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Giardia is one of the most common parasites in dogs. Dogs can become infected in many ways but rarely become seriously ill.

Giardia in dogs – frequently found lodgers

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Giardia (Giardia duodenalis, also Giardia intestinalis, Giardia lamblia) are unicellular parasites that live in the dog’s intestines and also multiply there. They are among the most common parasites in the world, affecting dogs (and cats, rabbits, chinchillas…) of all ages. However, puppies or young dogs under the age of one year or animals that are already weak, e.g. B. those with chronic diseases.

An infection with Giardia in dogs is called giardiasis and is a possible trigger for intestinal inflammation. Giardiasis is a zoonosis, i.e. a disease that can theoretically also spread to humans.

The development cycle of Giardia in dogs

Dogs ingest the permanent form of Giardia, so-called cysts, through contaminated water or food. In the intestine, the reproductive forms, so-called trophozoites, develop from this. These attach themselves to the intestinal mucosa or “swim” freely in the intestine; there they also multiply. They feed on intestinal contents and small parts of the intestinal mucosa, preferring easily digestible carbohydrates and sugars.

In the rear part of the large intestine, the trophozoites become cysts, which are well protected against external influences such as dryness by their shell. Excreted with the faeces, they can survive in the outside world for a relatively long time. In the feces they are contagious for about a week, in a humid environment for up to 3 months.

A dog with Giardia excretes up to 10 million cysts per gram of feces over a period of 4-5 weeks. Just a few of these giardia cysts are enough to infect the next animal.

Increased risk of infection in groups

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Dogs that are kept in groups or that frequently meet many other dogs have an increased risk of infection. Due to the large number of dogs, the Giardia always quickly find a host again, one speaks of a high “infection pressure”.

This concerns:

  • animal boarding houses
  • shelters
  • dog schools
  • dog breeds
  • Working dogs in kennels (sled dogs, hunting packs, etc.)

Unfavorable housing conditions with boxes and kennels that are too small and poorly cleaned or poor hygiene management promote both the infection rates and visible diseases caused by Giardia in dogs, because stressed animals become seriously ill more quickly.

Where does my dog ​​get Giardia?

Because Giardia is so common, your dog can get it from almost anywhere. They can be found in polluted water (puddles, lakes) or on polluted soil, as well as in contact with other dogs, because Giardia is also transmitted by dogs licking it if it sticks to their fur. Accordingly, your dog can also become infected in your own garden.

Dogs infected with Giardia that have no symptoms repeatedly excrete pathogens without the knowledge of the owner and can thus serve as a source of infection. If the Giardia stick to the fur or around the anus, the dog can also become infected again and again.

Another transmission route for Giardia in dogs is flies, which, after contact with infected feces, stop on the dog’s food and leave behind Giardia cysts.

By the way: Giardia in puppies often comes from the mother, e.g. in personal hygiene.


Most dogs that contract Giardia do not develop it. A healthy organism copes well with a certain number of protozoa and eliminates them itself.

But when Giardia strikes dogs that are already weak, the disease can be more severe. Whether this happens depends on various factors:

Age: Puppies or young dogs up to 1 year old are affected more frequently.
Stress: Both psychological and physical stress (e.g. hard training) increase the risk of visible disease.
Intestinal flora: If the normal bacterial composition in the intestine is disturbed, this offers more surface for the pathogens to attack. This can e.g. B. be diet-related, but can also be triggered by other infections (e.g. other parasites) or by stress.
Type of Giardia: There are different strains of Giardia in dogs and some seem to be more aggressive than others.
If symptoms do occur, they can be very variable: Dogs with Giardia sometimes show diarrhea, which usually ends on its own after 24 hours. However, it can also persist for months, especially in young animals. The inflammation of the small intestine leads to indigestion, poorer absorption of food components and recurring diarrhea with runny faeces, which sometimes smells rancid to sweet and contains fat and mucus. Blood admixtures are rare. Young dogs continue to lose weight, even if they continue to eat well.

However, it can also be the case that Giardia causes stomach pains in the dog, with a tense abdominal wall and a hunched back. Bloating, vomiting, fever, all of these can occur as a result of giardiasis.

If the disease persists, poor feed conversion can even lead to skin reactions such as a dull coat and dandruff.

The infection with Giardia in dogs therefore lasts for different lengths of time and can also cause different degrees of disease symptoms.

Diagnosis of Giardia in dogs

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If you notice these or other symptoms in your dog, please consult a veterinarian! Giardiasis can be very unpleasant for animals with a weaker immune system, such as puppies, senior citizens or chronically ill dogs.

The vet will examine your pet thoroughly to find the cause of the symptoms of the disease. (Besides the dog’s Giardia, there can be other causes for this clinical picture.) A fecal examination usually provides information: There are now good rapid tests that indicate the presence of Giardia.

How to treat giardia in dogs

A dog that tests positive for Giardia but shows no signs of the disease does not need treatment. His immune system copes well with the pathogen and keeps it in check. Also, once treated, there is a very good chance that it will quickly become infected again somewhere – an endless cycle.

There are drugs against Giardia in dogs that work well and make sense for more severely affected animals.

If there are other animals in the household, your veterinarian will discuss with you whether these also need treatment. Unfortunately, the problem is that the disease often recurs quickly, particularly in group housing. Then a renewed Giardia treatment of the dogs is necessary.

What else helps against Giardia in dogs?

If your dog has giardia, is bothered by it and is being treated for it, you can increase the potential for treatment success by cleaning the home thoroughly. Dog blankets, toys, etc. should be washed as hot as possible (at least 60°C), as should sofas, beds, etc. used by the dogs. If covers cannot be washed, use a steam cleaner (also applies to the car).

Feeding bowls should be cleaned daily – even without Giardia!

Bathing your dog with dog shampoo can also help to remove adherent Giardia from the coat. Please talk to your vet about it!

Pre- or probiotics support the intestinal flora. A diet with as few carbohydrates and a lot of crude fiber as possible has a supporting effect against Giardia in dogs.

How do I protect myself?

It is relatively rare for people to contract Giardia from their dog. This is because there are different strains of Giardia that do not affect all animal species and humans equally. However, it is possible, which is why people with a weakened immune system and small children should follow basic hygiene rules: Regular hand washing, especially after contact with the dog, is essential. Disposing of feces hygienically in closed plastic bags and not kissing the dog should also be a matter of course.

Can I prevent Giardia in my dog?

Unfortunately, Giardia is so widespread in dogs that you can hardly prevent your pet from becoming infected. But you can support it with a good, balanced diet that promotes healthy intestinal flora. Optimal husbandry conditions with plenty of exercise in the fresh air also keep him healthy. If he does become infected, he will then be able to deal better with the uninvited guests. On the other hand, you should watch puppies and other susceptible animals closely and, if necessary, go to the vet as soon as possible to prevent bad conditions at an early stage.

Giardia in dogs: conclusion

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Fortunately, the stubborn little parasites are usually not dangerous. However, since they can become uncomfortable for weakened animals and humans, you should definitely go to the vet if you suspect Giardia in your dog.