Giardia In Dogs (Symptoms, Causes & Treatment)

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Dogs can get GI symptoms for several reasons, resulting in vomiting, diarrhea, abdominal pain, and lack of appetite. When your dog stops eating or experiences severe, watery diarrhea, it likely warrants a trip to the vet. While some dogs experience diarrhea more often than others based on their health, various allergies, or dietary indiscretion, repeated, long-lasting diarrhea could indicate something more serious. If you're wondering why your dog has diarrhea, it could be Giardia. 

What Is Giardia?

Giardia is a type of parasite that lives in the intestines of dogs and other animals like cats. It causes severe GI symptoms and disease that can be harmful to your pet's health if not treated. This single-celled microscopic parasite is spread through the feces of infected pets, contaminated water, food, and soil. In addition, it's extremely contagious, and humans can get Giardia from their pets.1 Therefore, Giardia in dogs can be spread to you if you're caring for an infected animal, so it's important to decontaminate your home if your dog is diagnosed. 

The lifecycle of the Giardia parasite has two stages: cysts and mature parasites. The mature adult parasites, also known as trophozoites, live in the dog's small intestine, multiplying and becoming cysts. Cysts are when they're infective and are shed through the feces of an infected animal, surviving in the environment for weeks until they find a new host and repeat their lifecycle.2

Giardia parasites can survive in the cold, including in water and soil, surviving longer in colder temperatures during the winter. It also prefers moist, cool environments instead of warm environments with direct sunlight.3

Unfortunately, dog Giardia is relatively common. This parasite infects almost 15% of dogs.4

How Do Dogs Get Giardia?

Because Giardia parasites can live in the environment for a long time, there are many ways a dog can become infected, including: 

  • Coming into contact with infected feces from another animal
  • Playing in contaminated soil
  • Licking themselves after coming into contact with a contaminated surface
  • Drinking water from a contaminated source, such as a creek or pond
  • Being in a dirty crate or litter box3

It's important to note that ingesting feces doesn't mean directly eating an infected animal's poop. It can mean sniffing soil or sniffing an infected dog's rear end and then licking their nose.1

Once the parasite reaches the dog's intestines, it can multiply and spread through feces, even if the dog isn't showing any signs of illness. If you have more than one dog in your household, it's easy for the second one to become infected. However, transmission from dogs to cats and vice versa is less likely than transmission from dog to dog.2 If one of your pets has Giardia, you should try to prevent your other dog from getting it, so you should take certain precautions, like separating them and decontaminating your home. 

Is It Contagious?

Dog Giardia is extremely contagious. If your dog touches an infected animal's feces, directly or indirectly, they can get infected when they swallow the cysts.3 Therefore, since transmission is highly likely if your dog comes into contact with an infected animal, it's important to take them to the vet as soon as possible for diagnosis and treatment. 

Can Humans Get Giardia From Pets?

Giardia can be passed from pets to humans. However, it's rare for humans to get infected with Giardia from dogs. But, of course, it can happen, so if your dog is diagnosed with the parasite, you should take the proper precautions when caring for them, such as washing your hands and avoiding touching your face. Luckily, the risk of getting Giardia from your dog is relatively low.

In addition, a different type of Giardia infects humans, but some strains can be shared. Humans typically get Giardia by drinking infected water, not directly from pets. Therefore, you should avoid drinking potentially contaminated water. Giardia can also be found in food and soil, so you should wash fruits and vegetables, especially if it's possible an infected animal came into contact with your food.2

Symptoms Of Giardia In Dogs

Giardia symptoms in dogs resemble those of other parasites and GI issues, so diagnosis is important if you believe your dog has been infected. The most common symptom of Giardia in dogs is diarrhea because the parasites feed on the intestines, affecting the body's ability to absorb nutrients, including water, potentially leading to diarrhea and weight loss. Additional symptoms of dog Giardia include nausea, vomiting, lack of appetite, and abdominal pain. 

Giardia diarrhea in dogs can lead to severe dehydration, especially if it's continual, so you should have your dog treated as soon as possible to prevent severe side effects caused by dehydration.2 Giardia in puppies with developing immune systems and adult dogs with compromised immune systems due to underlying illnesses is especially dangerous.2

When Should I Take My Dog To The Vet?

You should take your dog to the vet if you believe they've come into contact with the parasite, whether by drinking contaminated water or having contact with an infected dog. Since Giardia causes unpleasant GI symptoms that can cause severe dehydration, you should have your dog treated immediately, especially if you have other pets in the household that can be infected. 

Additionally, since it's possible for humans to be infected with Giardia through their pets, you should take your dog to the vet to have them diagnosed to determine whether you and your family need to take the proper precautions and decontaminate your home. 

Giardia Diagnosis & Treatment

Giardia is diagnosed in several ways. First, your vet will discuss your dog's symptoms and possible incidents that may have led to infection. They'll ensure your dog isn't suffering from dehydration while checking for pain, gas, and other Giardia symptoms in dogs. 

