symptoms return.
Is Giardia Contagious?
Giardia is contagious from dog to dog, so if you have other dogs in your household or that your pet frequently interacts with, they should have a fecal test to see if they need treatment.
There are different strains, or assemblages, of Giardia, and while humans and cats can get Giardia too, they rarely get it from dogs because the strain most commonly found in dogs does not typically infect humans. Direct dog-to-cat transmission is uncommon for the same reason, though young kittens in a household with an infected dog are sometimes tested out of caution. To be on the safe side, make sure to wash your hands before you eat, especially after handling your pet or cleaning up after them.
What Do I Do About the Environment?
Because giardia cysts stick to dog fur, we recommend bathing your dog once weekly until the infection has cleared. You should also pick up your dog’s poop immediately after they go to minimize contamination of your yard or the environment. This can reduce the chance of reinfection for your pet.
Cysts are killed in the environment by freezing temperatures or direct sunlight. Organic material, such as soil, vegetation, or stool, will shield cysts, making decontamination difficult or impossible in natural environments. Household cleaners will kill Giardia on hard surfaces, and quaternary ammonia compounds are most effective. Washing is effective for bedding or clothing.
If your household has recently dealt with giardia, it is worth reviewing our post on intestinal parasites common in Central Oregon and our broader guide to parasites in our pets, since giardia often shows up alongside other environmental parasites in dogs that spend time on trails, at dog parks, or near standing water.
For additional information you can also visit veterinarypartner.com (https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4952529).
If you have questions, please feel free to contact us at Pawtown Veterinary Care.
Frequently Asked Questions About Giardia in Pets
Can my cat get Giardia from my dog?
It is uncommon. The Giardia strains typically found in dogs rarely infect cats, and vice versa. Even so, in multi-pet households dealing with an active infection, a fecal test on all pets is a reasonable precaution, especially for young kittens.
How long does Giardia treatment take to work?
Most pets improve within a week of starting medication, though some require a second or third round to fully clear the infection, particularly puppies, kittens, and pets with weaker immune systems. A recheck fecal test two to four weeks later confirms whether treatment was successful.
Can I get Giardia from my pet?
The risk is low. The Giardia strains most common in dogs and cats rarely infect humans. Basic hygiene, like washing your hands after handling your pet or cleaning up stool, further reduces any risk.
Do I need to retest my pet after treatment?
We generally recommend it, especially if symptoms persist or your pet lives with other animals. Giardia cysts can shed intermittently, so a recheck fecal test gives a clearer picture than watching for symptoms alone.
How can I prevent Giardia in my yard?
Pick up stool promptly, limit access to standing water like puddles or ponds, and keep bedding and toys washed regularly. Giardia cysts are broken down by direct sunlight and freezing temperatures but can persist in shaded, moist areas for longer.
About the Author
Co-Owner and Veterinarian, Pawtown Veterinary Care
Dr. Miller is a co-founder of Pawtown Veterinary Care in Bend, Oregon, where she and Dr. Lauren Stayer built a practice centered on honest communication and compassionate, family-centered care for dogs and cats across Central Oregon.