How Do Dogs Get Giardia?

Dogs often get giardia from consuming contaminated water, food, or even through contact with other infected animals. This single-celled parasite is often present in feces and can survive for several months in certain environments.

Also, giardia cysts are resistant to most disinfectants, making them hard to completely eradicate from an environment. Central to prevention is ensuring a clean living environment for your dog and discouraging them from eating feces or drinking contaminated water.

Last Updated on September 20, 2023

Has your pet been suffering from diarrhea? Maybe after a trail in the woods or after a trip to the lake? He may be infected with a parasite called Giardia. What is it? Where can our dogs possibly get them?  

dog on a hike

What is Giardia?

Giardiasis or also sometimes referred to as “beaver fever” is an intestinal infection that can affect mammals counting dogs and humans. Giardia intestinalis (or Giardia lamblia) is a single-celled parasite that is present worldwide and causes the disease commonly called “Traveler’s Diarrhea.” People who love the outdoors may get this more often when ingesting contaminated water or food. Bodies of water like lakes and streams can also be a source of infection. 

There are two forms of Giardia: the mature parasites known as trophozoites and the cysts that infect. Trophozoites are a fragile, feeding form that lives in the small intestine of the infected animal where it multiplies until they become cysts. These cysts are then shed into the feces where other animals can get infected with the parasite. They can also survive in the environment for several months. 

How is it transmitted?

Your pet can get this parasite when he eats or drinks something that’s contaminated with fecal matter. As previously mentioned, Giardia can survive in the environment for a long time. But they specifically thrive in a cool and damp environment. Which makes water the number one source of contamination.

For example, your dog jumps in the lake (where ducks are also present) at a public park, he can get the parasite. Other scenarios also include your dog drinking water from a stream in the woods where deer might have passed by, drinks from a puddle where an infected dog’s poop might not have been picked up.

dog swimming

Even in places where there is no water source, your dog can still get the virus. For example: If an infected dog licks his behind and then licks another dog’s face. He can pass the parasite. Or if your dog steps on contaminated feces and then licks his paw, he can get the disease. An important detail to remember: not only humans and dogs can get Giardia. Other wild animals such as ducks, geese, raccoons, and squirrels can carry the parasite. Example:

If you have a water dish outside of your house for your dog, wild raccoons can bring the parasite and consequently infect your dog. Similarly, if a stray animal poops on your yard and your dog will go on to investigate, he can also get infected. Also, if your dog likes to put things in his mouth, be careful because he can also get the parasite from grass or from chewing sticks. What are the symptoms you should look out for?

Other readings you might also be interested in: Can Dogs Chew On Sticks?


If you and your dog have been out on a trail or a hike and he has drunk water from streams, then you should look out for any signs of infection. According to AKC, some of the symptoms of Giardia are the following: 

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

Symptoms usually show 1-3 weeks after the initial infection. When your pup gets the parasite, they attach to the intestinal wall and cause foul-smelling diarrhea. The stool may be mixed with blood and can range from watery to soft and appears light in color (usually with a greenish tinge). Some dogs, however, do not show any symptoms but can be diagnosed with Giardiasis. If your pup seems off, i.e., refuses to eat, has a low energy level, or having indigestion, call your vet immediately.

Giardia infection, generally, isn’t life-threatening. But senior dogs, puppies, and dogs with compromised immune systems may have more difficulty fighting off the parasite.

Diagnosis and Treatment

To test for Giardia infection, you will most likely need to supply several fresh stool samples to your veterinarian. Technicians look for antibodies and Giardia cysts to diagnose your pet with the bug. If they do, your pet will be given antiparasitic drugs and would need to undergo another fecal exam to confirm that there is no presence of the parasite anymore. There is no drug specifically formulated to treat Giardia infection. But with the right medicine, Giardia can be eliminated within 2 weeks

dog park

Can it be transmitted to humans?

Pet to human transmission is rare. But it can happen. The parasite known as Giardia is considered to be zoonotic. Meaning it can be passed from pets to humans and vice versa. But more often, contaminated municipal water supply is to blame rather than pets. Diarrhea, greasy stools, and digestive issues are the symptoms.


If you love to take your dog outdoors with you, carry a food bowl for his dog food and water. You can simply put it in your dog’s backpack. He’d love the added weight, especially if your dog is a large breed. You can check out the best dog backpacks here.

If your pup has been recently infected, clean surfaces with a beach-based cleaning product. Wash dog beds with hot water and soap. If you have other pets in the household, get them tested as well to prevent reinfection. Moreover, when you are in the great outdoors, keep an eye out for your pet. Especially when there are wild animals in the area or any standing water like puddles. 


Giardia is an intestinal parasite that causes watery diarrhea, vomiting, and lethargy in dogs. However, some dogs may not show any signs of illness. If he is acting odd, call your vet. He may have gotten the bug when you recently went out. There are a lot of possibilities to where your dog must have gotten the bug. But the most common source of infection is water. Provide a clean source of water for your dog to prevent infection such as Giardia.  

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