The best way to diagnose Giardia in dogs is to eliminate other possible causes of your dog's symptoms. They'll use a fecal test to check for parasites, microscope evaluation to look for the parasite, and a parvo test. 

Giardia in dogs is treated with medications such as metronidazole. Dogs may need multiple rounds of treatment because it can be virtually impossible to remove the Giardia cysts from around your home with one decontamination. Dogs can easily become reinfected if the cysts aren't fully removed from the home. Therefore, your dog might need to continue to be treated for the parasites until your home is free of them. In most cases, the infection will be cleared after one round of treatment.1

If your dog is dehydrated, they may receive IV fluid therapy, electrolytes, and vitamins. However, severely dehydrated dogs may have to be hospitalized and monitored regularly overnight.1

Unfortunately, dogs can become reinfected with Giardia because they don't build immunity to it. Therefore, you should disinfect your home with bleach or steam cleaning to kill the cysts. You should also dispose of your dog's feces when your dog poops in the yard or on walks. 

Preventive Tips

Giardia is extremely contagious, and your dog can get it almost anywhere. Since dogs like to sniff other dogs' rear ends, you should be careful at the dog park and never let your dog sniff another dog's poop while on walks. In addition, you should take precautions even in your own home because Giardia can infect other pets and humans. Unfortunately, while some flea and tick medications protect against parasitic infections, they do not protect against Giardia. Here are a few tips to help you prevent Giardia in dogs:

  • Wear gloves when gardening to reduce the risk of coming into contact with infected soil. 
  • Remove standing water from your yard your dog may drink. 
  • Clean your household surfaces regularly with steam and disinfect dog toys, bedding, water, and food bowls. 
  • Wash your hands with soap and water after touching your pets, their toys, and treats, and picking up their poop.3
  • Schedule Giardia testing before bringing home a new dog. 
  • Clean litter boxes daily.
  • Prevent your dog from eating cat poop from the litter box.
  • Never let your dog come into contact with an unknown dog or cat. 
  • Don't let your dog hunt rodents or other small animals.
  • Visit your vet regularly for fecal parasite testing. 

Since Giardia can be dangerous to your pet, especially if it causes severe dehydration, it's always best to prevent it. Unfortunately, you can't control everything, but there are a few things you can do to prevent Giardia in dogs. 


What does Giardia poop look like?

Unfortunately, you won't be able to see Giardia parasites in dog poop to know if a dog is infected. Other parasites, like roundworms, are visibly detectable. However, if your dog has Giardia, their diarrhea will be soft, watery, and foul-smelling. Unfortunately, for some pet parents, this type of diarrhea isn't enough to warrant a trip to the vet. However, if your dog has continual diarrhea or the stool doesn't improve after a day or two, you should take your dog to the vet for diagnosis and treatment.

Additionally, since you can't see the microscopic parasite in stool, you should never let your dog sniff another dog's rear end or feces while on a walk. Dogs are curious creatures and like to smell things that typically smell unpleasant to us. However, getting the cyst on their nose, then licking their nose, can cause them to become infected with Giardia.  

How long does Giardia stay in my dog?

Giardia can live in the environment for many weeks, and they stay in your dog's intestines for up to 12 days before the cysts come out in the stool. Once your dog starts treatment, your dog will likely be fully recovered within a few weeks. However, it typically takes multiple negative tests to confirm your dog is no longer infected with the parasite. 

Since these parasites can live in the environment, your dog can easily become reinfected if there are cysts in the home. After multiple negative tests, however, you can be certain you've removed the cysts from the environment, and your dog won't be reinfected. Of course, dogs can still be reinfected throughout their lives, so it's important to know when to take your dog to the vet for treatment. 

What happens if Giardia goes untreated in my dog? 

If Giardia goes left untreated in dogs, it can lead to severe weight loss, dehydration, and death because of these symptoms. Since Giardia can cause continual watery diarrhea, dogs can lose water faster than they can replenish it, and that dehydration can be fatal. 

Sick dog cuddling with stuffed animal

Final Notes

Giardia in dogs is fairly common, affecting up to 15% of dogs throughout their lives. Unfortunately, there are many different causes of Giardia, including your dog playing in infected soil. Since you can't see these parasites, it can be difficult to protect your dog. However, getting them treatment as soon as possible is crucial to ensuring their health. 

Giardia will not go away on its own and must be treated with medication, so don't wait to get your dog the help they need. If your dog has continuous watery diarrhea, contact a vet as soon as possible to prevent dehydration. Dutch can help diagnose and treat parasitic infections from the comfort of your own home. Talk to a Dutch vet today. 



  1. “Giardia in Dogs.” PetMD,

  2. Burke, Anna. "What You Need to Know about Giardia in Dogs." American Kennel Club, 4 Mar. 2022,

  3. "Giardia and Pets." Centers for Disease Control and Prevention, 26 Feb. 2021,

  4. "The Causes, Symptoms, and Treatment of Giardia in Dogs." WebMD,

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