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Giardia in Dogs: Symptoms, Treatment, & Prevention for Your Dog

Published on March 20th, 2024

Updated on October 15th, 2025

Written by Petco's Animal Care, Education and Compliance Team

Reviewed by Petco Editorial Team

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Giardia in Dogs: Symptoms, Treatment, & Prevention for Your Dog

A parasite that dogs can pick up from contaminated water and soil is Giardia. This one-cell parasite, called a protozoa, can cause diarrhea and other serious symptoms in humans and pets alike.

Giardia in dogs commonly spreads via contaminated water. Types C and D of the parasite are the most likely to infect your dogs, whereas humans are commonly infected with type A and B. Healthy dogs can usually recover fully, though veterinary intervention is most often indicated. Giardia symptoms in dogs are uncomfortable and may quickly lead to dehydration if not addressed. A visit to your vet may be required to aid with dehydration, receive prescription medication, and dog vitamins and supplements may be helpful after the parasite passes.

What causes Giardia?

The disease giardiasis is caused by the protozoan parasite Giardia and is most likely to affect puppies. Dogs in close quarters with other pets—such as those being boarded at a kennel—may also be more vulnerable. While any dog can come into contact with this parasite, healthy adult dogs may not show symptoms, and their body may resolve the infection without you even noticing.

Infected canines spread it to other pets by shedding parasitic cysts in their feces. If another dog comes along and sniffs at the poop or drinks from contaminated water, they contract the parasite and become sick with giardiasis. Giardia is often found in puddles and ponds.

Symptoms of Giardia in dogs

Some dogs never show visible symptoms of this parasite, but that doesn’t mean they’re not contagious. That being said, the primary signs of Giardia in dogs are diarrhea and vomiting. The diarrhea often smells especially foul and can be slightly green or contain mucus or blood. Other symptoms include; weight loss, this is more likely if left untreated for weeks, and a chronic intermittent diarrhea. This means your dog may have periods where they to be “all better”, only for the diarrhea and subsequent signs of giardia to return after a few weeks.

The Giardia parasite in dogs can also lead to excessive gas and listlessness. Make sure you give any dog with diarrhea plenty of water because they can quickly become dehydrated and deteriorate.

Pay special attention to dogs with weaker immune symptoms. This includes puppies, seniors and pets with known underlying health problems, as they’re at a higher risk of getting extremely sick from a parasitic infection.

Diagnosing Giardia in dogs

Giardia cysts are often too small to detect on a routine fecal smear in clinic. Instead, if your veterinarian suspects giardia, they may use a specific test to search for the presence of Giardia specific antigens, or cell proteins, within a stool sample. If your pet has clinical signs like diarrhea, your vet will consider that when diagnosing and recommending treatment.

Treatments

Treatment for Giardia in dogs can include a variety of veterinary services, including:

Medication Your veterinarian may prescribe fenbendazole, metronidazole to help kill the parasite. These medications are effective against a broad spectrum of parasites and may be used in combination to increase effectiveness.

Bathing You may be asked to bathe your dog more often to help remove cysts from their coat, and special shampoo may be recommended.
Clean up It’s more important than ever to use dog poop bags and clean-up supplies when your pet has Giardia. Use a 1:32 or 1:16 diluted bleach solution to disinfect areas where your pet has had an accidental bowel movement indoors.
Rehydration Since diarrhea is the most common symptom of your dog’s Giardia, your pet may need additional care. Have lots of water on hand and consider supplementing dry dog food with more wet food containing added moisture.

Can people get Giardia from dogs?

The most common types of Giardia in dogs are C and D, while the A and B genotypes of this parasite are the most likely to infect humans. For this reason, dogs are unlikely to transmit their parasite to their pet parents—though it’s not impossible. You may want to take special precautions if you have a health condition that weakens your immune system. All pet parents should wash their hands thoroughly after cleaning up dog waste or handling pups who have Giardia.

Prevention

Thankfully, avoiding Giardia throughout your pet’s life may be possible. Don’t allow your dog to drink from outdoor water sources like ponds, lakes and puddles that contain untreated water. Also make sure they don’t sniff around or eat something that could be contaminated with another dog’s waste. Keep your pet’s vaccinations up to date and keep an eye on their overall wellbeing—this can’t prevent parasitic infection altogether, but it might help your pup avoid a more serious case.

Prognosis for Giardia in dogs

The prognosis is generally positive for dogs who contract Giardia. Some pets remain carriers in the long term, but with the right medication and plenty of rest, your dog may bounce back within days. Remember that reinfections are possible, so you should talk to your veterinarian if you notice the symptoms again.

FAQs about Giardia

How did my dog get Giardia?

Most dogs get Giardia from drinking untreated water, like from a pond contaminated with parasites. Your pet may also get this parasitic infection from sniffing another pet’s feces or scat from a wild animal living near your home. Giardia may also infect water sources at public kennels or anywhere a large group of dogs live in close quarters.

What does dog poop with Giardia look like?

The most common Giardia symptom in dogs is diarrhea. Your pet’s poop may also be slightly green or have mucus and blood in it, which are signs that your dog needs medical treatment.

How serious is Giardia in dogs?

The most common Giardia symptom in dogs is diarrhea. Your pet’s poop may also be slightly green or have mucus and blood in it, which are signs that your dog needs medical treatment.

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Giardia in Dogs: Symptoms, Treatment, & Prevention for Your Dog

What causes Giardia?

Symptoms of Giardia in dogs

Diagnosing Giardia in dogs

Treatments

Can people get Giardia from dogs?

Prevention

Prognosis for Giardia in dogs

FAQs about Giardia

How did my dog get Giardia?

What does dog poop with Giardia look like?

How serious is Giardia in dogs?

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Giardia in Dogs: Symptoms, Treatment, & Prevention for Your Dog

What causes Giardia?

Symptoms of Giardia in dogs

Diagnosing Giardia in dogs

Treatments

Can people get Giardia from dogs?

Prevention

Prognosis for Giardia in dogs

FAQs about Giardia

How did my dog get Giardia?

What does dog poop with Giardia look like?

How serious is Giardia in dogs?

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