Giardia in Dogs: Symptoms, Causes, Treatment

Updated: June 19, 2023


Giardia is a common parasitic infection that affects dogs worldwide. It is caused by a microscopic parasite called Giardia duodenalis (formerly known as Giardia lamblia), which primarily affects the gastrointestinal tract of dogs. This parasite can also infect humans and is considered a zoonotic disease, meaning it can be transmitted between animals and humans.

Giardia infection in dogs typically occurs through the ingestion of contaminated water or food, as well as direct contact with infected animals or their feces. The parasite has a complex life cycle that involves two stages: the cyst stage and the trophozoite stage. The cysts are the infective form and can survive in the environment for prolonged periods, while the trophozoites are the active form found in the dog’s intestines.

Dogs infected with Giardia may display various symptoms, including diarrhea, vomiting, weight loss, and lethargy. However, some infected dogs may show no apparent signs of illness. Diagnosis of Giardia in dogs often involves analyzing a fecal sample for the presence of the parasite using specialized tests.

What Is Giardia in Dogs?

Giardia, a microscopic parasite found in the intestines of dogs, has the ability to form cysts that are excreted in the dog’s stool. These cysts can persist in the environment and pose a risk of infection to any unsuspecting animal or human that inadvertently ingests them.

Among the various species of Giardia, Giardia intestinalis (also known as Giardia duodenalis or Giardia lamblia) is particularly significant as it infects mammals, including dogs and humans.

When Giardia infects the intestines, it interferes with the normal absorption of water and nutrients, resulting in digestive problems such as diarrhea, vomiting, and malabsorption. This can further lead to weight loss and impaired growth, particularly in young or vulnerable dogs.

To diagnose Giardia infection in dogs, veterinarians often examine stool samples for the presence of the parasite using specialized tests. Treatment typically involves specific medications prescribed by a veterinarian, accompanied by diligent hygiene practices to prevent reinfection and minimize the risk of transmission to other animals and humans.

To mitigate the impact of Giardia, providing clean drinking water, maintaining proper sanitation, and avoiding contact with potentially contaminated environments are crucial preventive measures. Regular veterinary check-ups and fecal examinations help in early detection and timely treatment of the infection, promoting the overall health and well-being of dogs.

Giardia in Dogs:

Symptoms of Giardia in Dogs

Giardia in dogs is a disease characterized by the presence of watery diarrhea as its primary symptom. Alongside diarrhea, dogs affected by Giardia may experience additional symptoms such as vomiting, excessive foul-smelling gas, reduced appetite, decreased energy levels, and frequent urges to defecate.

It is noteworthy that dogs, as well as other animals, can harbor Giardia in their intestines without showing any signs of illness, a condition known as subclinical infection. Since routine testing for Giardia is not typically conducted in healthy dogs, the prevalence of subclinical infections remains uncertain.

The potential existence of asymptomatic Giardia carriers among otherwise healthy dogs emphasizes the importance of maintaining proper hygiene practices in handling animal feces. This extends beyond the initial discomfort associated with fecal matter. Preventive measures such as regular handwashing, prompt removal and proper disposal of feces, and maintaining clean living environments for pets become vital to prevent the transmission and spread of Giardia.

What Causes Giardia In Dogs?

Cysts shed in the stool of infected dogs, cats, humans, and other animals pose a significant risk for transmission. These cysts have the ability to remain viable and infectious for several weeks, particularly in soil. Your dog can become infected with Giardia through various means, including:

  1. Ingesting water that has been contaminated with feces from an infected animal.
  2. Walking through or playing in an area contaminated with Giardia cysts and subsequently licking their paws or cleaning their body.
  3. Coming into contact with feces from an infected cat or dog.
  4. Being exposed to unsanitary conditions, such as a dirty animal crate or litter box, particularly during travel.

It is important to note that young dogs, especially puppies under six months of age, are at a higher risk of Giardia infection. Additionally, stray and shelter dogs have a greater likelihood of being infected compared to domestic pets.

To mitigate the risk of Giardia infection, it is crucial to practice good hygiene and sanitation measures. These include providing clean drinking water, maintaining a clean living environment for your pet, promptly cleaning up feces, and ensuring proper handwashing after handling animals or their waste. Regular veterinary check-ups and fecal examinations can also aid in early detection and appropriate treatment if necessary.

What Is the Treatment for Giardia in Dogs?

If your dog is experiencing diarrhea, it is important not to ignore the issue. Seeking veterinary attention is crucial, as your veterinarian will perform diagnostic tests to determine the underlying cause of the diarrhea.

Traditionally, Giardia diagnosis involved examining stool samples under a microscope. However, this method can be challenging and yield less accurate results compared to modern diagnostic tests like enzyme-linked immunosorbent assay (ELISA), immunofluorescent assay (IFA), and polymerase chain reaction (PCR).

