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Giardia in Dogs

Giardia is a parasite that makes its home in the intestines of mammals. This parasite is extremely contagious and potentially fatal in certain circumstances. Here, our Lacey vets discuss Giardia infections in dogs, the symptoms your pup may experience, and how it is treated and prevented.

What is Giardia in dogs?

Giardiasis is an intestinal infection that can affect both humans and animals. This infection is caused by the Giardia parasite.

Types C and D are the most common infecting viruses in dogs, while F is the most common infecting virus in cats. Types A and B apply to humans.

While Giardia in dogs does not always cause problems, when it does, the consequences are extremely unpleasant. Diarrhea is the most common symptom. Giardiasis is especially dangerous in puppies, dogs with weakened immune systems, and senior dogs.

Symptoms of Giardia in Dogs

If your dog is showing concerning symptoms of illness, your best bet is to book an appointment with your vet, since many of the signs below are common to several conditions. that said, owners can be on the lookout for several Giardia symptoms in dogs, including:

  • Weight loss
  • Dehydration 
  • Poor coat appearance 
  • Diarrhea 
  • Vomiting

Diarrhea and weight loss are common symptoms of parasitic infection because the parasite disrupts a dog's internal systems, impairing its ability to absorb water, electrolytes, and nutrients. Diarrhea can be continuous or intermittent, particularly in puppies. Severe weight loss and even death can occur if the disease is not diagnosed and treated.

How are dogs infected with Giardia?

As previously stated, this single-celled parasite lives in the intestines of mammals, birds, and amphibians and has several subspecies. While each subspecies focuses on a different group of animals, they all share the same lifecycle and mode of transmission.

Giardia has two stages in its lifecycle. Mature parasites (trophozoites) multiply and form cysts in the small intestine. Cysts become infective and are shed through the feces of an infected animal. They can survive in the environment as cysts for weeks before being ingested by another animal. They are then transformed into trophozoites and the lifecycle is repeated.

What happens if Giardia is left untreated in dogs? Well, it may cause severe, watery diarrhea that requires emergency veterinary care and can be fatal. This is especially true for puppies and older dogs.

Can I get Giardia from my dog licking me?

Fortunately, the risk of humans contracting Giardia from dogs is relatively low, but it can happen. Make sure to wash your hands after handling your dog's poop to reduce this low risk. 

Giardia transmission in humans is most commonly transmitted through drinking water, not through pets. Giardiasis is also known as "Beaver Fever" in humans. If your water source is known to contain the parasite, consider purchasing a water filter, and avoid drinking contaminated water, especially while traveling. This parasite can also be found in soil and on food, so wash all produce before eating it and thoroughly wash your hands after working with dirt.

How is Giardia treated?


  • Fenbendazole is a common deworming medication used to treat Giardia in dogs
  • An antibiotic called metronidazole might also be recommended
  • Your vet may suggest a combination of these two medicines


  • A prescription diet may be able to alleviate symptoms such as diarrhea

Preventing Giardia in Dogs

Giardia is a highly unpleasant parasite that cannot be prevented with the tick, flea, and heartworm preventatives that your dog would normally receive from a veterinarian.

There are, however, precautions you can take to keep your dog from contracting Giardia. 


  • Bathing should occur regularly to remove feces and cysts present on the fur and skin


  • Common household disinfectants and steam-cleaning all surfaces
  • Remove and dispose of all feces promptly (washing your hands thoroughly afterward)
  • Giardia cysts on the lawn are killed by direct sunlight drying them

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Is your dog displaying signs of a parasitic infection such as Giardiasis? Contact Olympia Pet Emergency to schedule an appointment.

Walk-in Patients Welcome

At Olympia Pet Emergency, you can always access our full complement of emergency services without an appointment. We treat both walk-in patients and referrals for urgent veterinary care.

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