Giardia in Dogs – Get Expert Insights on Symptoms, Diagnosis, Treatment

Giardia in Dogs – Get Expert Insights on Symptoms, Diagnosis, Treatment

Giardia is a small single-celled organism that lives in the gut of humans and most domestic animals. There are different subtypes of giardia and some are host specific, ie. infects only 1 animal species, while other subtypes of Giardia can infect several different animal species. Some of the Giardia types can infect both humans and animals, e.g. dogs and cats, thus forming what you call a zoonosis.

What are the symptoms of giardia?

In dogs infected with Giardia, mild to severe diarrhea is seen, worst in young puppies. The stools are typically smelly and light in color that may appear fresh blood.

You can see weight loss, but rarely decreased appetite. Giardia infections do not in themselves cause fever and vomiting.

From a dog infected until clinical symptoms are seen, it takes between 5 and 12 days, the average is approx. 8 days. Not all infected dogs get symptoms, they are called asymptomatic carriers, and they can pass the infection on to other dogs without even being sick.


How can your vet diagnose giardia?

The diagnosis is made by examining the stool for Giardia cysts. This can be done with a simple test at the vet or the sample can be submitted to a laboratory.

How is giardia treated?

Giardia infections can be treated medically, but at the same time require thorough cleaning and disinfection in the environment to avoid reinfections.

Medical treatment

There are no drugs registered for the treatment of Giardia in animals, nor are any drugs proven to be 100% effective.

Most often Fenbendazole is used once daily for 5 days and the cure is repeated after 14 days.
Metronidazole may also be used, but has been shown to be less effective than Fenbendazole in the treatment of Giardia in dogs, and metronidazole may cause some side effects in the form of decreased appetite, vomiting and altered behavior.


Prevention of reinfection

As Giardia can survive in the environment for up to several months, it is important to focus on eradicating Giardia in the environment around the infected dogs so that reinfection is avoided. This is especially important in dog kennels where the infection pressure is high.

The process should proceed as follows

  • All animals are put on medical treatment and moved to a Giardia-free area on the 5th day of 1st Fenbendazole treatment.
  • The infected area and fixtures are thoroughly cleaned, preferably with steam, and thoroughly disinfected with a chemical disinfectant, e.g. Viakon S. Then area and furniture should be allowed to dry completely, preferably for several days.
  • Before putting the dogs back, they must be washed to ensure that they do not carry Giardiacysts in the coat. The animals can be washed in a regular dog shampoo.
  • The Giardi cysts can also be transmitted by humans and therefore a foot bath for disinfecting footwear should be established before accessing the cleaned area.

What is the future of your dog if it has giardia?
The prognosis for the dog with the right treatment is good, but it requires that the risk of reinfection in the environment is removed. Since there are no drugs that have been found to be 100% effective, there is a risk that the treatment will only beat the infection and that the dog may have symptoms again if the immune system falls for another reason.

Why do dogs get giardia?

Giardia cysts are excreted in the stool and transmitted by an animal or human being consuming Giardia cysts in e.g. faecal contaminated water or a contaminated environment. Giardia can survive in the environment for months, especially in humid and cool conditions.

What is the risk of your dog getting giardia?
In dogs in Denmark, Giardia infections with clinical symptoms are relatively rare, and most often only in kennels and other places where there are many dogs gathered in a little space, as well as in very young puppies and dogs with reduced immune system.

Why are Giardia so difficult to get rid of?

dog sleeping

There are actually good medications for Giardia that kill the parasites. Nevertheless, many pet owners are unpleasantly surprised because a few days after treatment, giardia can be detected in the feces of their four-legged friend again. How can that be?

Often, freshly treated dogs and cats immediately become infected with giardia in their immediate vicinity. The parasite’s very resistant cysts sit, for example, in the fur of the anal region, in the blankets and pillows or on the bowl and toys. In the long term, your household will only become free of guards again if you manage to eliminate these guard cysts.