If your dog is diagnosed with Giardia, your veterinarian will prescribe appropriate medication. The most common treatment involves a five-day course of metronidazole. Another drug commonly used is fenbendazole.

In addition to medication, your dog may require rehydration fluids and nutritional support to regain any lost weight or nutrients. It is also essential to bathe your pet with suitable shampoo to remove any fecal material present on their fur. Ingesting cysts from contaminated fur can lead to reinfection.

How Vets Diagnose Giardia in Dogs

When you take your dog to the veterinarian for diarrhea, they will perform a comprehensive evaluation to assess your dog’s general health and hydration levels. This will include gathering a complete medical history and conducting a physical examination to check for signs of intestinal discomfort, gas, and potential exposure to Giardia.

To investigate the possibility of Giardia infection, known as Giardiasis, your veterinarian is likely to recommend the following tests:

  1. Fecal Test: This test aims to identify routine intestinal parasites, and many veterinarians may also send a fecal sample to a laboratory for further analysis.

  2. Parvovirus Test: Since parvovirus is a severe and preventable viral infection that can cause diarrhea in dogs, your veterinarian may perform a test specifically designed to rule out this potential cause.

  3. “Snap Test” or Microscope Evaluation: Your veterinarian might employ a rapid in-house test called a “snap test” or examine a stool sample under a microscope to look for evidence of Giardia infection.

Based on the test results and clinical findings, your veterinarian will provide a proper diagnosis and recommend an appropriate treatment plan, which may include medications, fluid therapy, dietary adjustments, and hygiene practices. By working closely with your veterinarian, you can effectively address your dog’s condition and promote their recovery.

How Can You Prevent Giardia in Dogs?

Ensure that your dog always has an ample supply of clean water in their bowl. Encourage them to drink exclusively from their designated bowl whenever they are thirsty and discourage them from consuming water from other sources.

If the water supply in your area is known to potentially contain Giardia, consider using a filter that specifically removes the cysts. Another effective method to make the water safe for your dog is by boiling it, as this process will eliminate the Giardia cysts.

It is important to be aware that even seemingly healthy dogs can shed Giardia cysts in their feces. Therefore, it is crucial to promptly clean up their waste to ensure that your yard and the surrounding environment remain safe and free from this infection.

Recovery and Management of Giardia in Dogs

Dogs that have been infected with Giardia do not develop immunity against future infections. In fact, dogs that have recently cleared a Giardia infection can easily become reinfected. This emphasizes the importance of thorough disinfection of all living areas accessible to your dog. Utilizing ammonia, diluted bleach solutions, or steam cleaning can be effective in eliminating Giardia cysts from the environment. Additionally, it is crucial to promptly pick up your dog’s feces and properly dispose of it, whether it occurs during walks or in your yard.

Eliminating Giardia from the environment can be challenging due to the cysts’ resilience. Contaminated soil or indoor areas can remain infectious for months under the right conditions. Hence, rigorous cleaning practices and avoidance of these areas whenever possible are essential.

If you have other pets in your household, it is important to inform your veterinarian. Discuss with your vet whether administering medications to the other animals as a preventive measure is advisable, considering the highly contagious nature of Giardia.

Due to the contagiousness of Giardia, regular follow-up visits to the veterinarian for rechecks are necessary. Multiple negative tests are required to ensure the eradication of the parasite before you can relax and feel confident that the infection has been eliminated.

If your family includes a crawling baby or an immunocompromised individual, the vet may require additional negative Giardia tests to ensure complete eradication of the parasite and safeguard the health of vulnerable individuals.

To further manage and prevent Giardia infections, consider the following tips:

  • Prior to bringing a new pet home and introducing them to your existing animals, schedule a stool check and Giardia testing to prevent the introduction of the parasite.
  • Use a monthly heartworm preventative that also targets gastrointestinal parasites to keep your dog in optimal health.
  • Keep outdoor sandboxes covered when not in use to prevent contamination.
  • Maintain a regular checkup schedule with your veterinarian, and always opt for fecal parasite testing to detect and address any potential infections.
  • If possible, prevent your dog from hunting and consuming rodents and other small animals, as they can be potential sources of Giardia transmission.

By implementing thorough environmental management and following preventive measures, you can minimize the risk of Giardia infection in your dog and promote a safe and healthy living environment for your entire family, including vulnerable individuals. Regular communication and collaboration with your veterinarian are key in effectively managing and preventing the spread of this persistent parasite.

Does a Dog with Giardia Need a Special Diet?

A dog with Giardia may benefit from a special diet during the recovery process, but it’s important to consult with your veterinarian for specific dietary recommendations tailored to your dog’s needs. While there isn’t a universally prescribed diet for dogs with Giardia, certain dietary adjustments can help support their recovery and alleviate gastrointestinal symptoms.

