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Giardia: The Puppy Parasite to Watch Out for This Summer

If your dog drinks from puddles or splashes around in lakes, read this.

by Dr. Shea Cox, DVM, CVPP, CHPV
Updated June 3, 2022
Dog drinking water from a puddle in the road
Lazy_Bear / iStock

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As a vet, I see lots of diarrhea — and when I say “lots,” I mean lots. One of the common causes of diarrhea in dogs worldwide is giardia, a parasite that dogs get from drinking from puddles, lakes, streams, or other sources of stagnant water. While it’s a year-round risk, giardia cases peak in the summer because people and pets spend more time outdoors and traveling. Here’s everything you need to know about giardia in dogs, including how to spot it, treat it, and prevent it from happening in the first place.

What is giardia?

Giardia is a ubiquitous single-celled protozoan parasite that can live in the intestines of dogs. The parasite thrives in cool, moist environments and can survive for months in the right conditions. Giardia can infect dogs, cats, wild animals and people too.

Giardiasis is transmitted by a fecal-oral route, meaning that the parasite is swallowed in food and water contaminated with feces. Your pet does not have to eat poop to get the parasite. In fact, dogs most commonly get giardia by drinking from contaminated water sources (think: puddles, gutters, lakes, and streams).

What are the symptoms of giardia in dogs?

Symptoms of giardia in both people and dogs can include diarrhea, gas, abdominal discomfort, nausea, and vomiting. That said, an infection can be present without symptoms. Not all dogs show symptoms of a giardia infection but when they do the most common symptom is watery diarrhea. Additional signs of giardia in dogs may include:

  • Severe diarrhea (often with blood and mucus)

  • Weight loss

  • Decreased appetite

  • Vomiting

  • Gas

  • Dehydration

  • Dry or poor coat appearance

If your dog has diarrhea that persists beyond 24 hours, or is very sudden and severe, take them to the vet ASAP.

How is giardia diagnosed?

Diagnosis is often made by evaluating fecal material under a microscope. However, this little parasite can be difficult to find. So, in addition, we use a nifty “snap test,” adding some stool to a solution that gives us a positive or negative result for giardia (like a pregnancy test for poop). This test is very sensitive to the presence of giardia in dogs.

How is giardia treated?

To treat giardia in dogs, veterinarians will typically prescribe a combination of fenbendazole (dewormer) and metronidazole (antibiotic) for about 10 days. In small puppies or dogs sensitive to this antibiotic, a dewormer known as Panacur can be used instead for five to 10 days. Your pet’s poop should be retested two to four weeks after finishing the medication.

Most healthy dogs make a full recovery from giardia. In some cases, supportive treatment, including IV fluids and hospitalization, may be required if dehydration or severe diarrhea persists. Puppies, senior dogs, and those with compromised immune systems are at higher risk for complications, including death. Your veterinarian will determine the best course of treatment.

How can I prevent my dog from getting a giardia infection?

The best way to prevent a giardia infection is to keep your dog from drinking from puddles, lakes, streams, or other sources of stagnant water. (I know, this can be difficult.) Dog park puddles carry a higher risk than, say, fresh rainwater pooled in a birdbath or fountain. Remember, giardia is transmitted by orally, and what better place to have concentrated levels of poop than a dog park, especially when some pet parents are not diligent about removing their dog’s poop.

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, but most veterinarians don’t recommend it unless your dog is at really high risk or is one of those pets who gets giardiasis frequently.

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

  • Pick up your dog’s poop frequently.

  • If you have cats (indoors or outdoors), pick up their poop too.

  • Clean your dog’s bowls regularly with soap and water.

  • Wash your dog’s toys and bedding often.

  • Disinfect areas such as crates and kennels

  • Avoid walking your dog in moist areas where other dogs or wildlife may have pooped.

Can I get giardia from my dog?

It’s possible to get a giardia infection from your dog but unlikely. There are several kinds of giardia and dogs are most commonly infected with a variant that doesn’t infect humans. Younger children are at a higher risk since their hands often find their way to their mouths during outside playtime (grass can be contaminated with giardia cysts as well). But if you love kisses from your dog, you may want to avoid them if your dog has giardia since you could accidentally ingest one of those little cysts.

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Dr. Shea Cox, DVM, CVPP, CHPV

Dr. Shea Cox is the founder of BluePearl Pet Hospice and is a global leader in animal hospice and palliative care. With a focus on technology, innovation and education, her efforts are changing the end-of-life landscape in veterinary medicine.