Giardia in dogs and cats

What is Giardia?

Giardia is a genus of small small intestinal parasites that occur in various animal species and can also be dangerous to humans as a zoonotic pathogen. A widespread exponent of Giardia is Giardia intestinalis, also called Giardia lamblia or duodenalis, which occurs in mammals and birds. The infection usually occurs through so-called dirt and smear infections, i.e. direct contact with other animals or their feces without an intermediate host. The infectious cysts (eggs) are ingested orally. The dose that an animal must ingest to become infected is just a few cysts. Once they have reached the small intestine, they attach themselves to the intestinal wall and destroy the intestinal mucosal cells and, by dividing into two, form resistant cysts that are excreted in the feces. This occurs 4-16 days after infection.

Particularly resistant

Giardia, in its permanent form as so-called Giardia cysts, has a particularly resistant protective shell. They survive in animal feces for up to a week. During this time the feces are highly contagious. The Giardia infection therefore spreads particularly quickly in places where there are many animals. But the parasite can also survive in its permanent form in water or soil for several weeks. The parasite even survives for several months in cool, moist environments. For this reason, cats that are kept exclusively indoors can become infected particularly easily either by carrying the pathogen in the pet owner's clothing and shoes or by soiling the balcony, for example from birds. Infections can also occur, for example, by drinking water contaminated with feces or by licking your paws.

How do I know if my animal has Giardia?

While an infection is not always visible in healthy animals and is usually asymptomatic, noticeable symptoms often occur earlier, especially in sick and/or older animals with weakened immune systems or puppies with not yet fully developed microflora in the intestine. These are related to the attachment of trophozoites to the intestinal wall. Attachment leads to inflamed and damaged intestinal lining, nutrient deficiencies and fluid loss. The consequences are watery diarrhea, usually mixed with mucus or even blood, which can occur acutely but also chronically, as well as dehydration and severe weight loss despite normal food intake. Vomiting, weakness and fever can complement these symptoms.

Speed is required

If there are appropriate symptoms and suspicion, the correct treatment should be initiated by the vet as quickly as possible. Giardia rapid tests are a diagnostic aid for the early detection of Giardia infections. This immunochromatographic test is usually carried out by the veterinarian in the practice, but can also be carried out at home. It reliably detects the lowest pathogen concentrations in the feces and delivers a clear and quick result.

Avoid reinfection

If an animal has been proven to be infected with Giardia, it is not always easy to permanently end the infection cycle. Treatment at the vet alone is often not enough. Due to the high and highly infectious cyst load in the excreted feces and the long survival time of the cysts in the environment, the risk of reinfection and infection of other animals in the same household or outside is particularly high.

In addition to administering parasite-killing medications, hygiene measures are particularly helpful in keeping the environment free of Giardia and preventing reinfection. These should be carried out throughout the entire treatment phase and afterwards. This is the only way to prevent the animal or other animals from becoming infected again and again.

To combat Giardia in the environment, surface disinfectants are available for all areas of life. They are part of the hygiene measures to be carried out and help to disinfect items, floors and surfaces that are difficult to wash and to neutralize odors. They should be used for acute infections, but can also be used preventatively. In addition to spraying objects or textiles that are difficult to wash, washing textiles at at least 65°C is one of the first measures that should be carried out if an infection is detected.

Since animals can pick up the pathogen particularly quickly from the environment with their paws, or since it settles in the fur of the anal region when they have diarrhea, it is advisable to also treat the animal externally. Shampoos with the active ingredient chlorhexidine digluconate1 have a strong cleansing effect. The active ingredient also destroys the cell wall of organisms. The skin and fur are disinfected and freed from bacteria. Dirty areas in the anal region should be cleaned immediately and, if necessary, daily with appropriate shampoos. Trimming the fur in the anal area also makes sense in long-haired breeds during a Giardia infection.

Structure after infection

Giardiosis puts a lot of strain on the animal's gastrointestinal tract in particular. Damage to the intestinal wall usually results in a reduced absorption of micronutrients, a weakened immune system and impaired digestion. The medications used by veterinarians to combat giardia, such as fenbendazole or metronidazole, also put a strain on the microbiome. Therefore, build up the animal's intestinal flora immediately after the infection has been overcome. Synbiotic preparations, a mix of probiotics and prebiotics, which stabilize digestion and sustainably strengthen the intestinal flora, are particularly suitable here.