Here are some general guidelines to consider:

  1. Easily Digestible Food: Opt for easily digestible food options that are gentle on the stomach. This can include commercial diets specifically formulated for gastrointestinal health or homemade bland diets, such as boiled chicken and rice. These diets are often easier for dogs with Giardia to tolerate and can help soothe the digestive system.

  2. Probiotics: Probiotics are beneficial bacteria that promote a healthy gut flora. They can help restore the balance of gut bacteria, which may be disrupted during a Giardia infection. Your veterinarian can recommend a suitable probiotic supplement or incorporate probiotics into the diet to aid in the recovery process.

  3. Fiber: Increasing dietary fiber can help regulate bowel movements and promote gastrointestinal health. Adding a small amount of plain canned pumpkin (not pumpkin pie filling) to your dog’s food can provide additional fiber and aid in firming up loose stools.

  4. Limited Treats: During the recovery period, it’s best to limit or avoid treats that may upset the digestive system further. Stick to the prescribed diet and gradually reintroduce regular treats once your dog has fully recovered.

Every dog is unique, and individual dietary needs may vary. Your veterinarian will consider your dog’s overall health, nutritional requirements, and specific condition when recommending a suitable diet. It’s important to follow their guidance closely to ensure your dog’s optimal recovery and well-being.

In addition to dietary adjustments, it’s crucial to maintain good hygiene practices, including proper sanitation, regular handwashing, and cleaning of food and water bowls, to minimize the risk of reinfection and promote a healthy environment for your dog.

Frequently Asked Question

What are the symptoms of Giardia in dogs?

Dogs infected with Giardia may experience symptoms such as diarrhea (which can be watery or greasy), vomiting, weight loss, decreased appetite, lethargy, excessive gas, and frequent urges to defecate.

How do dogs get infected with Giardia?

Dogs become infected with Giardia by ingesting the cysts, which are present in the feces of infected animals. They can acquire the infection by drinking contaminated water, coming into contact with contaminated environments, or through direct contact with infected animals.

Can dogs with Giardia infect humans?

Yes, Giardia can be transmitted between dogs and humans. It is a zoonotic disease, meaning it can be transmitted between animals and humans.

How is Giardia diagnosed in dogs?

Diagnosis is typically made by examining a fecal sample under a microscope to detect the presence of Giardia cysts. However, more advanced diagnostic tests, such as enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction (PCR), may also be used for accurate detection.

Can Giardia be treated in dogs?

Yes, Giardia in dogs can be treated with appropriate medications prescribed by a veterinarian. The most commonly used drugs are metronidazole and fenbendazole. The treatment duration may vary, but it typically lasts for several days.

Are there any side effects from Giardia medications?

Some dogs may experience mild side effects, such as gastrointestinal upset or loss of appetite, while undergoing Giardia treatment. It’s essential to closely follow the veterinarian’s instructions and report any concerns or adverse reactions.

How long does it take for a dog to recover from Giardia?

The recovery time can vary depending on the severity of the infection and the effectiveness of the treatment. In most cases, dogs show improvement within a few days to a couple of weeks after starting treatment.

How can I prevent Giardia in my dog?

To reduce the risk of Giardia infection, it’s important to practice good hygiene and sanitation. This includes providing clean drinking water, avoiding contact with contaminated environments, promptly cleaning up feces, and maintaining a clean living environment for your dog. Regular veterinary check-ups and fecal examinations can also help detect and treat any potential infections early.


Giardia is a microscopic parasite that can cause significant gastrointestinal distress in dogs. Common symptoms of Giardia infection include watery diarrhea, vomiting, foul-smelling gas, decreased appetite, decreased energy, and frequent urges to defecate. It is important to note that some dogs may be asymptomatic carriers, shedding the parasite without displaying obvious signs of illness.

Giardia is primarily transmitted through the ingestion of cysts found in contaminated water, soil, or feces. Dogs can easily become infected by drinking contaminated water, walking or playing in contaminated areas, or coming into contact with infected feces. Young dogs, especially puppies under six months of age, are more susceptible to infection.

Prompt veterinary attention is crucial if you suspect your dog has Giardia. A veterinarian will conduct diagnostic tests such as fecal examinations, enzyme-linked immunosorbent assays (ELISA), immunofluorescent assays (IFA), or polymerase chain reaction (PCR) to confirm the presence of Giardia and rule out other potential causes of gastrointestinal symptoms.



Paula patton is an avid dog lover and pet enthusiast with a wealth of knowledge in pet food and treatment. With her vast experience, she has gained valuable insights into the world of pets and their needs. Through her writings, Paula shares her expertise, helping fellow pet owners make informed decisions for their furry companions. Her passion for animals shines through every word, making her a trusted source for all things related to pets.

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