Can giardia infect humans?
Giardia is a potential zoonosis, ie. that certain of the giardia subtypes can infect dogs and humans, however, not all of them. Unfortunately, we cannot distinguish between the different subtypes and therefore one should be aware that there is a potential risk of human infection. Therefore, you should maintain an extra good hygiene when handling infected animals and areas, and contact your doctor if you have an animal with giardia and even get diarrhea symptoms.


dog and vegetABLE TOY

No medication is 100% effective and so is the cure for Giardia. It is therefore important to provide the gut system and the animal’s own immune system with the best conditions to help fight the parasite.
We recommend giving so-called probiotics and lactic acid bacteria. It’s called either ZooLac or Canikur. It is also important to provide extra fiber in the diet. Optionally mixed with sparing food.
Dogs (and less frequently cats) who have a “delicate stomach” and who have previously had thin stomachs and extra intestinal gas when given certain treats and chewing bones may benefit from getting the same diet as the multi allergy. In that case, they should have Hills Z / D (or equivalent) for 3-4 weeks without getting treats or leftover other “candy” next door.


dog grooming

The parasite can be infected from carpets, bowls and baskets – even after several months. It can still infect after the treatment is done and in this way a dog or cat can infect itself again after you have finished giving medication.
Thorough cleaning of all your pet’s stuff is crucial to whether we can get the parasite eradicated.
Since some types of Giardia can infect us humans, you should avoid using the same brushes and rags that you otherwise use and do not put bowls in the dishwasher.
We recommend using Viacon S, Rodalon or Chlorine for cleaning. Boiling water can also be effective for bowls and brushes. Liquor is not sufficiently effective against the parasite.
It is also a good idea to wash the dog or cat, as there may be parasites in the coat. You can, for example. do in connection with each treatment.
Wear gloves and wash your hands thoroughly also under the nails.

The most important hygiene measures against Giardia at a glance

cleaning sign

Useful measures to prevent transmission to other animals and to prevent reinfection are:

  • Collect feces and remove the feces in a closed plastic bag with household waste.
  • Thorough cleaning of all surfaces contaminated by faeces (floors and walls) with subsequent complete drying, the use of steam jets (> 60 ° C) is optimal.
  • Disinfect all surfaces or objects with suitable disinfectants.
  • Clean the feed and drinking vessels with boiling water daily or in the dishwasher at> 65 ° C.
  • Clean the litter box with boiling water daily and then dry thoroughly.
  • Wash blankets and pillows hot (> 65 ° C). Non-washable but possibly contaminated textiles with household waste.
  • Vacuum and clean the scratching posts thoroughly.
  • If necessary, dogs should also bathe cats thoroughly and shampoo them (e.g. with products containing chlorhexidine digluconate *) in order to clean them of adhering residues, if necessary shear long hair in the anal area.
  • Pay attention to hygiene, especially for immunocompromised people and small children . Wash hands after handling dog and cat.


Some animals will continue to have Giardia in the intestinal system even though they have become healthy. So they have normal stools and are healthy, but if they get a thin stomach from another disease (eg menopause or colds) they can flare up again.
If the symptoms are mild we do not necessarily do anything extra, but sometimes it may be necessary to test for Giardia again even after many years.

Is there anything else I can do to prevent my pet from having giardia problems again?

woamn and dog

We are often asked this question, but it is difficult to answer. What is certain is that giardia often causes no problems such as diarrhea in healthy animals. This is precisely why giardia are so widespread in the environment: Many four-legged friends with giardia on board run through the area without anyone knowing because they are not sick.

Unfortunately, to our knowledge, there is no scientific investigation that could “measure” whether strengthening the immune system and measures to promote intestinal health cause an animal to get rid of or tolerate the pathogen itself in the future. However, we often recommend our patient owners to take special care of their animal’s gut health, especially after antibiotic treatment. It is well known that a stable healthy intestinal flora (microbiome) makes it more difficult for pathogens to nest in the intestine.

For example, it makes sense to give a probiotic after antibiotic treatment. Also prebiotics (which the beneficial intestinal bacteria food supply) are recommended, preferably in combination with a probiotic. In our own experience, feeding colostrum can also help promote intestinal health and resistance. It also has probiotic properties and helps to strengthen the intestinal barrier.

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Mehul D

I love pets especially dogs and cats. I have created this website to spread useful information about pets and to help people to take care of their pets in a better way.